[jira] Commented: (HBASE-1177) Delay when client is located on the same node as the regionserver

["Jean-Daniel Cryans (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-1177?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12670004#action_12670004 ] 

Jean-Daniel Cryans commented on HBASE-1177:
-------------------------------------------

On my rig:

{code}
jdcryans@jdcryans-lasi:~/svn/hbase/trunk$ ./bin/hbase ReadDelayTest
09/02/03 11:22:36 INFO zookeeper.ZooKeeperWrapper: Quorum servers: localhost:2181
09/02/03 11:22:42 INFO client.HBaseAdmin: Enabled table test_table
Read 1 row with 7 columns 100 times in 78ms
Read 1 row with 8 columns 100 times in 4000ms
{code}

> Delay when client is located on the same node as the regionserver
> -----------------------------------------------------------------
>
>                 Key: HBASE-1177
>                 URL: https://issues.apache.org/jira/browse/HBASE-1177
>             Project: Hadoop HBase
>          Issue Type: Bug
>    Affects Versions: 0.19.0
>         Environment: Linux 2.6.25 x86_64
>            Reporter: Jonathan Gray
>            Priority: Blocker
>             Fix For: 0.20.0
>
>         Attachments: ReadDelayTest.java
>
>
> During testing of HBASE-80, we uncovered a strange 40ms delay for random reads.  We ran a series of tests and found that it only happens when the client is on the same node as the RS and for a certain range of payloads (not specifically related to number of columns or size of them, only total payload).  It appears to be precisely 40ms every time.
> Unsure if this is particular to our architecture, but it does happen on all nodes we've tried.  Issue completely goes away with very large payloads or moving the client.
> Will post a test program tomorrow if anyone can test on a different architecture.
> Making a blocker for 0.20.  Since this happens when you have an MR task running local to the RS, and this is what we try to do, might also consider making this a blocker for 0.19.1.

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