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Posted to issues@hbase.apache.org by "stack (JIRA)" <ji...@apache.org> on 2016/02/18 23:23:18 UTC

[jira] [Resolved] (HBASE-24) Scaling: Too many open file handles to datanodes

     [ https://issues.apache.org/jira/browse/HBASE-24?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

stack resolved HBASE-24.
------------------------
    Resolution: Won't Fix

Resolving as 'wont fix'... We open lots of files. Would be good if we opened less.

> Scaling: Too many open file handles to datanodes
> ------------------------------------------------
>
>                 Key: HBASE-24
>                 URL: https://issues.apache.org/jira/browse/HBASE-24
>             Project: HBase
>          Issue Type: Bug
>          Components: regionserver
>            Reporter: stack
>            Priority: Blocker
>         Attachments: HBASE-823.patch, MonitoredReader.java
>
>
> We've been here before (HADOOP-2341).
> Today the rapleaf gave me an lsof listing from a regionserver.  Had thousands of open sockets to datanodes all in ESTABLISHED and CLOSE_WAIT state.  On average they seem to have about ten file descriptors/sockets open per region (They have 3 column families IIRC.  Per family, can have between 1-5 or so mapfiles open per family -- 3 is max... but compacting we open a new one, etc.).
> They have thousands of regions.   400 regions -- ~100G, which is not that much -- takes about 4k open file handles.
> If they want a regionserver to server a decent disk worths -- 300-400G -- then thats maybe 1600 regions... 16k file handles.  If more than just 3 column families..... then we are in danger of blowing out limits if they are 32k.
> We've been here before with HADOOP-2341.
> A dfsclient that used non-blocking i/o would help applications like hbase (The datanode doesn't have this problem as bad -- CLOSE_WAIT on regionserver side, the bulk of the open fds in the rapleaf log, don't have a corresponding open resource on datanode end).
> Could also just open mapfiles as needed, but that'd kill our random read performance and its bad enough already.



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