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Koji Noguchi commented on PIG-3148: ----------------------------------- Rohini asked me to clarify why I'm adding extra param instead of simply calling gc() at the top of handleNotification(). Reason I added extra param is, * When I tried just adding gc() at the top, suddenly I saw all of my mappers stuck, spending 99% of cputime on gc. I then learned that handleNotification is called much more frequently than I first anticipated when the application is using more than the threshold and have nothing much to spill. That convinced me to add more condition to reduce the gc() calls. * Motivation of my patch here is to avoid OutOfMemory when application is holding a reference to a large stale bag while spilling unnecessarily. For that, bag being spilled has to be proportional to the heap size of the application to cause OOM. > OutOfMemory exception while spilling stale DefaultDataBag. Extra option to > gc() before spilling large bag. > ---------------------------------------------------------------------------------------------------------- > > Key: PIG-3148 > URL: https://issues.apache.org/jira/browse/PIG-3148 > Project: Pig > Issue Type: Improvement > Components: impl > Reporter: Koji Noguchi > Assignee: Koji Noguchi > Attachments: pig-3148-v01.patch > > > Our user reported that one of their jobs in pig 0.10 occasionally failed with > 'Error: GC overhead limit exceeded' or 'Error: Java heap space', but > rerunning it sometimes finishes successfully. > For 1G heap reducer, heap dump showed it contained two huge DefaultDataBag > with 300-400MBytes each when failing with OOM. > Jstack at the time of OOM always showed that spill was running. > {noformat} > "Low Memory Detector" daemon prio=10 tid=0xb9c11800 nid=0xa52 runnable > [0xb9afc000] > java.lang.Thread.State: RUNNABLE > at java.io.FileOutputStream.writeBytes(Native Method) > at java.io.FileOutputStream.write(FileOutputStream.java:260) > at > java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65) > at java.io.BufferedOutputStream.write(BufferedOutputStream.java:109) > - locked <0xe57c6390> (a java.io.BufferedOutputStream) > at java.io.DataOutputStream.write(DataOutputStream.java:90) > - locked <0xe57c60b8> (a java.io.DataOutputStream) > at java.io.FilterOutputStream.write(FilterOutputStream.java:80) > at org.apache.pig.data.utils.SedesHelper.writeBytes(SedesHelper.java:46) > at org.apache.pig.data.BinInterSedes.writeDatum(BinInterSedes.java:537) > at org.apache.pig.data.BinInterSedes.writeDatum(BinInterSedes.java:435) > at > org.apache.pig.data.utils.SedesHelper.writeGenericTuple(SedesHelper.java:135) > at org.apache.pig.data.BinInterSedes.writeTuple(BinInterSedes.java:613) > at org.apache.pig.data.BinInterSedes.writeDatum(BinInterSedes.java:443) > at org.apache.pig.data.DefaultDataBag.spill(DefaultDataBag.java:106) > - locked <0xceb16190> (a java.util.ArrayList) > at > org.apache.pig.impl.util.SpillableMemoryManager.handleNotification(SpillableMemoryManager.java:243) > - locked <0xbeb86318> (a java.util.LinkedList) > at > sun.management.NotificationEmitterSupport.sendNotification(NotificationEmitterSupport.java:138) > at sun.management.MemoryImpl.createNotification(MemoryImpl.java:171) > at > sun.management.MemoryPoolImpl$PoolSensor.triggerAction(MemoryPoolImpl.java:272) > at sun.management.Sensor.trigger(Sensor.java:120) > {noformat} -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira