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https://issues.apache.org/jira/browse/XMLRPC-168?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12704384#action_12704384
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Alan Burlison commented on XMLRPC-168:
--------------------------------------
Wow, that was quick - thanks a bunch, much appreciated. I'll pull your fix
tomorrow and give it a good hammering. The two variables you identified
(Poolable.shuttingDown and Poolable.task) were the one's I'd noted too, and the
volatile declarations are a neat way of resolving the lock ordering issue that
the various synchronized methods & blocks were causing, so I'm pretty confident
you will have nailed it - I'll let you know the results of my testing. Thanks
again!
> XML-RPC server deadlocks under heavy load
> -----------------------------------------
>
> Key: XMLRPC-168
> URL: https://issues.apache.org/jira/browse/XMLRPC-168
> Project: XML-RPC
> Issue Type: Bug
> Components: Source
> Affects Versions: 3.1.2
> Environment: Soalris
> Reporter: Alan Burlison
> Assignee: Jochen Wiedmann
> Fix For: 3.1.3
>
> Attachments: Client.java, Client.java, Server.java, ThreadPool.java,
> ThreadPool.java
>
>
> When running a XML-RPC server under heavy load, it eventually deadlocks
> inside the thread pool that manages the 'worker' threads which handle the
> individual XML-RPC requests - the classes involved are
> org.apache.xmlrpc.util.ThreadPool and
> org.apache.xmlrpc.util.ThreadPool$Poolable. jstack on the hung process shows:
> ----------
> Found one Java-level deadlock:
> =============================
> "XML-RPC-13":
> waiting to lock monitor 0x08d10bec (object 0xbb6959c0, a
> org.apache.xmlrpc.util.ThreadPool),
> which is held by "XML-RPC Weblistener"
> "XML-RPC Weblistener":
> waiting to lock monitor 0x08d1186c (object 0xbd2ed340, a
> org.apache.xmlrpc.util.ThreadPool$Poolable$1),
> which is held by "XML-RPC-2"
> "XML-RPC-2":
> waiting to lock monitor 0x08d112f4 (object 0xbd2ed570, a
> org.apache.xmlrpc.util.ThreadPool$Poolable),
> which is held by "XML-RPC Weblistener"
> Java stack information for the threads listed above:
> ===================================================
> "XML-RPC-13":
> at org.apache.xmlrpc.util.ThreadPool.repool(Unknown Source)
> - waiting to lock <0xbb6959c0> (a org.apache.xmlrpc.util.ThreadPool)
> at org.apache.xmlrpc.util.ThreadPool$Poolable$1.run(Unknown Source)
> "XML-RPC Weblistener":
> at org.apache.xmlrpc.util.ThreadPool$Poolable.start(Unknown Source)
> - waiting to lock <0xbd2ed340> (a
> org.apache.xmlrpc.util.ThreadPool$Poolable$1)
> - locked <0xbd2ed570> (a org.apache.xmlrpc.util.ThreadPool$Poolable)
> at org.apache.xmlrpc.util.ThreadPool.startTask(Unknown Source)
> - locked <0xbb6959c0> (a org.apache.xmlrpc.util.ThreadPool)
> at org.apache.xmlrpc.webserver.WebServer.run(Unknown Source)
> at java.lang.Thread.run(Thread.java:619)
> "XML-RPC-2":
> at org.apache.xmlrpc.util.ThreadPool$Poolable.isShuttingDown(Unknown
> Source)
> - waiting to lock <0xbd2ed570> (a
> org.apache.xmlrpc.util.ThreadPool$Poolable)
> at org.apache.xmlrpc.util.ThreadPool$Poolable.access$000(Unknown Source)
> at org.apache.xmlrpc.util.ThreadPool$Poolable$1.run(Unknown Source)
> - locked <0xbd2ed340> (a org.apache.xmlrpc.util.ThreadPool$Poolable$1)
> Found 1 deadlock.
> ----------
> And another slight variant on the above, from a debug build of revision
> 769436.
> ----------
> Found one Java-level deadlock:
> =============================
> "XML-RPC-6":
> waiting to lock monitor 0x0870d8ec (object 0xbac020f8, a
> org.apache.xmlrpc.util.ThreadPool),
> which is held by "XML-RPC Weblistener"
> "XML-RPC Weblistener":
> waiting to lock monitor 0x0814de4c (object 0xbad73820, a
> org.apache.xmlrpc.util.ThreadPool$Poolable$1),
> which is held by "XML-RPC-5"
> "XML-RPC-5":
> waiting to lock monitor 0x0814eacc (object 0xbad73b48, a
> org.apache.xmlrpc.util.ThreadPool$Poolable),
> which is held by "XML-RPC Weblistener"
> Java stack information for the threads listed above:
> ===================================================
> "XML-RPC-6":
> at org.apache.xmlrpc.util.ThreadPool.repool(ThreadPool.java:136)
> - waiting to lock <0xbac020f8> (a org.apache.xmlrpc.util.ThreadPool)
> at org.apache.xmlrpc.util.ThreadPool$Poolable$1.run(ThreadPool.java:70)
> "XML-RPC Weblistener":
> at org.apache.xmlrpc.util.ThreadPool$Poolable.start(ThreadPool.java:106)
> - waiting to lock <0xbad73820> (a
> org.apache.xmlrpc.util.ThreadPool$Poolable$1)
> - locked <0xbad73b48> (a org.apache.xmlrpc.util.ThreadPool$Poolable)
> at org.apache.xmlrpc.util.ThreadPool.startTask(ThreadPool.java:168)
> - locked <0xbac020f8> (a org.apache.xmlrpc.util.ThreadPool)
> at org.apache.xmlrpc.webserver.WebServer.run(WebServer.java:338)
> at java.lang.Thread.run(Thread.java:619)
> "XML-RPC-5":
> at
> org.apache.xmlrpc.util.ThreadPool$Poolable.getTask(ThreadPool.java:99)
> - waiting to lock <0xbad73b48> (a
> org.apache.xmlrpc.util.ThreadPool$Poolable)
> at
> org.apache.xmlrpc.util.ThreadPool$Poolable.access$100(ThreadPool.java:47)
> at org.apache.xmlrpc.util.ThreadPool$Poolable$1.run(ThreadPool.java:59)
> - locked <0xbad73820> (a org.apache.xmlrpc.util.ThreadPool$Poolable$1)
> Found 1 deadlock.
> ----------
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