Resurrecting this topic with some clarity on the issue and it's remedy.   If RegionServers would be keeping dead connections to the Datanodes, the same symnptoms would be seen, many connection in CLOSE_WAIT, and file descriptor number increasing. In extreme cases the limit could be reached, whioch would case the host node to fail with no more open file descriptors to use issue.   There wasa bug in HBase prior to CDH5.13 which is described in this upstream JIRA in more detail[1]: HBASE-9393 Hbase does not closing a closed socket resulting in many CLOSE_WAIT]   This issue was patched in the following CDH releases: CDH5.13.0, CDH5.13.1, CDH5.13.2, CDH5.13.3, CDH5.14.0,  CDH5.14.2, CDH5.14.4, CDH5.15.0,  CDH5.15.1, CDH6.0.0.   [1] - upstream HBase JIRA - https://issues.apache.org/jira/browse/HBASE-9393?attachmentOrder=asc ... View more

@jakeri wrote: Hello,   We are also experiencing this. Could you point us to which patch this is?   Kind regards, Jakob The patch is part of CDH 5.1.4 and CDH 5.2.0 (and later versions). You can simply upgrade to v5.1.4 from v5.1.0 for the fix. If you have a support contract, you can log a case for a patch on a specific version of CDH. ... View more

............edited........   Hi all Thank you for help problem solved   Problem was caused by one node which was in maintenance mode(and was turned off). after I deleted this node from cluster problem solved. I don't know why occurred this problem because I was not marking this maintenance node when was adding impala service ... View more

Thank you rteague.  I think my problem has been resolved.  🙂 ... View more