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https://issues.apache.org/jira/browse/HBASE-3323?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12972370#action_12972370
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stack commented on HBASE-3323:
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Ok. I've overwritten the logs from above. I've tested more since and haven't
run into the issue. Will keep at it. Will open new issue if I run into it.
I'd say go ahead still w/ commit of this.
> OOME in master splitting logs
> -----------------------------
>
> Key: HBASE-3323
> URL: https://issues.apache.org/jira/browse/HBASE-3323
> Project: HBase
> Issue Type: Bug
> Components: master
> Affects Versions: 0.90.0
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Blocker
> Fix For: 0.90.0
>
> Attachments: hbase-3323.4.txt, hbase-3323.5.txt, hbase-3323.txt,
> hbase-3323.txt, hbase-3323.txt, sizes.png
>
>
> In testing a RS failure under heavy increment workload I ran into an OOME
> when the master was splitting the logs.
> In this test case, I have exactly 136 bytes per log entry in all the logs,
> and the logs are all around 66-74MB). With a batch size of 3 logs, this means
> the master is loading about 500K-600K edits per log file. Each edit ends up
> creating 3 byte[] objects, the references for which are each 8 bytes of RAM,
> so we have 160 (136+8*3) bytes per edit used by the byte[]. For each edit we
> also allocate a bunch of other objects: one HLog$Entry, one WALEdit, one
> ArrayList, one LinkedList$Entry, one HLogKey, and one KeyValue. Overall this
> works out to 400 bytes of overhead per edit. So, with the default settings on
> this fairly average workload, the 1.5M log entries takes about 770MB of RAM.
> Since I had a few log files that were a bit larger (around 90MB) it exceeded
> 1GB of RAM and I got an OOME.
> For one, the 400 bytes per edit overhead is pretty bad, and we could probably
> be a lot more efficient. For two, we should actually account this rather than
> simply having a configurable "batch size" in the master.
> I think this is a blocker because I'm running with fairly default configs
> here and just killing one RS made the cluster fall over due to master OOME.
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