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Posted to issues@hbase.apache.org by "stack (JIRA)" <ji...@apache.org> on 2011/01/31 21:26:29 UTC
[jira] Assigned: (HBASE-3493) HMaster sometimes hangs during
initialization due to missing notify call
[ https://issues.apache.org/jira/browse/HBASE-3493?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
stack reassigned HBASE-3493:
----------------------------
Assignee: Bruno Dumon
> HMaster sometimes hangs during initialization due to missing notify call
> ------------------------------------------------------------------------
>
> Key: HBASE-3493
> URL: https://issues.apache.org/jira/browse/HBASE-3493
> Project: HBase
> Issue Type: Bug
> Components: master
> Affects Versions: 0.90.0
> Environment: Linux, HBase 0.90
> Reporter: Bruno Dumon
> Assignee: Bruno Dumon
> Attachments: assignment-manager-regions-notify-patch.txt
>
>
> During HMaster.finishInitialization(), assignRootAndMeta() is called, which at some point does:
> {code}
> this.assignmentManager.waitForAssignment(HRegionInfo.FIRST_META_REGIONINFO);
> {code}
> And waitForAssignment does this:
> {code}
> synchronized(regions) {
> while(!regions.containsKey(regionInfo)) {
> regions.wait();
> }
> }
> {code}
> However, I could not find any call to regions.notify(), so this could wait forever.
> I have not noticed this problem on a real cluster, only when using HBaseTestingUtility on a slow and low-memory Hudson server (I can reproduce it on my local machine by creating some background load). Adding a notify() call when regions.put() is called seems to fix the problem. Will attach patch.
> For reference, this was based on seeing the following from jstack:
> {noformat}
> "Master:0;lat:44776" prio=10 tid=0x08d5b400 nid=0x381a in Object.wait() [0x9c76d000]
> java.lang.Thread.State: WAITING (on object monitor)
> at java.lang.Object.wait(Native Method)
> - waiting on <0xa5196fb8> (a java.util.TreeMap)
> at java.lang.Object.wait(Object.java:485)
> at org.apache.hadoop.hbase.master.AssignmentManager.waitForAssignment(AssignmentManager.java:1152)
> - locked <0xa5196fb8> (a java.util.TreeMap)
> at org.apache.hadoop.hbase.master.HMaster.assignRootAndMeta(HMaster.java:440)
> at org.apache.hadoop.hbase.master.HMaster.finishInitialization(HMaster.java:382)
> at org.apache.hadoop.hbase.master.HMaster.run(HMaster.java:277)
> at java.lang.Thread.run(Thread.java:619)
> {noformat}
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