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From "Thejas M Nair (JIRA)" <j...@apache.org>
Subject [jira] Commented: (PIG-1466) Improve log messages for memory usage
Date Fri, 13 Aug 2010 00:26:17 GMT

    [ https://issues.apache.org/jira/browse/PIG-1466?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12898020#action_12898020
] 

Thejas M Nair commented on PIG-1466:
------------------------------------

I am planning to change as following -
1. Change the string "low memory handler called" to "cleaner notified" .
2. Print additional log message stating total spill object memory freed and total number of
objects freed. This will be printed the first time a candidate to be freed is found, and then
every 10 times the GC is called from the code. (GC is called after a threshold of memory suitable
to be freed has been collected.)



> Improve log messages for memory usage
> -------------------------------------
>
>                 Key: PIG-1466
>                 URL: https://issues.apache.org/jira/browse/PIG-1466
>             Project: Pig
>          Issue Type: Improvement
>          Components: impl
>    Affects Versions: 0.7.0
>            Reporter: Ashutosh Chauhan
>            Assignee: Thejas M Nair
>            Priority: Minor
>             Fix For: 0.8.0
>
>
> For anything more then a moderately sized dataset Pig usually spits following messages:
> {code}
> 2010-05-27 18:28:31,659 INFO org.apache.pig.impl.util.SpillableMemoryManager: low memory
handler called (Usage
> threshold exceeded) init = 4194304(4096K) used = 672012960(656262K) committed = 954466304(932096K)
max =
> 954466304(932096K)
> 2010-05-27 18:10:52,653 INFO org.apache.pig.impl.util.SpillableMemoryManager: low memory
handler called (Collection
> threshold exceeded) init = 4194304(4096K) used = 954466304(932096K) committed = 954466304(932096K)
max =
> 954466304(932096K)
> {code}
> This seems to confuse users a lot. Once these messages are printed, users tend to believe
that Pig is having hard time with memory, is spilling to disk etc. but in fact Pig might be
cruising along at ease. We should be little more careful what to print in logs. Currently
these are printed when a notification is sent by JVM and some other conditions are met which
may not necessarily indicate low memory condition. Furthermore, with {{InternalCachedBag}}
embraced everywhere in favor of {{DefaultBag}}, these messages have lost their usefulness.
At the every least, we should lower the log level at which these are printed. 

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