weblogic故障分析模式培训_HANG

Execute Thread Pool
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...Refresher: WLS Execute Threads
A server has 15 threads (default) to process
both client requests and network traffic.
server hang.
Module HANG
WebLogic Server: Generic Server Hang Pattern
At the end of this module you will be able to:
Identify a hung server. Understand why a server might hang. Investigate the cause of a hung server. Solve common server hang problems.
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Server Hang Investigation
Troubleshooting Checklist
Generic Server Hang Pattern
© 2004 BEA Systems, Inc.
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Generic Server Hang Pattern
This is a generic pattern, which references
One or more hung threads may appear as a
Wait or resource blocking conditions are
An “OK” thread that is waiting for work:
typical causes ofHale Waihona Puke hung threads.9
…Specific Causes of Server Hang…
Application deadlock: –Thread A locks resource1 and then waits to lock resource2, thread B locks resource2 and then waits to lock resource1. –Refer to Application Deadlock Server Hang Pattern.
the following specific server hang patterns:
– – – – – – – – – Thread Usage Server Hang Pattern Garbage Collection Server Hang Pattern Server Hang in Code Optimization Pattern Application Deadlock Server Hang Pattern Server Hang in JDBC Pattern EJB RMI Server Hang Pattern JSP Causes Server Hang Pattern JSP Compilation Server Hang Pattern Sun JVM Bugs Server Hang Pattern.
Generic Server Hang Pattern
© 2004 BEA Systems, Inc.
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Road Map
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Generic Server Hang Pattern
– Refresher: What is a Server Hang? – Symptoms of a Server Hang – Causes of Server Hang
Generic Server Hang Pattern © 2004 BEA Systems, Inc. 8
Specific Causes of Server Hang…
Insufficient threads configured: –All threads are used and none are available for new work –Refer to Thread Usage Server Hang Pattern. Garbage collection (GC) taking too much time: –GC impacts the server’s performance, as processing may pause for its duration. –Refer to Garbage Collection Server Hang Pattern.
– Execute threads, for processing user requests.
Incoming Requests
Execute Queue 1 9 9 9 9 9 9 1 1 Socket Reader Thread Pool
Generic Server Hang Pattern © 2004 BEA Systems, Inc.
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Symptoms of a Server Hang
Requests aren’t processed.
The server appears to be doing nothing at all.
A server may take longer and longer to process
requests, if it is on the way to hanging.
A server: – May crash as a result of a hang, but not always
– Might recover from a hang, eg if resource contention is the cause and the resource eventually becomes free – May remain in a hung state indefinitely, unless some manual action is taken.
–Many remote JNDI lookups cause threads to hang –Refer to EJB RMI Server Hang Pattern.
Generic Server Hang Pattern © 2004 BEA Systems, Inc. 10
…Specific Causes of Server Hang
Generic Server Hang Pattern
© 2004 BEA Systems, Inc.
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Refresher: WLS Execute Threads...
A WLS instance does all processing in thread pools.
Threads are allocated as: – Socket Reader threads, for handing network traffic
If a server
appears to hang, but slowly
recovers:
–Resources become available and processing resumes –This may take an unacceptably long time to occur.
–Refer to Sun JVM Bugs Server Hang Pattern
Generic Server Hang Pattern
© 2004 BEA Systems, Inc.
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Section Review In this section we discussed:
What is a Server Hang? Symptoms of Server Hang.
What Causes a Server Hang?
Generic Server Hang Pattern
© 2004 BEA Systems, Inc.
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Road Map
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Generic Server Hang Pattern
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Server Hang Investigation
JSP compilation: –The server may hang under heavy load
–Refer to JSP Compilation Server Hang Pattern.
Improper JSP settings for servlet times: –For example PageCheckSeconds –Refer to JSP Causes Server Hang Pattern. Sun JVM bugs: –For example in the lightweight thread library
© 2004 BEA Systems, Inc. 3
Generic Server Hang Pattern
Refresher: What is a Server Hang?
A WebLogic Server instance is said to hang,
if it becomes unresponsive.
Generic Server Hang Pattern © 2004 BEA Systems, Inc. 7
Summary of Server Hang Causes
A server hang is often caused by a resource
lack, that inhibits the server processing requests:
JDBC deadlocks: –A database deadlock has occurred –Refer to Server Hang in JDBC Pattern. All threads are waiting for a response to an