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Bug 236773 - OutOfMemoryError: Java heap space
Summary: OutOfMemoryError: Java heap space
Alias: None
Product: platform
Classification: Unclassified
Component: Filesystems (show other bugs)
Version: 7.4
Hardware: All All
: P3 normal (vote)
Assignee: Jaroslav Havlin
: 239299 239541 241051 245387 (view as bug list)
Depends on:
Reported: 2013-10-04 16:49 UTC by Jesse Glick
Modified: 2014-07-07 11:19 UTC (History)
4 users (show)

See Also:
Issue Type: DEFECT
Exception Reporter: 204372

stacktrace (400 bytes, text/plain)
2013-10-04 16:49 UTC, Jesse Glick

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Description Jesse Glick 2013-10-04 16:49:16 UTC
Build: NetBeans IDE Dev (Build 20131003-e1bc80c284d0)
VM: Java HotSpot(TM) Client VM, 24.0-b56, Java(TM) SE Runtime Environment, 1.7.0_40-b43
OS: Linux

User Comments:
jglick: Doing some complex Git magic on command line, forgot I had left project open in IDE, froze.

java.lang.OutOfMemoryError: Java heap space
   at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.addConditionWaiter(
   at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(
Comment 1 Jesse Glick 2013-10-04 16:49:17 UTC
Created attachment 140811 [details]
Comment 2 Marian Mirilovic 2013-10-15 11:32:28 UTC
From the exception ... there is nothing we can do about it ;(
Comment 3 Tomas Hurka 2013-11-21 09:51:12 UTC
Size of the queue org.openide.filesystems.FCLSUpport.q is over 19 millions (!). This huge size caused the OOME. The thread dump shows that "Async FileEvent dispatcher" thread responsible for removing items from the queue is blocked. This can explain why the size of the queue is so huge. It should be investigated, why "Async FileEvent dispatcher" thread is blocked and if there is a way not to block it for a long period of time. Reassigning to filesystems for further investigation.
Comment 4 Jaroslav Havlin 2013-11-22 15:10:32 UTC
Jesse, what type of magic did you do? Is it possible that it caused 19 million file changes? (I guess it isn't.)
If you were working with some open source project, can you please provide link to the repository?
(I'm not able to reproduce the bug with Mercurial and NetBeans sources, size of FCLSUpport.q hardly reaches 1000 items).
Thank you.
Comment 5 Jesse Glick 2013-11-22 15:35:53 UTC
This was several weeks ago so I cannot remember exactly what I was doing at the time (probably some git-mv operations, maybe git-checkout etc.), but from the log file it looks like I was working on Jenkins core, which is sort of big but not that big (currently ~11k files).
Comment 6 Jaroslav Havlin 2013-11-27 14:39:27 UTC
I was able to reproduce the bug with the Jenkins Core sources.
Shortly after invoking "git mv src src2", size of FCLSupport.q was 1.3 million items.
The main problem was creation of DispatchEventWrapper for each pair of FileEvent and filesystem-level FileChangeListener.
I created a DispatchEventWrapper that can hold a list of listeners instead of a single listener. The good thing is that a list of listeners can be shared by multiple wrappers.
After this change, the size of the queue reached only 22,000 items (1.7% of the original size).

Thank you, Jesse, for reporting and your comments, and Tomas for help with evaluation.
Comment 7 Quality Engineering 2013-11-29 02:54:26 UTC
Integrated into 'main-silver', will be available in build *201311290002* on (upload may still be in progress)

User: Jaroslav Havlin <>
Log: #236773: Out of memory - Too many items in FCLSupport.q
Comment 8 Jaroslav Havlin 2013-12-10 12:46:27 UTC
*** Bug 239299 has been marked as a duplicate of this bug. ***
Comment 9 Jaroslav Havlin 2013-12-17 07:50:34 UTC
*** Bug 239541 has been marked as a duplicate of this bug. ***
Comment 10 Jaroslav Havlin 2014-01-28 11:43:34 UTC
*** Bug 241051 has been marked as a duplicate of this bug. ***
Comment 11 Jaroslav Havlin 2014-07-07 11:19:12 UTC
*** Bug 245387 has been marked as a duplicate of this bug. ***