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https://issues.apache.org/jira/browse/HBASE-1177?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Gray updated HBASE-1177:
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Attachment: screenshot-3.jpg
Here is a graph I made at the same time I originally filed this issue.
What it shows are very explicit ranges of payloads for which an enormous and
fixed delay occurs, and then goes away as the row returned gets larger.
I'm trying to match up this behavior with what you're plotting, Jim. Can you
explain further what the axis are on yours?
> 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
> Assignee: Jim Kellerman
> Priority: Blocker
> Fix For: 0.20.0
>
> Attachments: ReadDelayTest.java, screenshot-1.jpg, screenshot-2.jpg,
> screenshot-3.jpg
>
>
> 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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