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Posted to issues@hbase.apache.org by "stack (Commented) (JIRA)" <ji...@apache.org> on 2012/01/13 23:00:40 UTC

[jira] [Commented] (HBASE-5190) Limit the IPC queue size based on calls' payload size

    [ https://issues.apache.org/jira/browse/HBASE-5190?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13185898#comment-13185898 ] 

stack commented on HBASE-5190:
------------------------------

Talking w/ J-D on backchannel, #2 is bad (blocking is what we currently do too so its bad toooooo).

If we block, its likely client can timeout.  If it times out, it will redo the request adding a new payload to the serverside ipc queue.  Now queue has same load twice (bad if ICV).   Server doesn't know client timed out till it goes to reply and the client is no longer there so it can double-count or double enter value.
                
> Limit the IPC queue size based on calls' payload size
> -----------------------------------------------------
>
>                 Key: HBASE-5190
>                 URL: https://issues.apache.org/jira/browse/HBASE-5190
>             Project: HBase
>          Issue Type: Improvement
>    Affects Versions: 0.90.5
>            Reporter: Jean-Daniel Cryans
>             Fix For: 0.94.0
>
>
> Currently we limit the number of calls in the IPC queue only on their count. It used to be really high and was dropped down recently to num_handlers * 10 (so 100 by default) because it was easy to OOME yourself when huge calls were being queued. It's still possible to hit this problem if you use really big values and/or a lot of handlers, so the idea is that we should take into account the payload size. I can see 3 solutions:
>  - Do the accounting outside of the queue itself for all calls coming in and out and when a call doesn't fit, throw a retryable exception.
>  - Same accounting but instead block the call when it comes in until space is made available.
>  - Add a new parameter for the maximum size (in bytes) of a Call and then set the size the IPC queue (in terms of the number of items) so that it could only contain as many items as some predefined maximum size (in bytes) for the whole queue.

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