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https://issues.apache.org/jira/browse/SOLR-5215?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13762138#comment-13762138
]
ASF subversion and git services commented on SOLR-5215:
-------------------------------------------------------
Commit 1521236 from [~markrmil...@gmail.com] in branch 'dev/trunk'
[ https://svn.apache.org/r1521236 ]
SOLR-5215: Fix possibility of deadlock in ZooKeeper ConnectionManager.
> Deadlock in Solr Cloud ConnectionManager
> ----------------------------------------
>
> Key: SOLR-5215
> URL: https://issues.apache.org/jira/browse/SOLR-5215
> Project: Solr
> Issue Type: Bug
> Components: clients - java, SolrCloud
> Affects Versions: 4.2.1
> Environment: Linux 2.6.18-164.el5 #1 SMP Tue Aug 18 15:51:48 EDT 2009
> x86_64 x86_64 x86_64 GNU/Linux
> java version "1.6.0_18"
> Java(TM) SE Runtime Environment (build 1.6.0_18-b07)
> Java HotSpot(TM) 64-Bit Server VM (build 16.0-b13, mixed mode)
> Reporter: Ricardo Merizalde
> Assignee: Mark Miller
> Fix For: 4.5, 5.0
>
> Attachments: SOLR-5215.patch
>
>
> We are constantly seeing a deadlocks in our production application servers.
> The problem seems to be that a thread A:
> - tries to process an event and acquires the ConnectionManager lock
> - the update callback acquires connectionUpdateLock and invokes
> waitForConnected
> - waitForConnected tries to acquire the ConnectionManager lock (which already
> has)
> - waitForConnected calls wait and release the ConnectionManager lock (but
> still has the connectionUpdateLock)
> The a thread B:
> - tries to process an event and acquires the ConnectionManager lock
> - the update call back tries to acquire connectionUpdateLock but gets blocked
> holding the ConnectionManager lock and preventing thread A from getting out
> of the wait state.
>
> Here is part of the thread dump:
> "http-0.0.0.0-8080-82-EventThread" daemon prio=10 tid=0x0000000059965800
> nid=0x3e81 waiting for monitor entry [0x0000000057169000]
> java.lang.Thread.State: BLOCKED (on object monitor)
> at
> org.apache.solr.common.cloud.ConnectionManager.process(ConnectionManager.java:71)
> - waiting to lock <0x00002aab1b0e0ce0> (a
> org.apache.solr.common.cloud.ConnectionManager)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:519)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:495)
>
> "http-0.0.0.0-8080-82-EventThread" daemon prio=10 tid=0x000000005ad40000
> nid=0x3e67 waiting for monitor entry [0x000000004dbd4000]
> java.lang.Thread.State: BLOCKED (on object monitor)
> at
> org.apache.solr.common.cloud.ConnectionManager$1.update(ConnectionManager.java:98)
> - waiting to lock <0x00002aab1b0e0f78> (a java.lang.Object)
> at
> org.apache.solr.common.cloud.DefaultConnectionStrategy.reconnect(DefaultConnectionStrategy.java:46)
> at
> org.apache.solr.common.cloud.ConnectionManager.process(ConnectionManager.java:91)
> - locked <0x00002aab1b0e0ce0> (a
> org.apache.solr.common.cloud.ConnectionManager)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:519)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:495)
>
> "http-0.0.0.0-8080-82-EventThread" daemon prio=10 tid=0x00002aac4c2f7000
> nid=0x3d9a waiting for monitor entry [0x0000000042821000]
> java.lang.Thread.State: BLOCKED (on object monitor)
> at java.lang.Object.wait(Native Method)
> - waiting on <0x00002aab1b0e0ce0> (a
> org.apache.solr.common.cloud.ConnectionManager)
> at
> org.apache.solr.common.cloud.ConnectionManager.waitForConnected(ConnectionManager.java:165)
> - locked <0x00002aab1b0e0ce0> (a
> org.apache.solr.common.cloud.ConnectionManager)
> at
> org.apache.solr.common.cloud.ConnectionManager$1.update(ConnectionManager.java:98)
> - locked <0x00002aab1b0e0f78> (a java.lang.Object)
> at
> org.apache.solr.common.cloud.DefaultConnectionStrategy.reconnect(DefaultConnectionStrategy.java:46)
> at
> org.apache.solr.common.cloud.ConnectionManager.process(ConnectionManager.java:91)
> - locked <0x00002aab1b0e0ce0> (a
> org.apache.solr.common.cloud.ConnectionManager)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:519)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:495)
>
> Found one Java-level deadlock:
> =============================
> "http-0.0.0.0-8080-82-EventThread":
> waiting to lock monitor 0x000000005c7694b0 (object 0x00002aab1b0e0ce0, a
> org.apache.solr.common.cloud.ConnectionManager),
> which is held by "http-0.0.0.0-8080-82-EventThread"
> "http-0.0.0.0-8080-82-EventThread":
> waiting to lock monitor 0x00002aac4c314978 (object 0x00002aab1b0e0f78, a
> java.lang.Object),
> which is held by "http-0.0.0.0-8080-82-EventThread"
> "http-0.0.0.0-8080-82-EventThread":
> waiting to lock monitor 0x000000005c7694b0 (object 0x00002aab1b0e0ce0, a
> org.apache.solr.common.cloud.ConnectionManager),
> which is held by "http-0.0.0.0-8080-82-EventThread"
>
>
> Java stack information for the threads listed above:
> ===================================================
> "http-0.0.0.0-8080-82-EventThread":
> at
> org.apache.solr.common.cloud.ConnectionManager.process(ConnectionManager.java:71)
> - waiting to lock <0x00002aab1b0e0ce0> (a
> org.apache.solr.common.cloud.ConnectionManager)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:519)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:495)
> "http-0.0.0.0-8080-82-EventThread":
> at
> org.apache.solr.common.cloud.ConnectionManager$1.update(ConnectionManager.java:98)
> - waiting to lock <0x00002aab1b0e0f78> (a java.lang.Object)
> at
> org.apache.solr.common.cloud.DefaultConnectionStrategy.reconnect(DefaultConnectionStrategy.java:46)
> at
> org.apache.solr.common.cloud.ConnectionManager.process(ConnectionManager.java:91)
> - locked <0x00002aab1b0e0ce0> (a
> org.apache.solr.common.cloud.ConnectionManager)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:519)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:495)
> "http-0.0.0.0-8080-82-EventThread":
> at java.lang.Object.wait(Native Method)
> - waiting on <0x00002aab1b0e0ce0> (a
> org.apache.solr.common.cloud.ConnectionManager)
> at
> org.apache.solr.common.cloud.ConnectionManager.waitForConnected(ConnectionManager.java:165)
> - locked <0x00002aab1b0e0ce0> (a
> org.apache.solr.common.cloud.ConnectionManager)
> at
> org.apache.solr.common.cloud.ConnectionManager$1.update(ConnectionManager.java:98)
> - locked <0x00002aab1b0e0f78> (a java.lang.Object)
> at
> org.apache.solr.common.cloud.DefaultConnectionStrategy.reconnect(DefaultConnectionStrategy.java:46)
> at
> org.apache.solr.common.cloud.ConnectionManager.process(ConnectionManager.java:91)
> - locked <0x00002aab1b0e0ce0> (a
> org.apache.solr.common.cloud.ConnectionManager)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:519)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:495)
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