[FLUME-1258] TailDirSource might get dead lock when delete file in dir.

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Won't Fix
• Affects Version/s: 0.9.3
• Fix Version/s: 0.9.5
• Component/s: Sinks+Sources
• Assignee: Unassigned
• Reporter: Li Junjun
• Created: 05/Jun/12 10:49
• Updated: 05/Nov/14 11:33
• Resolved: 05/Nov/14 11:33

Description

when fileDelete fired ,DirWatcher it calls tail.removeCursor(c)
DirWather:
1,(sucess)get lock of tail --> synchronized public void removeCursor
2,get lock of rmCursors--->synchronized (rmCursors)

{ rmCursors.add(cursor);}

if at this time , TailThread has some rmCursors to handle
TailThread:
1,(sucess)get lock of rmCursors
2,foreach rmCursors call c.flush()
in c.flush(), it put event in SynchronousQueue,block until
another thread(PumperThread) to poll it

PumperThread:
1,(success)poll from SynchronousQueue,
2,try get lock of tail to updateEventProcessingStats,but it can beacuse
DirWather get it!so the PumperThread block here.

Because the PumperThread blocked , the SynchronousQueue didn't release it's capacity,then the TailThread 2 step blocked ,and the TailThread didn't release the lock of rmCursors ,and the DirWather 2 step blocked .

it's a block chain.