[JAMES-253] deadlock in mordred connection pool

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.1.3
• Fix Version/s: 2.2.0
• Component/s: MailStore & MailRepository, SpoolManager & Processors
• Environment: Linux 2.4.24 - glibc 2.2 - j2sdk 1.4.2
• Assignee: Unassigned
• Reporter: Marcus Labib
• Created: 13/Apr/04 16:58
• Updated: 05/Jun/04 19:35
• Resolved: 14/Apr/04 16:41

Description

Hi,

since some time we are experiencing a deadlock in the mordred connection pool. It seems that this deadlock occurs only when sql queries take very long.

I submitted a patch to the james developer mailing list.

excerpt from a typical thread dump:

Found one Java-level deadlock:
=============================
"default Worker #4":
waiting to lock monitor 0x8856f1c (object 0x44b4d568, a org.apache.james.util.mordred.PoolConnEntry),
which is held by "Thread-3"
"Thread-3":
waiting to lock monitor 0x8856ffc (object 0x44b40138, a java.util.Vector),
which is held by "default Worker #4"

Java stack information for the threads listed above: ===================================================
"default Worker #4":
at
org.apache.james.util.mordred.PoolConnEntry.lock(PoolConnEntry.java:110)

• waiting to lock <0x44b4d568> (a
  org.apache.james.util.mordred.PoolConnEntry)
  at org.apache.james.util.mordred.JdbcDataSource.getConnection(JdbcDataSource.ja
  va:178)
• locked <0x44b40138> (a java.util.Vector)
  at org.apache.james.mailrepository.JDBCSpoolRepository.loadPendingMessages(JDBC
  SpoolRepository.java:281)
• locked <0x44b5f218> (a java.util.LinkedList)
  at org.apache.james.mailrepository.JDBCSpoolRepository.getNextPendingMessage(JD
  BCSpoolRepository.java:256)
• locked <0x44b5f218> (a java.util.LinkedList)
  at org.apache.james.mailrepository.JDBCSpoolRepository.accept(JDBCSpoolReposito
  ry.java:154)
  at
  org.apache.james.transport.JamesSpoolManager.run(JamesSpoolManager.java:350)
  at org.apache.avalon.excalibur.thread.impl.ExecutableRunnable.execute(Executabl
  eRunnable.java:47)
  at org.apache.avalon.excalibur.thread.impl.WorkerThread.run(WorkerThread.java:8
  0)
• locked <0x44ba24b0> (a
  org.apache.avalon.excalibur.thread.impl.WorkerThread)
  "Thread-3":
  at java.util.Vector.removeElement(Vector.java:605)
• waiting to lock <0x44b40138> (a java.util.Vector)
  at org.apache.james.util.mordred.JdbcDataSource.finalizeEntry(JdbcDataSource.ja
  va:579)
• locked <0x44b400b0> (a
  org.apache.james.util.mordred.JdbcDataSource)
  at
  org.apache.james.util.mordred.JdbcDataSource.run(JdbcDataSource.java:452)
• locked <0x44b4d568> (a
  org.apache.james.util.mordred.PoolConnEntry)
  at java.lang.Thread.run(Thread.java:536)