I Synchronizing shared objects

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shared_memory_object shm用法 -回复

shared_memory_object shm用法-回复Shared_memory_object (shm)是一种用于在进程之间共享内存数据的机制。

它通过在不同进程之间创建共享的存储区域，实现了高效的数据交换和通信。

在本文中，我们将详细介绍shm的用法，并逐步回答关于它的一些常见问题。

首先，我们来了解shm的基本概念和原理。

shm可以被看作是一种特殊的文件对象，它存在于文件系统中，并且可以被不同的进程通过引用来访问和操作。

与普通文件不同的是，shm不会被实际地存储在磁盘上，而是存储在计算机的主内存中。

这样设计的目的是为了提供更快速、低延迟的数据传输。

在使用shm之前，我们需要调用相关的系统函数来创建和管理shm对象。

首先，我们需要使用shm_open()函数来创建一个共享内存对象，并指定一个唯一的名称作为标识符。

当一个进程调用shm_open()函数时，系统会将返回一个文件描述符，用于后续的操作。

接下来，我们可以使用ftruncate()函数来指定shm对象的大小，即为这个共享内存对象分配一块特定的内存区域。

这样，其他进程就可以通过该对象的标识符来访问这块内存区域，并向其中写入或读取数据。

一旦shm对象被创建和初始化，我们就可以使用mmap()函数将shm对象映射到当前进程的地址空间中。

这样，我们就可以直接通过指针来访问和操作共享内存区域的数据。

与传统的进程间通信方式相比，这种直接的内存映射方式具有极高的效率和灵活性。

当需要对共享内存区域进行读写操作时，我们只需要简单地访问内存映射的指针即可。

任何对该指针的操作都会直接影响到共享内存区域中的数据。

这种数据的实时共享和更新，使得不同进程之间可以实时地交换信息和进行协作。

在使用完shm对象后，我们需要调用相应的系统函数来释放和销毁这个对象。

首先，我们需要使用munmap()函数解除内存映射，将shm对象从进程的地址空间中移除。

接着，我们可以使用shm_unlink()函数彻底删除shm对象，释放相关的系统资源。

SAPPISLD基础及配置9256

5© 2012 SAP AG. All rights reserved.
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The Basic Idea of SLD
Graphical Design Tool
Applications and Tools
Technical Configuration
Validation Registration
Software Logistics
4© 2012 SAP AG. All rights reserved.
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The Three Dimensions
System Landscapes have three dimensions: • Solution Dimension – what software processes are
installed • Transport Dimension – DEV, QA , PROD • Technical Dimension – what products are installed on
8© 2012 SAP AG. All rights reserved.
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Catalogs
The two main areas of SLD are: the software catalog and the landscape description.
The Software Catalog describes the installed products and their constituent components. The software catalog is delivered with content about all SAP products. Customers and Partners can extend this catalog with information about software from other vendors. It describes the component information, possible combinations and dependencies.

英文技术面试

Question: What is transient variable(局部变量)?Answer: Transient variable can't be serialize. For example if a variable is declared as transient in a Serializable class and the class is written to an ObjectStream, the value of the variable can't be written to the stream instead when the class is retrieved from the ObjectStream the value of the variable becomes null.Question: Name the containers which uses Border Layout as their default layout?Answer: Containers which uses Border Layout as their default are: window, Frame and Dialog classes.Question: What do you understand by Synchronization?Answer: Synchronization is a process of controlling the access of shared resources by the multiple threads in such a manner that only one thread can access one resource at a time. In non synchronized multithreaded application, it is possible for one thread to modify a shared object while another thread is in the process of using or updating the object's value. Synchronization prevents such type of data corruption.E.g. Synchronizing a function:public synchronized void Method1 () {// Appropriate method-related code.}E.g. Synchronizing a block of code inside a function:public myFunction (){synchronized (this) {// Synchronized code here.}}Question: What is Collection API?Answer: The Collection API is a set of classes and interfaces that support operation on collections of objects. These classes and interfaces are more flexible, more powerful, and more regular than the vectors, arrays, and hashtables if effectively replaces.Example of classes: HashSet, HashMap, ArrayList, LinkedList, TreeSet and TreeMap.Example of interfaces: Collection, Set, List and Map.Question: Is Iterator a Class or Interface? What is its use?Answer: Iterator is an interface which is used to step through the elements of a Collection.Question: What is similarities/difference between an Abstract class and Interface?Answer: Differences are as follows:Interfaces provide a form of multiple inheritance. A class can extend only one other c lass. Interfaces are limited to public methods and constants with no implementation. Abstract classes can have a partial implementation, protected parts, static methods, etc.A Class may implement several interfaces. But in case of abstract class, a class may extend only one abstract class.Interfaces are slow as it requires extra indirection to to find corresponding method in in the actual class. Abstract classes are fast.Similarities:Neither Abstract classes or Interface can be instantiated.Question: How to define an Abstract class?Answer: A class containing abstract method is called Abstract class. An Abstract class can't be instantiated.Example of Abstract class:abstract class testAbstractClass {protected String myString;public String getMyString() {return myString;}public abstract string anyAbstractFunction();}Question: How to define an Interface?Answer: In Java Interface defines the methods but does not implement them. Interface can include constants. A class that implements the interfaces is bound to implement all the methods defined in Interface.Emaple of Interface:public interface sampleInterface {public void functionOne();public long CONSTANT_ONE = 1000;}Question: Explain the user defined Exceptions?Answer: User defined Exceptions are the separate Exception classes defined by the user for specific purposed. An user defined can created by simply sub-classing it to the Exception class. This allows custom exceptions to be generated (using throw) and caught in the same way as normal exceptions.Example:class myCustomException extends Exception {// The class simply has to exist to be an exception}Question: Explain the new Features of JDBC 2.0 Core API?Answer: The JDBC 2.0 API includes the complete JDBC API, which includes both core and Optional Package API, and provides inductrial-strength database computing capabilities.New Features in JDBC 2.0 Core API:Scrollable result sets- using new methods in the ResultSet interface allows programmatically move the to particular row or to a position relative to its current positionJDBC 2.0 Core API provides the Batch Updates functionality to the java applications.Java applications can now use the ResultSet.updateXXX methods.New data types - interfaces mapping the SQL3 data typesCustom mapping of user-defined types (UTDs)Miscellaneous features, including performance hints, the use of character streams, full precision for java.math.BigDecimal values, additional security, and support for time zones in date, time, and timestamp values.Question: Explain garbage collection?Answer: Garbage collection is one of the most important feature of Java. Garbage collection is also called automatic memory management as JVM automatically removes the unused variables/objects (value is null) from the memory. User program cann't directly free the object from memory, instead it is the job of the garbage collector to automatically free the objects that are no longer referenced by a program. Every class inherits finalize() method from ng.Object, the finalize() method is called by garbage collector when it determines no more references to the object exists. In Java, it is good idea to explicitly assign null into a variable when no more in use. I Java on calling System.gc() and Runtime.gc(), JVM tries to recycle the unused objects, but there is no guarantee when all the objects will garbage collected.Question: How you can force the garbage collection?Answer: Garbage collection automatic process and can't be forced.Question: What is OOPS?Answer: OOP is the common abbreviation for Object-Oriented Programming.Question: Describe the principles of OOPS.Answer: There are three main principals of oops which are called Polymorphism, Inheritance and Encapsulation.Question: Explain the Encapsulation principle.Answer: Encapsulation is a process of binding or wrapping the data and the codes that operates on the data into a single entity. This keeps the data safe from outside interface and misuse. One way to think about encapsulation is as a protective wrapper that prevents code and data from being arbitrarily accessed by other code defined outside the wrapper.Question: Explain the Inheritance principle.Answer: Inheritance is the process by which one object acquires the properties of another object.Question: Explain the Polymorphism principle.Answer: The meaning of Polymorphism is something like one name many forms. Polymorphism enables one entity to be used as as general category for different types of actions. The specific action is determined by the exact nature of the situation. The concept of polymorphism can be explained as "one interface, multiple methods".Question: Explain the different forms of Polymorphism.Answer: From a practical programming viewpoint, polymorphism exists in three distinct forms inJava:Method overloadingMethod overriding through inheritanceMethod overriding through the Java interfaceQuestion: What are Access Specifiers available in Java?Answer: Access specifiers are keywords that determines the type of access to the member of a class. These are:PublicProtectedPrivateDefaultsQuestion: Describe the wrapper classes in Java.Answer: Wrapper class is wrapper around a primitive data type. An instance of a wrapper class contains, or wraps, a primitive value of the corresponding type.Following table lists the primitive types and the corresponding wrapper classes:Primitive Wrapperboolean ng.Booleanbyte ng.Bytechar ng.Characterdouble ng.Doublefloat ng.Floatint ng.Integerlong ng.Longshort ng.Shortvoid ng.V oidQuestion: Read the following program:public class test {public static void main(String [] args) {int x = 3;int y = 1;if (x = y)System.out.println("Not equal");elseSystem.out.println("Equal");}}What is the result?A. The output is equal?br>B. The output in not Equal?br>C. An error at " if (x = y)" causes compilation to fall.D. The program executes but no output is show on console.Answer: CQuestion: what is the class variables ?Answer: When we create a number of objects of the same class, then each object will share a common copy of variables. That means that there is only one copy per class, no matter how many objects are created from it. Class variables or static variables are declared with the static keyword in a class, but mind it that it should be declared outside outside a class. These variables are stored in static memory. Class variables are mostly used for constants, variable that never change its initial value. Static variables are always called by the class name. This variable is created when the program starts i.e. it is created before the instance is created of class by using new operator and gets destroyed when the programs stops. The scope of the class variable is same a instance variable. The class variable can be defined anywhere at class level with the keyword static. It initial value is same as instance variable. When the class variable is defined as int then it's initial value is by default zero, when declared boolean its default value is false and null for object references. Class variables are associated with the class, rather than with any object.Question: What is the difference between the instanceof and getclass, these two are same or not ? Answer: instanceof is a operator, not a function while getClass is a method of ng.Object class. Consider a condition where we useif(o.getClass().getName().equals("ng.Math")){ }This method only checks if the classname we have passed is equal to ng.Math. The class ng.Math is loaded by the bootstrap ClassLoader. This class is an abstract class.This class loader is responsible for loading classes. Every Class object contains a reference to the ClassLoader that defines. getClass() method returns the runtime class of an object. It fetches the java instance of the given fully qualified type name. The code we have written is not necessary, because we should not compare getClass.getName(). The reason behind it is that if the two different class loaders load the same class but for the JVM, it will consider both classes as different classes so, we can't compare their names. It can only gives the implementing class but can't compare a interface, but instanceof operator can.The instanceof operator compares an object to a specified type. We can use it to test if an object is an instance of a class, an instance of a subclass, or an instance of a class that implements a particular interface. We should try to use instanceof operator in place of getClass() method. Remember instanceof opeator and getClass are not same. Try this example, it will help you to better understand the difference between the two.Interface one{}Class Two implements one {}Class Three implements one {}public class Test {public static void main(String args[]) {one test1 = new Two();one test2 = new Three();System.out.println(test1 instanceof one); //trueSystem.out.println(test2 instanceof one); //trueSystem.out.println(Test.getClass().equals(test2.getClass())); //false}}转载请注明文章来源：笔试网—专业的笔试、面试资料搜索网站,<br>原文网址:/shiti.aspx?id=536086。

Shared-nothing

The Case for Shared NothingMichael StonebrakerUniversity of CaliforniaBerkeley, Ca.ABSTRACTThere are three dominent themes in building high transaction rate multiprocessor systems, namely shared memory (e.g. Synapse, IBM/AP conﬁgurations), shared disk (e.g. V AX/cluster,any multi-ported disk system), and shared nothing (e.g. Tandem, Tolerant). This paper argues that shared nothing is the pre-ferred approach.1. INTRODUCTIONThe three most commonly mentioned architectures for multiprocessor high transaction rate systems are:shared memory (SM), i.e. multiple processors shared a common central memoryshared disk (SD), i.e. multiple processors each with private memory share acommon collection of disksshared nothing (SN), i.e. neither memory nor peripheral storage is shared among processors There are several commerical examples of each architecture.In this paper we argue that SN is the most cost effective alternative.In Section 2 we present a "back of the envelope" comparison of the alternatives. Then in Sections 3 through 5 we discuss in more detail some of the points of comparison.2. A SIMPLE ANALYSISIn Table 1 we compare each of the architectures on a collection of 12 points.Each architecture is rated 1, 2 or 3 to indicate whether it is the best, 2nd best or 3rd best on each point.For certain points of comparison, there are apparent ties.In such situations we give each system the lower rating.Most of the ratings are self-evident, and we discuss only a few of our values.The ﬁrst two rows indicate the difﬁculty of transaction management in each environment. SM requires few modiﬁcations to current algorithms and is the easiest environment to support.Hence it receives a"1" for crash recovery.The "2" for concurrency control results from the necessity of dealing with the lock table as a hot spot.SN is more difﬁcult because it requires a distributed deadlock detector and a multi-phase commit protocol. SD presents the most complex transaction management problems because of the necessity of coordinating multiple copies of the same lock table and synchronizing writes to a com-mon log or logs.The third and fourth points are closely related.Data base design is difﬁcult in current one-machine environments, and becomes much harder in an SN system where the location of all objects must be speci-ﬁed. The other environments do not add extra complexity to the one-machine situation.Balancing the load This research was sponsored by the U. .S. Air Force Ofﬁce of Scientiﬁc Research Grant 83-0254 and the Naval Electronics Sys-tems Command Contract N39-82-C-0235System Feature shared nothing shared memory shared disk difﬁculty ofconcurrency223 controldifﬁculty ofcrash 213 recoverydifﬁculty ofdata base322 designdifﬁculty of312 load balancingdifﬁculty of132 high availabilitynumber of312 messagesbandwidth 132 requiredability toscale to large 132 number of machinesability to havelarge distances132 between machinessusceptibility to132 critical sectionsnumber of313 system imagessusceptibility to333hot spotsA Comparison of the ArchitecturesTable 1of an SN system is complex, since processes and/or data must be physically moved. It is obviously much easier in the other environments. The next ﬁve points are fairly straightforward, and we skip forward to critical sections.They hav e been shown to be a thorny problem in one-machine systems [BLAS79], and an SN system does not make the problem any worse. On the other hand, an SM system will be considerably more susceptible to this problem, while an SD system will be in-between.SN and SD systems have one system image per CPU, and system administration will be more complex than an SM system which has only a single system stly,all architectures are susceptible to hot spots.Several conclusions are evident from Table 1.First an SM system does not scale to a large number of processors. In my opinion this is a fundamental ﬂaw that makes it less interesting than the other architec-tures. Second,an SD system excells at nothing, i.e. there are no "1"s in its stly,one should note the obvious marketplace interest in distributed data base systems.Under the assumption that every vendor will have to implement one, there is little or no extra code required for an SN system.In order to justify implementing something else (e.g. SD) and paying the extra software complexity,one should be sure that SN has some insurrountable ﬂaws. In the next section we discuss the issues of data base design, load bal-ancing and number of messages, which are points of comparison where SN was the poorest choice.In each case we argue that the problems are unlikely to be very signiﬁcant.Then we discuss hot spots in Section 4, and argue that these are easier to get rid of than to support stly,we discuss concurrency con-trol, and suggest that scaling to larger data bases is unlikely to change the ratings in Table 1.Hence, we will conclude that SN offers the most viable and cost effective architecture.3. Problems with Shared NothingIt appears that most data base users ﬁnd data base design to require substantial wizardry.Moreover, tuning a data base is a subject that data base vendors have clearly demonstrated proﬁciency relative even to the wisest of their customers.To ordinary mortals tuning is a "black art".Consequently,I expect many automatic tuning aids will be constructed for most data managers, if for no other reason than to lower the technical support burden. There is no evidence that I am aware of that such tuning aids will be unsuccessful.Similarly,there is no evidence that automatic data base design aids will fail in an SN environment where the data base is partitioned over a collection of systems.Furthermore, balancing the load of an SN data base by repartitioning is a natural extension of such a design aid.More-over, applications which have a stable or slowly varying access pattern will respond successfully to such treatment and will be termed tunable.Only data bases with periodic or unpredictable access patterns will be untunable, and I expect such data bases to be relatively uncommon.Hence, load balancing and data base design should not be serious problems in typical environments.Consider the number of messages which an SN system must incur in a typical high transaction pro-cessing environment. The example consists of a data base with N objects subject to a load consisting entirely of transactions containing exactly k commands, each affecting only one record.(For TP1 the value of k is 4).For any partitioning of the data base, these k commands remain single-site commands.Suppose that there exists a partitioning of the data base into non-overlapping collections of objects such that all transactions are locally sufﬁcient [WONG83]. Such a data base problem will be termed delightful.Most data base applications are nearly delightful.For example, the TP1 in [ANON84] has 85% delightful trans-actions.Assume further that the cost of processing a single record command is X and the cost of sending and receiving a round-trip message is Y.For convenience, measure both in host CPU instructions, and call T = X/Y the technology ratio of a given environment. Measured values of T for high speed networks and rela-tional data bases have varied between 1 and 10 and reﬂect the relative efﬁciency of data base and network-ing software in the various situations.An environment where each is tuned well should result in a T of about 3.We expect the long term value of T to stay considerably greater than 1, because it appears much easier to ofﬂoad network code than data base code.As long as T >> 1, network costs will not be the dominent system cost in delightful data bases; rather it will be processing time on the local systems.Moreover, data bases that are nearly delightful will require a modest number of messages.(With a reasonable amount of optimization, it is conceivable to approach 2messages per transaction for locally sufﬁcient transactions.)Hence, the number of messages should not bea problem for the common case, that of nearly delightful data bases.4. Hot SpotsHot spots are a problem in all architectures, and there are at least three techniques to dealing with them.1) get rid of them2) divide a hot spot record into N subrecords [ANON84]3) use some implementation of a reservation system [REUT81]It has never been clear to me why the branch balance must be a stored ﬁeld in TP1.In the absence of incredible retrieval volume to this item, it would be better to calculate it on demand.The best way to elimi-nate problems with hot spots is to eliminate hot spots.Unfortunately,there are many hot spots which cannot be deleted in this fashion. These include criti-cal section code in the buffer manager and in the lock manager,and "convo y s" [BLAS79] results from serial hot spots in DBMS execution code.In addition, the head of the log and any audit trail kept by an application are guaranteed to be hot spots in the data base.In such cases the following tactic can usually be applied.Decompose the object in question into N subobjects.For example, the log can be replicated N times, and each transaction can write to one of them.Similarly,the buffer pool and lock table can be decomposed into N stly,the branch balance in TP1 can be decomposed into N balances which sum to the correct total balance.In most cases, a transaction requires only one of the N subobjects, and the conﬂict rate on each subobject is reduced by a factor of N.Of course, the division of subobjects can be hidden from a data base user and applied automatically by the data base designer,whose existence we have specu-lated in Section 3.Lastly,when updates are restricted to increment and decrement of a hot spot ﬁeld, it is possible to use ﬁeld calls (e.g. IMS Fast Path) or a reservation system [REUT82].It is clear that this tactic can be applied equally well to any of the proposed architectures; however, it is not clear that it ever dominates the "divide into subrecords" tactic.Consequently,hot spots should be solvable using conventional techniques.5. Will Concurrency Control Become a Bigger Problem?Some researchers [REUT85] argue that larger transaction systems will generate a thorny concurrency control problem which may affect the choice of a transaction processing architecture. This section argues that such an event will probably be uncommon.Consider the observation of [GRAY81] which asserts that deadlocks are rare in current systems and that the probability of a transaction waiting for a lock request is rare (e.g. .001 or .0001).The conclusion to be drawn from such studies is that concurrency control is not a serious issue in well designed systems today.Consider the effect of scaling such a data base application by a factor of 10.Hence, the CPU is replaced by one with 10 times the throughput.Similarly 10 times the number of drives are used to acceler-ate the I/O system a comparable amount.Suppose 10 times as many terminal operators submit 10 times as many transactions to a data base with 10 times the number of lockable objects.It is evident from queuing theory that the average response time would remain the same (although variance increases) and the proba-bility of waiting will remain the same.The analyis in [GRAY81] can be rerun to produce the identical results. Hence,a factor of 10 scaling does not affect concurrency control issues, and today’s solutions will continue to act as in current systems.Only two considerations cloud this optimistic forcast.First, the conclusion is predicated on the assumption that the number of granules increases by a factor of 10.If the size of a granule remains a con-stant, then the size of the data base must be linear in transaction volume. We will term such a data base problem scalable.Consider the transactions against a credit card data base.The number of transactions per credit card per month is presumably varying slowly.Hence, only a dramatic increase in the number of cards outstanding (and hence data base size) could produce a large increase in transaction rates.This database problem appears to be scalable.In addition, suppose a ﬁxed number of travel agent transactions are generated per seat sold on a given airline. Consequently,transaction volume is linear in seat volume (assuming that planes are a constant size) and another scalable data base results.One has to think hard to discover nonscalable data bases.The one which comes to mind is TP1 in an environment where retail stores can debit one’s bank account directly as a result of a purchase [ANON84]. Here, the number of transactions per account per month would be expected to rise dramatically resulting in a nonscalable data base.However, increasing the size of a TP1 problem will result in no conﬂicts for the account record (a client can only be initiating one retail transaction at a time) and no conﬂict for the teller record (a clerk can only process one customer at a time).Hence, the only situation with increased conﬂict would be on summary data (e.g.the branch balance).Concurrency control on such "hot spots" should be dealt with using the techniques of the previous section.The following conclusions can be drawn. In scalable data bases (the normal case) concurrency con-trol will remain a problem exactly as difﬁcult as today.In nonscalable data bases it appears that hot spots are the main concurrency control obstacle to overcome. Hence, larger transaction systems in the best case present no additional difﬁculties and in the worst case aggravate the hot spot problem.6. CONCLUSIONSIn scalable, tunable, nearly delightful data bases, SN systems will have no apparent disadvantages compared to the other alternatives. Hence the SN architecture adequately addresses the common case. Since SN is a nearly free side effect of a distributed data base system, it remains for the advocates of other architectures to demonstrate that there are enough non-tunable or non-scalable or non delightful problems to justify the extra implementation complexity of their solutions.REFERENCES[ANON84] Anon et. al., "A Measure of Transaction Processing Power", unpublished working paper.[BLAS79] Blasgen,M. et. al., "The Convo y Phenomenon," Operating Systems Review, April 1979.[GRAY81] Gray,J.et. al., "A Straw Man Analysis of Probability of Waiting and deadlock,"IBM Research, RJ3066, San Jose, Ca., Feb 1981.[REUT82] Reuter,A., "Concurrency on High-Trafﬁc Data Elements," ACM-PODS, March 1982.[REUT85] Reuter,A., (private communication).[WONG83] Wong, E. and Katz, R., "Distributing a Data Base for Parallelism," ACM-SIGMOD, May 1983.。

NVIDIA Quadro 系列产品介绍与功能说明书

Large Scale Visualization Ian Williams & Steve Nash, PSG Applied EngineeringAgenda•Intro –Quadro Solutions•High Resolution & HDR Displays and Implications •Stereo•HDR•Implications of Multiple display channels •Addressing Multiple GPUs•SLI Mosaic mode•Combining T echnologiesQuadro Visual Computing Platform NVIDIAQuadro Plex VCSNVIDIA SLI NVDIA G-Sync NVIDIA HD SDI SceniX Scene Graph C CUDA OpenCL 30-bit Color mental ray reality server PhysX CompleXMulti-GPU OptiX InteractiveRay TracingSLI Mosaic Mode SLI Multi OS NVIDIA CUDAQuadro FX FamilyProduct SegmentTargetAudienceKey AdditionalFeaturesQuadroSolutionEstimatedStreet PriceUltra High-End 4D Seismic Analysis4D Medical Imaging+ 4GB GPU Memory+ 240 CUDA Parallel CoresQuadroFX 5800$ 3,299High-End Digital Special EffectsProduct Styling+ G-Sync+ SLI Frame RenderingQuadroFX 4800$ 1,799High-End High End MCADDigital EffectsBroadcast+ SDI+ Stereo+ SLI Multi-OSQuadroFX 3800$ 899Mid-Range Midrange CADMidrange DCC+25% better Perf than FX 580QuadroFX 1800$ 599Entry Volume CADVolume DCC+30% better performancethan FX 380+ 30-bit ColorQuadroFX 580$ 149EntryVolume CADVolume DCCProductivity Apps+50% Better Performancethan FX 370QuadroFX 380$ 99Quadro SystemsProduct SegmentTargetAudienceKey AdditionalFeaturesQuadroSolutionEstimatedStreet Price1U Rackmount Offline & RemoteRenderingFour GPUs16 GB total GPUMemoryTeslaS1070$ 9,000Desksideor3U RackableSeismic AnalysisProduct StylingScalable Graphics2 GPUsSLI Mosaic Mode-Easy 4KCompleXOptiXQuadroPlex2200 D2$ 10,750AXE –Engine Relationships CgFX API Open SceneGraph AXEReachAXE Flexibility OptiX ray tracing engine CompleX scene scaling engine QBStereo API 30-bit & SDI APICustom Applications AXE Center SceniXscenemanagement engineNon-GraphicApplicationsApplication Acceleration Engines -Overview•SceniX–scene management engine–High performance OpenGL scene graph builtaround CgFX for maximum interactive quality–Provides ready access to new GPU capabilities & engines•CompleX–scene scaling engine–Distributed GPU rendering for keeping complex scenes interactive as they exceed frame buffer limits–Direct support for SceniX, OpenSceneGraph, and soon more•OptiX–ray tracing engine–Programmable GPU ray tracing pipelinethat greatly accelerates general ray tracing tasks –Supports programmable surfaces and custom ray data 15GB Visible Human model from N.I.H.Autodesk Showcase customer example OptiX shader exampleWhy use Large Scale Visualization?•Quality•Detail•Pixel real estate•Stereo•Immersive experience•Industry specific needs•…….Display Technologies•Panels•Industry focused –e.g. medical, video •Projectors•Multiple Panels•Multiple ProjectorsImages courtesy of HP, Sony, Barco, Mechdyne,Large Scale VisualizationBeyond 8 DVI Dual Link Requires Clustered PCs with Quadro G-Sync to synchronize displays and Multi GPU aware software.1-2 DVI 2-4 DVI4-8 DVI> 8 DVIApplications written to run on a single display just work across larger display formats.GPUs Displays Linear Performance increase with Quadro Plex Quadro FX GraphicsQuadro G-Sync Card 124148Any Application Runs (Does not need to bemulti GPU aware)•Performance•Stereo•“Mechanics” of >8bit per component •Multiple display channels•OS impact•Synchronization•ClusteringImplications of High Resolution and HDR•GPU memory•3840x2160 desktop at 16x FSAA ~400MB of framebuffer .•Performance•Fill-rate•Window system implications•T exture size & depth•16 bit per componentPerformance Implications of High resolutions & HDR•Consumer Stereo Drivers (3DVision)•Stereo separation from single stream•OpenGL Quad Buffered Stereo•Application has explicit control of the stereo image•Active •Passive Stereo L, R, L, R, L, R, ……L, L, L, L, L, L, ……R, R, R, R, R, R, ……“Mechanics” of >8bit per component•Possible using both DVI or Display Port •Display Port much easier•T extures etc. need to be >8bit per component •FP16, I16 (G8x GPUs and beyond)•RGBA, LA, L•Full screen only•Desktop, GUI, etc will not be correctly displayed •Format specific to display device•Outline:•Configure double-wide desktop•Significantly easier if exported by the EDID•Create full-screen window•Render to off-screen context• E.g. OpenGL FBO•Draw a textured quad•Use fragment program to pack pixels -display device specific-cont16 bit per componentR G BOff-screen buffer8 bits 2 bits8 bit per componentR G B R G BFull-Screen Window-cont16 bit per componentR G BOff-screen buffer8 bits 2 bits8 bit per componentR G B R G BFull-Screen Window02048HDR and Display Port•Requires native Display Port GPU•Desktop will be display correctly (in 8bit)•Outline:•Open 10bit per component Pixel Format/Visual •RenderMultiple Display ChannelsWhy multiple display channels?•Resolutions becoming larger than channel bandwidths•Sony, JVC 4K projectors•Barco and Mitsubishi panels•…….First a couple of questions:•Which OS -Windows or Linux?•Level of application transparency:•Driver does everything?•Application willing to do some work?Implications of Multiple Display Channels•Attach Multiple Monitors using Display Properties •Extend the Desktop to each GPU•Ensure ordering is correct for desired layout•Adjust Resolutions and Refresh Rates•Displays using Refresh Rates <48Hz can be problematic •Synchronizing displays requires G-sync cardThings you don’t intend are also possibleThings to note:•Windows can be opened anywhere on (and off) the complete desktop •Windows can span display boundaries•However maximizing will lock to one display•Where the window centroid is located•Likewise full screen windows•WGL Desktop size is considered outer rectangle spanning all displays •Driver will typically send data to all GPUs (in case window is moved, etc.)•GPU Affinity OpenGL extension solves thisDISPLAY_DEVICE lDispDev;DEVMODE lDevMode;lDispDev.cb = sizeof(DISPLAY_DEVICE);if (EnumDisplayDevices(NULL, 0, &lDispDev, NULL)) {EnumDisplaySettings(lDispDev.DeviceName, ENUM_CURRENT_SETTINGS, &lDevMode);}g_hWnd1 = createWindow(hInstance, lDevMode.dmPosition.x, lDevMode.dmPosition.y, X0, Y0);if (!g_hWnd1) { MessageBox(NULL, "Unable to create first window(s).", "Error", MB_OK); return E_FAIL;}if (EnumDisplayDevices(NULL, 1, &lDispDev, NULL)) {EnumDisplaySettings(lDispDev.DeviceName, ENUM_CURRENT_SETTINGS, &lDevMode);}g_hWnd2 = createWindow(hInstance, lDevMode.dmPosition.x, lDevMode.dmPosition.y, X1, y1);if (!g_hWnd2) {MessageBox(NULL, "Unable to create second window(s).", "Error", MB_OK); return E_FAIL;}Verify first display exists and get display settingsCreate Window on first display Verify second display exists and get display settings Create Window on second display•WGL extension (WGL_NV_gpu_affinity), core OpenGL not touched •GLX definition in the works•Application creates affinity-DC•HDC wglCreateAffinityDCNV(const HGPUNV *phGpuList);•Special DC that contain list of valid GPUs -> affinity mask•Affinity mask is immutable•Application creates affinity context from affinity-DC•As usual with RC = wglCreateContext(affinityDC);•Context inherits affinity-mask from affinity-DC•Application makes affinity context current•As usual using wglMakeCurrent()•Context will allow rendering only to GPU(s) in its affinity-maskWindowsGPU Affinity•Affinity context can be made current to:•Affinity DC•Affinity mask in DC and context have to be the same•There is no window associated with affinity-DC. Therefore:•Render to pBuffer•Render to FBO•DC obtained from window (regular DC)•Rendering only happens to the sub-rectangle(s) of the window that overlap the parts of the desktop that are displayed by the GPU(s) in the affinity mask of the context.•Sharing OpenGL objects across affinity contexts only allowed if affinity mask is the same•Otherwise wglShareLists will failWindows cont.GPU Affinity•Enumerate all GPUs in a system•BOOL wglEnumGpusNV(int iGpuIndex, HGPUNV *phGpu);•Loop until function returns false•Enumerate all display devices attached to a GPU •BOOL wglEnumGpuDevicesNV(HGPUNV hGpu, int iDeviceIndex, PGPU_DEVICE lpGpuDevice);•Returns information like location in virtual screen space•Loop until function returns false•Query list of GPUs in an affinity-mask •BOOL wglEnumGpusFromAffinityDCNV(HDC hAffinityDC,int iGpuIndex, HGPUNV *hGpu);•Loop until function returns false•Delete an affinity-DC•BOOL wglDeleteDCNV(HDC hdc);Windows cont.GPU Affinity#define MAX_GPU 4int gpuIndex = 0;HGPUNV hGPU[MAX_GPU];HGPUNV GpuMask[MAX_GPU];HDC affDC;HGLRC affRC;while ((gpuIndex < MAX_GPU) && wglEnumGpusNV(gpuIndex, &hGPU[gpuIndex])) {gpuIndex++;}GpuMask[0] = hGPU[0];GpuMask[1] = NULL;affDC = wglCreateAffinityDCNV(GpuMask);<Set pixelformat on affDC>affRC = wglCreateContext(affDC);wglMakeCurrent(affDC, affRC);<Create a FBO>glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, b);<now render>GPU Affinity –Render to Off-screen FBOCreate list of the first MAX_GPUs in the systemCreate an affinity-DC associated with first GPU Make the FBO current to render into itMultiple Displays -Linux•T wo traditional approaches depending on desired level of application transparency or behavior:•Separate X screens•3D Windows can’t span X screen boundaries•Location of context on GPU allows driver to send datato only that GPU•Xinerama•One large virtual desktop•3D Windows can span X screen boundaries•Will typically result in driver sending all data to allGPUs (in case window moves)Multiple Displays -Linux•Use nvidia-xconfig to create customized xorg.conf•nvidia-settings provides full featured control panel for Linux•Drivers can capture EDID•Useful when display device hidden behind KVM or optical cable •Synchronizing multiple displays requires G-sync cardSynchronizing Multiple Displays•Requires G-sync•Synchronize vertical retrace•Synchronize stereo field•Enables swap barrier•OpenGL Extensions•Windows: WGL_NV_Swap_Group•Linux:GLX_NV_Swap_GroupNameNV_swap_groupDependenciesWGL_EXT_swap_control affects the definition of this extension.WGL_EXT_swap_frame_lock affects the definition of this extension. OverviewThis extension provides the capability to synchronize the buffer swapsof a group of OpenGL windows. A swap group is created, and windows are added as members to the swap group. Buffer swaps to members of the swap group will then take place concurrently.This extension also provides the capability to sychronize the bufferswaps of different swap groups, which may reside on distributed systems on a network. For this purpose swap groups can be bound to a swap barrier.This extension extends the set of conditions that must be met beforea buffer swap can take place. BOOL wglJoinSwapGroupNV(HDC hDC,GLuint group);BOOL wglBindSwapBarrierNV(GLuint group,GLuint barrier);BOOL wglQuerySwapGroupNV(HDC hDC,GLuint *group);GLuint *barrier);BOOL wglQueryMaxSwapGroupsNV(HDC hDC,GLuint *maxGroups,GLuint *maxBarriers);BOOL wglQueryFrameCountNV(HDC hDC,GLuint *count);BOOL wglResetFrameCountNV(HDC hDC);NameNV_swap_groupOverviewThis extension provides the capability to synchronize the buffer swapsof a group of OpenGL windows. A swap group is created, and windows are added as members to the swap group. Buffer swaps to members of the swap group will then take place concurrently.This extension also provides the capability to sychronize the bufferswaps of different swap groups, which may reside on distributed systems on a network. For this purpose swap groups can be bound to a swap barrier.This extension extends the set of conditions that must be met beforea buffer swap can take place. Bool glxJoinSwapGroupNV(Display *dpy,GLXDrawable drawable, GLuint group); Bool glxBindSwapBarrierNV(Display *dpy,GLuint group,GLuint barrier);Bool glxQuerySwapGroupNV(Display *dpy,GLXDrawable drawable, GLuint *group);GLuint *barrier);Bool glxQueryMaxSwapGroupsNV(Display *dpy,GLuint screen, GLuint *maxGroups,GLuint *maxBarriers);Bool glxQueryFrameCountNV(Display *dpy,GLuint *count);Bool glxResetFrameCountNV(Display *dpy);Using G-syncRecommendations:•Control Panel will cause regular CPU contention •Polls hardware status•Use additional synchronization mechanisms in addition to swapbarrier–Broadcast frame countMultiple Displays made easy!•Enables transparent use of multiple GPUs on multiple displays •Enables a Quadro Plex(multiple GPUs) to be seen as one logical GPUby the operating system•Applications ‘just work’ across multi GPUs and multi displays•Works with OGL, DX, GDI etc•Zero or minimal performance impact for 2D and 3D applications compared with a single GPU per single display •Doesn’t support multiple View FrustumsDetails•Quadro Plex only•Operating System support•Windows XP, Linux, 32bit and 64bit •Vista/Win 7 soon•Maximum desktop size = 8k X 8k •FSAA may exacerbate desktop size •Compatible with G-sync•Clustering tiled displays •Supports StereoConfigurations0.10.20.30.40.50.60.70.80.91 1 screen4 screens 8 screensPerformance Hit for Multiple DisplaysViewperf 10.0SLI Mosaic Performance AdvantageViewperf 10.00.20.40.60.811.21 screen4 screens, Mosaic8 screens, MosaicProgrammatically controlling Mosaic Mode•NvAPI provides direct access to NVIDIA GPUs anddrivers on Windows platforms•Nvidia Control Panel GUI shows tested configurations •More advanced configuration possible through NvAPIProgramatically controlling Mosaic Mode (cont’d)NV_MOSAIC_TOPOLOGY topo; // struct defines rowcount, colcount& gpuLayoutNV_MOSAIC_SUPPORTED_TOPOLOGIES supportedTopoInfo; // list of topologies// Get List of Supported Topologies and display resolutionsnvStatus= NvAPI_Mosaic_GetSupportedTopoInfo(&supportedTopoInfo, type);// Set Mosaic Mode for a given topologynvStatus= NvAPI_SetCurrentMosaicTopology(&topo);// To Disable Mosaic ModenvStatus= NvAPI_EnableCurrentMosaicTopology(0);Beyond SLI Mosaic Mode•Can combine Mosaic for partial set of all GPUs •Use CUDA or GPU Affinity for non-display GPUs •Requires “Manual” Configuration•Combine Mosaic with CompleX Application Acceleration EngineSummary•Demand for Large Scale Viz& HDR technologies are being driven by economics• E.g. Digital Prototypes significantly less expensive than physicalprototypes however demand high quality and realism•Very large resolutions are de-facto standard for collaborative and large venue installations•Pixel bandwidth requirements still require multiple channels, even with Display Port•Some large venue displays are HDR capableSummary –cont.•Be aware of performance implications when using multiple GPUs–Use affinity/Separate Xscreens•Solutions like SLI Mosaic Mode extends the reach of Large Scale Visualization•Combining solutions enables unprecedented realism and interactivity–CompleX+ Mosaic = interactive massive datasets–OptiX+ Mosaic = unprecedented realism on a large scale–Compute + viz cluster = flexible utilization with massive compute powerThank You!•Feedback & Questions.。

晨读英语美文

晨读英语美文晨读英语美文1参考翻译我的祖父母认为, 人要么诚实, 要么不诚实. 不可能居于两者之间. 他们在起居室的墙上挂着一幅简短的箴言: “生活就像刚被白雪覆盖的原野, 无论走到哪儿, 都会出现我的脚印.” 他们从不在口头上做文章----而是身体力行去实践这句箴言.他们本能地懂得, 诚实意味着有个人道德标准, 既不见利忘义, 也不趋炎附势. 诚实是评判举止的内在标准. 遗憾的是, 当今社会越练越缺少诚信, 而它却是社会每一个领域的`真正底线, 也是我们对自己的必须要求.检验这种价值, 要依据我所谓的”诚实三和弦”, 它包括三个主要原则: 面对个人压力, 要坚定信念. 有这样一个故事: 在一个著名的医院, 一个外科护士第一天到医疗组上班. 在一个腹部手术中, 她负责对所有的器材进行清点时, 对外科医生说: “您只取出11块纱布, 可我们用了12块, 必须找到最后一块.“我都取出来了,” 医生断言, “现在要缝合刀口了.”“您不能这样, 先生,” 新来的护士抗议道, “得想想病人,” 外科医生抬起脚, 笑着给护士看第12块纱布.他告诉护士: “不论你是在这所医院还是其他地方, 都会干得很好的.” 当你确定自己正确时, 就不能退缩.经常赞扬那些值得肯定的人. 不要惧怕那些比你更有见解, 更机智的人.戴维.奥格尔维是奥格尔维和马瑟广告公司的创始人, 他给每一个新上任的部门经理送一个俄罗斯式套娃, 里面有一次变小的5个娃娃. 最小的一个里面有他的留言, 清晰地告诉他们:“如果我们雇用的每个人都比我们矮小, 我们就会成为侏儒公司. 但是, 反过来, 如果雇用的人都很高大, 奥格尔维和马瑟将成为巨人公司.” 正是这样, 这个公司后来成为世界上最达最有声望的广告公司.真诚, 坦率地展现真我风采. 只有缺乏核心价值观的人才会依靠外界因素----他们的外貌或地位 ---- 使自我感觉良好. 不可避免地, 他们会掩饰内心, 不去培养自己的核心价值, 也不注重自我成长.所以, 要做你自己. 不要掩饰生活中不尽人意的方方面面, 要坚强地面对生活中的困难时刻. 换言之, 面对现实, 要成熟地应对生活中的种种挑战.晨读英语美文2When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation.We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and thepursuit of Happiness. —That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, —That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness. Prudence, indeed, will dictate that Governments long established should not be changed for light and transient causes; and accordingly all experience has shown, that mankind are more disposed to suffer, while evils are sufferable, than to right themselves by abolishing the forms to which they are accustomed.But when a long train of abuses and usurpations, pursuinginvariably the same Object evinces a design to reduce them under absolute Despotism, it is their right, it is their duty, to throw off such Government, and to provide new Guards for their future security. —Such has been the patient sufferance of these Colonies; and such is now the necessity which constrains them to alter their former Systems of Government. The history of the present King of Great Britain [George III] is a history of repeated injuries and usurpations, all having in direct object the establishment of an absolute Tyranny over these States. To prove this, let Facts be submitted to a candid world.晨读英语美文3Knowledge is one thing, virtue is another; good sense is not conscience, refinement is not humility, nor is largeness and justness of view faith. Philosophy, however enlightened, however profound, gives no command over the passions, no influential motives, no vivifying principles. Liberal Education makes not the Christian, not the Catholic, but the gentleman. It is well to be a gentleman, it is well to have a cultivated intellect, a delicate taste, a candid, equitable, dispassionate mind, a noble and courteous bearing in the conduct of life—these are the connatural qualities of a large knowledge; they are the objects of a University. I am advocating, I shall illustrate and insist upon them;but still, I repeat, they are no guarantee for sanctity or even for conscientiousness, and they may attach to the man of the world, to the profligate, to the heartless, pleasant, alas, and attractive as he shows when decked out in them. Taken by themselves, they do but seem to be what they are not; they look like virtue at a distance, but they are detected by close observers, and in the long run; andhence it is that they are popularly accused of pretense and hypocrisy, not, I repeat, from their own fault, but because their professors and their admirers persist in taking them for what they are not, and are officious in arrogating for them a praise to which they have no claim. Quarry the granite rock with razors, or moor the vessel with a thread of silk, then may you hope with such keen and delicate instruments as human knowledge and human reason to contend against those giants, the passion and the pride of man.晨读英语美文4富足是一种生活方式。

SSMA for Oracle v7.6.0 快速启动指南说明书

Step-by-Step Guide toRunning SSMA for Oraclev7.6.0Prepared byRakesh DavanumSolution Architect, DMJ Engineering ProgramJonathon FrostSolution Architect, DMJ Engineering ProgramThis document is provided “as-is”. Information and views expressed in this document, including URL and other Internet Web site references, may change without notice.Some examples depicted herein are provided for illustration only and are fictitious. No real association or connection is intended or should be inferred.This document does not provide you with any legal rights to any intellectual property in any Microsoft product. You may copy and use this document for your internal, reference purposes.© 2018 Microsoft. All rights reserved.This document is meant to be used as a Quick Start Guide to migrate schema & data from Oracle to Azure SQL DB using SSMA for Oracle v7.6.0. The complete documentation can be found athttps:///en-us/sql/ssma/oracle/sql-server-migration-assistant-for-oracle-oracletosqlSteps1.)Ensure Oracle Client Drivers are already installed on the Windows machine•For example, if connecting to Oracle 11g, ensure Oracle Client Driver for 11g or higher is installed2.)Install SSMA for Oracle v7.6.0 from this link: https:///en-us/download/details.aspx?id=54258•Install on a Windows machine with network access to the Oracle instances.•When the target is SQL Server On-Prem or IaaS, then in addition to installing SSMA, the SSMA Extension pack needs to be installed on the computer that isrunning SQL Server: https:///en-us/sql/ssma/oracle/installing-ssma-components-on-sql-server-oracletosql3.)Open SSMA for Oracle v7.6.04.)Create a new project using the File menu5.)In the New Project dialog, specify the Project Name & Location. Make sure to select theMigrate To drop down as SQL Azure as the target platform and click OK.6.)Click Connect to Oracle7.)Enter your Oracle server info then click Connect8.)Once the connection is established, all the Oracle Schemas and Objects are listed inOracle Metadata Explorer9.)Click on the schema that you want to convert, to show the details of the schema on the rightdetails pane10.)C lick on Type Mapping to confirm the source to target data type mapping. Use the Editbutton to make changes (if needed) to the default mapping shown.11.)E xpand Schemas and select the schema you want to migrate. Use the Create Reportbutton on the top ribbon or right click on the schema name and choose Create Report to generate the SSMA migration report. (You may be prompted to re-enter the credentials and reconnect to the source system).12.)O nce the report is created, the HTML report will be opened in a Web Browser13.)A t this point you can save the project if you want to do some offline analysis. ChooseSave Project from the File menu.14.)T his will bring up the Save Metadata dialog box which will let you select the schemasthat you want offline information about so that if you share the SSMA project with others they will not need to connect to the source system for offline analysis. Select theschemas you want and choose Save. (You may be prompted to re-enter the credentials and reconnect to the source system).15.)O nce the report is generated, the next step is to Convert Schema which will create thecorresponding schema code for the target environment – SQL Azure DB. Click onConnect to SQL Azure on the top ribbon to connect to your target environment.16.)S pecify the SQL Azure DB connection details in the dialog box17.)O nce the connection is successful, all the objects in SQL Azure DB are listed in SQL AzureMetadata Explorer18.)S elect the schema you want to convert in Oracle Metadata Explorer and then click onConvert Schema button on the top ribbon or right click on the schema and choose Convert Schema19.)O nce the schema is converted, the converted objects will be listed under the SQL AzureMetadata Explorer. The schemas are just created in SSMA but are not actuallycommitted/persisted in the target SQL Azure DB at this point.20.)T he schema creation script for the target SQL Azure DB can now be saved at this pointfor future reference or offline reading. Select the schemas in SQL Azure Metadata Explorer for which you want to save the script then right click on Schemas and choose Save as Script21.)N ow that the schema is converted to target Azure SQL DB, the same can becommitted/persisted into the target system. Under SQL Azure Metadata Explorer, choose the schemas that you want to commit and the 2 assemblies starting with the nameSSMA4Oracle, right click on the database name then choose Synchronize withDatabase22.)T his will bring up the dialogue box showing the differences in Local Metadata vsDatabase. Click on the button Hide Equal Objects at the top to see only the difference.23.)C lick on OK to initiate synchronizing with database24.)O nce the Synchronize with Database operation is complete, connect to the target AzureSQL DB using a different tool like SSMS. Expanding the different objects under thedatabase should now list all the new objects that were converted from Oracle.25.)N ow that the schema is created in the target Azure SQL DB, we can proceed to migratingthe actual data from Oracle. Under Oracle Metadata Explorer, select the schema forwhich you want to migrate the data. Right click on the schema name and chooseMigrate Data. (May be prompted to connect to Oracle & Azure SQL DB)•Note: When the target is SQL Server On-Prem or IaaS, follow the instructions provided at https:///en-us/sql/ssma/oracle/migrating-oracle-data-into-sql-server-oracletosql to ensure Server Side Data Migration settingsare setup up correctly before initiating data migration.26.)O nce the data migration is complete, a Data Migration Report is shown listing all thetables and the total rows that was migrated.27.)C lick on Save Report if you want an offline copy of the Data Migration Report which canbe save in a CSV format28.)O nce the data migration is complete, connect to the target Azure SQL DB using adifferent tool like SSMS and query a table to confirm that the data was transferred successfully from Oracle to Azure SQL DB.Feedback and suggestionsIf you have feedback or suggestions for improving this data migration asset, please contact the Data Migration Jumpstart Team (******************************). Thanks for your support!Note:For additional information about migrating various source databases to Azure, see the Azure Database Migration Guide.。

Java笔试常见英语题(附答案)

Q1. How could Java classes direct program messages to the system console, but error messages, say to a file?.Java中如何将程序信息导航到系统的console，而把错误信息放入到一个file 中？The class System has a variable out that represents the standard output, and the variable err that represents the standard error device. By default, they both point at the system console. This how the standard output could be re-directed:Stream st = new Stream(new FileOutputStream("output.txt"));System.setErr(st); System.setOut(st);系统有一个展现标准输出的out变量，以及一个负责标准错误设置的err变量，默认情况下这两个变量都指向系统的console，这就是标准输出如何能被改变方向（就是改变信息的输出位置）。

* Q2. What's the difference between an interface and an abstract class?抽象类和接口的区别：A. An abstract class may contain code in method bodies, which is not allowed in an interface. With abstract classes, you have to inherit your class from it and Java does not allow multiple inheritance. On the other hand, you can implement multiple interfaces in your class.抽象类中可能会含有带有方法体的一般方法，而这在接口中是不允许的。

详细图文IC5141安装说明

操作系统：CentOS-5.5-i386；虚拟机：VMwareWorkstation-6；软件：cadence ic5141 USR6和Base 1、安装CentOS-5.5，在软件定制部分需要立即定制，然后选择旧版支持，Java软件等等。

软件定制选择如下：桌面环境全选；应用程序全选；开发全选；基本系统全选；虚拟化全选；服务器选windows文件服务器，万维网服务器，打印支持。

2、由于CentOS-5.5的tar-1.15.1，sort-5.97，expr-5.97版本过高，需要用tar-1.14，sort-5.2.1，expr-5.2.1才能正常解压安装，而这几个程序可以在CentOS-4.8中找到。

之后，使用root账户登录，分别对应替换高版本的/bin/tar，/bin/sort，/usr/bin/expr。

此处记得备份CentOS-5.5的原件哦！（另外，我也给出了CentOS-4.8和CentOS-5.5中的程序，以便大家下载）3、新建一个用户kury（这个根据喜好，但此处我用kury说明），在/home/kury目录中新建文件夹cadence_install。

之后，在cadence_install里面新建文件夹base，update，用于存放IC5141的base 包跟update包。

base包在电驴上有：ed2k://|file|Cadence.Base.IC5141.Lnx86.3CDs[.ck].rar|1201102747|A4DE108A291CC6BDD86D8E46D3E5 A677|h=PWYDUTUBIMHDVZ2EDLNMRNAKGAVIWJFA|/USR6 update包在论坛里有：/viewthread.php?tid=219912&highlight=USR6此处需要说明，在CentOS-5.5下安装必须要有这两个包，不然不能运行cadence！！！4、解压：Cadence.Base.IC5141.Lnx86.3CDs[.ck] 得到三个base包，一个cadence_license_full.dat；解压：Update_IC50.46.006_lnx86得到四个update包。

我和我的朋友的高光时刻英语作文

Title: The Highs of Friendship: A Chronicle of Joy In the journey of life, there are moments that stand out as beacons of light, illuminating the beauty and depth of our connections with others. These high points, or "highlight reels," often come in the form of shared experiences with friends—those cherished individuals who walk alongside us through thick and thin. In this essay, I will delve into a memorable moment that my friend and I experienced together, exploring the significance of such instances and their enduring impact on our lives.It was a crisp autumn evening, the kind that fills the air with a hint of woodsmoke and the promise of changing seasons. My friend Alex and I had planned for weeks to attend a music festival set amidst the rolling hills of our hometown. Neither of us had ever been to a festival of this scale before, so the build-up was filled with a mixture of anticipation and curiosity. We both love live music, and the idea of being surrounded by the energy of thousands of music lovers was electrifying.As we arrived at the venue, the first thing that struck us was the sheer diversity of people. There were young couples holding hands, families with kids bouncing with excitement, groups of friends like us, and solo attendees soaking up the atmosphere. The festival was a melting pot of cultures, fashions, and attitudes—a microcosm of the world in all its vibrant glory.The music was the heartbeat of the festival, each beat pulsing through our veins and synchronizing our movements. We lost ourselves in the performances, singing along to every word, swaying to the rhythm, and occasionally closing our eyes to better absorb the melodies. There was a moment during a particularly soulful ballad when Alex and I locked eyes, and without saying a word, we knew we were both feeling the same profound emotion. It was as if the music had created a bridge between our spirits, connecting us on a level beyond words.One of the most memorable parts of the day was when we stumbled upon a small stage tucked away from the main hubbub. A local band was playing there,and they had drawn a sizable crowd despite their less prominent placement. Alex and I found ourselves completely enraptured by their authenticity and passion. After their set, we had the chance to meet them and chat about their music. It was a stark reminder of the importance of supporting emerging artists and recognizing talent in its rawest form.As the night sky enveloped the festival grounds and the lights became more prominent than the stars above, we decided to take a walk to soak in the atmosphere. The pathways were lit with fairy lights, creating an otherworldly feel. We encountered various performers, from street musicians to breakdancers, adding to the carnivalesque ambiance. Alex and I laughed and joked, enjoying the freedom of being anonymous in a sea of strangers. We stopped to watch a group of performers acrobatically spinning fire-lit objects, mesmerized by their skill and bravery.At one point, we came across a food stall selling exotic delicacies—a feast for the senses. We decided to indulge in some spicy Thai noodles, savoring the flavors and the heat that warmed us from within.Sharing food has always been a way for us to bond, and that simple act of passing a dish back and forth reinforced the comfort and ease of our friendship.As the night wore on, we returned to the main stage just as a renowned band took to the platform. The crowd erupted into cheers, and we found ourselves jumping up and down to the infectious beat. Time seemed to stand still as we danced, forgetting our worries and embracing the pure joy of the moment. It was then that I looked over at Alex, and despite the noise around us, I could see the broad smile on his face and the sparkle in his eyes. It was a look that said, "I am exactly where I am meant to be."The festival ended not with a whimper but a roar, as fireworks lit up the sky, painting streaks of light that reflected in our eyes. Alex and I walked back to our car with the afterglow still enveloping us. We didn't say much, but the silence was comfortable, filled with the unspoken knowledge of an experience shared and a bond strengthened.Reflecting on this high point in our friendship, I realize that it wasn't just about the music, the food, orthe spectacle. It was about the connection that Alex and I share—a connection that grows richer with each shared adventure. These highlight reels are important because they serve as touchstones for our memories, reminding us of the happiness that can be found in the company of good friends. They are the times that we look back on during difficult days, giving us strength and warmth. They are the stories that we recount to others, showcasing the beauty of human connection.In conclusion, the joyous moments spent with friends are treasures to be cherished. They are the peaks that make up the landscape of our lives, providing us with a sense of accomplishment, camaraderie, and belonging. They are the glue that holds our friendships together, binding us through the highs and lows of life. And as we continue on this journey, Alex and I will undoubtedly collect more high points to add to our chronicle of joy, each one a testament to the enduring power of shared experiences and the unbreakable bond of friendship.。

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object orientation, i.e. a specific mode of information structuring, mainly characterised by the association of operations to data, by dynamic instance creation and by inheritance of properties, distribution, i.e. the ability to execute computational processes that span a number of physical nodes on a network, and to move objects from one node to another.
2. Guide synchronization model
In Guide, synchronization is specified as a set of constraints associated with objects, not as primitives appearing within activities. This is consistent with the object approach, since the specification of the synchronization constraints is concentrated in the class that describes the object instead of being spread out in methods that use the object. In addition, this synchronization specification is shared by all instances of the class. Synchronization is specified as a set of activation conditions, which are similar to Dijkstra’s guarded commands: an activation condition is attached to a method, and must be satisfied before the execution of this method may start. This condition is expressed as a function of both the internal state of the object and the parameters of the invocation. If no activation condition is attached to a method, then the execution of this method is unconstrained.
0967-1846/95/020112+14$19.500 1995 The Brib‘sh Computer Society, The Institution of Electrical Engineers and IOP Publishing Ltd
Synchronising shared objects
1. Introduction
A major feature of many information systems is &to sharing by a number of concurrent activities. Concurrent access to shared data must be controlled in order to guarantee that the data remain in a consistent state. This problem has been known for a long time, and a number of solutions have been proposed. However, two new features have appeared in recent systems:
Many synchronization tools have been proposed for modular or distributed environments (an overview is available in (Grass 1986)). These mechanisms include monitors (Hoare 1974), constructs based on synchronous message passing and guarded commands (Dijkstra 1973, such as DP [Brinch Hansen 781 or CSP (Hoare 1978), and path expressions (Campbell 1974). In comparison, few synchronization mechanisms have been proposed for object-oriented systems, mainly because few 0-0system support concurrency and shared objects. Emerald (Black 1986) provides a ‘monitor’ construct allowing mutual exclusion to a set of data and associated methods. TrellislOwl (Moss 1987) proposes a similar tool, based on locks and wait queues. In Hybrid Wierstrasz 1987). delay queues allow scheduling activities in the same way as condition variables in monitors. All these mechanisms are limited and do not allow canonical synchronization schemes to be expressed easily. Another powerful synchronization mechanism is the ‘mediator’ (Grass 1986), based on guarded commands with statements allowing mutually exclusive service calls
t Email: Michel.RiveiIl@imag.fr.
(the exec statement), or asynchronous calls (the spawn statement), and return with the release statement. These statements support the activity scheduling within an object to be controlled. Guards-express pre-conditions that can be programmed using both $e variables of the mediator, the service requested by the client (name of the service, value of the parameters and key identifying the client) and the status of the pending requests. This tool is very powerful, but is very difficult to implement efficiently. In addition, it is far too complex for most o the usual synchronization schemes. f This analysis motivated us to define a mechanism with an exprqsive power between the locks and the mediators. The synchronization mechanism presented in this paper has been designed for the distributed object-oriented system Guide (Decouchant 1991), implemented as a joint project between the University of Grenoble and Groupe Bull Research Department. This system also embodies the object-oriented architecture defined in the Comandos project under the ESPRIT Program supported by the Commission of the European Communities (Cahill 1993). The Guide language provides seong static typing; this allows programming errors to be detected at compiletime, based on type checking. Types (interface descriptions) are distinct from classes (instance generators); a type may be implemented by several different classes. More details on the language can be found in (Balter 1994). A compiler for the Guide object-oriented language and a runtime system were developed both on top of Unix and directly on top the Mach micro-kernel technology (Hagimont 1994). This runtime provides object sharing and persistency with Wsparent distribution of naming, storage and execution. This paper is organized as follows. Section 2 describes our synchronization model and its integration within the Guide language. This section also presents some canonical examples to illustrate the use of the synchronization facilities. Section 3 is a survey of some concurrent objectoriented languages, compared with our approach. Finally section 4 outlines the main implementation problems.