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: Network Server
Affects Versions: 10.8.2.2
Environment: Oracle M3000/Solaris 10
Reporter: Brett Bergquist
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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