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Posted to derby-dev@db.apache.org by "Brett Bergquist (JIRA)" <ji...@apache.org> on 2012/12/10 23:41:22 UTC
[jira] [Comment Edited] (DERBY-5632) Logical deadlock happened when
freezing/unfreezing the database
[ https://issues.apache.org/jira/browse/DERBY-5632?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13528381#comment-13528381 ]
Brett Bergquist edited comment on DERBY-5632 at 12/10/12 10:39 PM:
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This is still a major problem even when using the same connection, the database can get into a state that the freeze works, but the unfreeze locks up.
At a customer site, this procedure is done each night to backup the database. Since the 9/1/2012, this has failed 5 times, causing the database to remain in a frozen state with no possibility of unfreezing it. When in this state, no connections to the database can be created including a connection to shut down the database. Forcefully killing the network server is the only way to recover.
Note that there is a background job in the system that is running an UPDATE_STATISTICS every minute as in Derby 10.8.2.2, the automatic statistics update daemon has problems and cannot be used.
was (Author: bbergquist):
This is still a major problem even when using the same connection, the database can get into a state that the freeze works, but the unfreeze locks up.
At a customer size, this procedure is done each night to backup the database. Since the 9/1/2012, this has failed 5 times, causing the database to remain in a frozen state with no possibility of unfreezing it. When in this state, no connections to the database can be created including a connection to shut down the database. Forcefully killing the network server is the only way to recover.
Note that there is a background job in the system that is running an UPDATE_STATISTICS every minute as in Derby 10.8.2.2, the automatic statistics update daemon has problems and cannot be used.
> Logical deadlock happened when freezing/unfreezing the database
> ---------------------------------------------------------------
>
> Key: DERBY-5632
> URL: https://issues.apache.org/jira/browse/DERBY-5632
> Project: Derby
> Issue Type: Bug
> Components: Documentation, Services
> Affects Versions: 10.8.2.2
> Environment: Oracle M3000/Solaris 10
> Reporter: Brett Bergquist
> Labels: derby_triage10_10
> Attachments: stack.txt
>
>
> Tried to make a quick database backup by freezing the database, performing a ZFS snapshot, and then unfreezing the database. The database was frozen but then a connection to the database could not be established to unfreeze the database.
> Looking at the stack trace of the network server, , I see 3 threads that are trying to process a connection request. Each of these is waiting on:
> at org.apache.derby.impl.store.access.RAMAccessManager.conglomCacheFind(Unknown Source)
> - waiting to lock <0xfffffffd3a7fcc68> (a org.apache.derby.impl.services.cache.ConcurrentCache)
> That object is owned by:
> - locked <0xfffffffd3a7fcc68> (a org.apache.derby.impl.services.cache.ConcurrentCache)
> at org.apache.derby.impl.store.access.RAMTransaction.findExistingConglomerate(Unknown Source)
> at org.apache.derby.impl.store.access.RAMTransaction.openGroupFetchScan(Unknown Source)
> at org.apache.derby.impl.services.daemon.IndexStatisticsDaemonImpl.updateIndexStatsMinion(Unknown Source)
> at org.apache.derby.impl.services.daemon.IndexStatisticsDaemonImpl.runExplicitly(Unknown Source)
> at org.apache.derby.impl.sql.execute.AlterTableConstantAction.updateStatistics(Unknown Source)
> which itself is waiting for the object:
> at java.lang.Object.wait(Native Method)
> - waiting on <0xfffffffd3ac1d608> (a org.apache.derby.impl.store.raw.log.LogToFile)
> at java.lang.Object.wait(Object.java:485)
> at org.apache.derby.impl.store.raw.log.LogToFile.flush(Unknown Source)
> - locked <0xfffffffd3ac1d608> (a org.apache.derby.impl.store.raw.log.LogToFile)
> at org.apache.derby.impl.store.raw.log.LogToFile.flush(Unknown Source)
> at org.apache.derby.impl.store.raw.data.BaseDataFileFactory.flush(Unknown Source)
> So basically what I think is happening is that the database is frozen, the statistics are being updated on another thread which has the "org.apache.derby.impl.services.cache.ConcurrentCache" locked and then waits for the LogToFile lock and the connecting threads are waiting to lock "org.apache.derby.impl.services.cache.ConcurrentCache" to connect and these are where the database is going to be unfrozen. Not a deadlock as far as the JVM is concerned but it will never leave this state either.
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