[JCR-3226] stateCreated deadlock

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.2, 2.4
• Component/s: jackrabbit-core
• Labels: deadlock
• Assignee: Thomas Mueller
• Reporter: Jukka Zitting
• Created: 06/Feb/12 11:48
• Updated: 28/Jul/15 07:46

Description

In JCR-2650 a potential deadlock in SessionItemStateManager.stateModified() got fixed by postponing the work to the save() call.

Unfortunately this still leaves the stateCreated() method vulnerable to a similar (though much less likely) deadlock scenario (observed in Jackrabbit 2.2.x):

Thread A:
at org.apache.jackrabbit.core.state.NodeState.copy(NodeState.java:118)

• waiting to lock <0x00007ffec8ddfa18> (a org.apache.jackrabbit.core.state.NodeState)
• locked <0x00007ffec8ddf9d8> (a org.apache.jackrabbit.core.state.NodeState)
  at org.apache.jackrabbit.core.state.ItemState.pull(ItemState.java:152)
• locked <0x00007ffec8ddf9d8> (a org.apache.jackrabbit.core.state.NodeState)
  at org.apache.jackrabbit.core.state.SessionItemStateManager.stateCreated(SessionItemStateManager.java:791)
  at org.apache.jackrabbit.core.state.StateChangeDispatcher.notifyStateCreated(StateChangeDispatcher.java:94)
  at org.apache.jackrabbit.core.state.LocalItemStateManager.stateCreated(LocalItemStateManager.java:428)
  at org.apache.jackrabbit.core.state.StateChangeDispatcher.notifyStateCreated(StateChangeDispatcher.java:94)
  at org.apache.jackrabbit.core.state.SharedItemStateManager.stateCreated(SharedItemStateManager.java:398)
  at org.apache.jackrabbit.core.state.ItemState.notifyStateCreated(ItemState.java:231)
  at org.apache.jackrabbit.core.state.ChangeLog.persisted(ChangeLog.java:309)
  at org.apache.jackrabbit.core.state.SharedItemStateManager$Update.end(SharedItemStateManager.java:777)
  at org.apache.jackrabbit.core.state.SharedItemStateManager.update(SharedItemStateManager.java:1488)
  at org.apache.jackrabbit.core.state.LocalItemStateManager.update(LocalItemStateManager.java:351)
  at org.apache.jackrabbit.core.state.XAItemStateManager.update(XAItemStateManager.java:354)
  at org.apache.jackrabbit.core.state.LocalItemStateManager.update(LocalItemStateManager.java:326)
  at org.apache.jackrabbit.core.state.SessionItemStateManager.update(SessionItemStateManager.java:289)
  at org.apache.jackrabbit.core.ItemSaveOperation.perform(ItemSaveOperation.java:258)
  at org.apache.jackrabbit.core.session.SessionState.perform(SessionState.java:200)
  at org.apache.jackrabbit.core.ItemImpl.perform(ItemImpl.java:91)
  at org.apache.jackrabbit.core.ItemImpl.save(ItemImpl.java:329)

Thread B:
at org.apache.jackrabbit.core.state.NodeState.copy(NodeState.java:119)

• waiting to lock <0x00007ffec8ddf9d8> (a org.apache.jackrabbit.core.state.NodeState)
• locked <0x00007ffec8ddfa18> (a org.apache.jackrabbit.core.state.NodeState)
  at org.apache.jackrabbit.core.NodeImpl.makePersistent(NodeImpl.java:869)
• locked <0x00007ffec8ddfa18> (a org.apache.jackrabbit.core.state.NodeState)
  at org.apache.jackrabbit.core.ItemSaveOperation.persistTransientItems(ItemSaveOperation.java:836)
  at org.apache.jackrabbit.core.ItemSaveOperation.perform(ItemSaveOperation.java:243)
  at org.apache.jackrabbit.core.session.SessionState.perform(SessionState.java:200)
  at org.apache.jackrabbit.core.ItemImpl.perform(ItemImpl.java:91)
  at org.apache.jackrabbit.core.ItemImpl.save(ItemImpl.java:329)
  at org.apache.jackrabbit.core.session.SessionSaveOperation.perform(SessionSaveOperation.java:42)
  at org.apache.jackrabbit.core.session.SessionState.perform(SessionState.java:200)
  at org.apache.jackrabbit.core.SessionImpl.perform(SessionImpl.java:355)
  at org.apache.jackrabbit.core.SessionImpl.save(SessionImpl.java:758)

IIUC this can only occur when two sessions are concurrently importing a node with the same UUID.