FAQ
Hi,

We are using CDH 4.3 with Cloudera Manager 4.6.1. We've setup our HBase
cluster giving plenty of RAM to RegionServer, that is setting *Java Heap
Size of HBase RegionServer in Bytes* to 6 GiB. First performance tests
showed really bad results, which we narrowed down to GC problems: the minor
collection was called 10 times a second! Further investigations showed us
that the size of Eden Space was just 6 MiB, which we think can be due to
the reason Tenured Space doesn't grow fast enough from the initial settings.

The good practice for Java long-time running server process is to set *Xms*equal to
*Xmx* to get rid of pauses for resizing, have you considered that?

Regards,
Alex

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  • Philip Zeyliger at Jul 25, 2013 at 5:36 pm
    Hi Alexia,

    You're right--we should be setting it. There's an internal bug tracking
    it--we just haven't fixed it yet.

    In the meantime, you can work around it with putting the relevant flag in
    the "java options safety valve."

    Thanks

    -- Philip

    On Thu, Jul 25, 2013 at 1:07 AM, Alexei Shpikat wrote:

    Hi,

    We are using CDH 4.3 with Cloudera Manager 4.6.1. We've setup our HBase
    cluster giving plenty of RAM to RegionServer, that is setting *Java Heap
    Size of HBase RegionServer in Bytes* to 6 GiB. First performance tests
    showed really bad results, which we narrowed down to GC problems: the minor
    collection was called 10 times a second! Further investigations showed us
    that the size of Eden Space was just 6 MiB, which we think can be due to
    the reason Tenured Space doesn't grow fast enough from the initial settings.

    The good practice for Java long-time running server process is to set *Xms
    * equal to *Xmx* to get rid of pauses for resizing, have you considered
    that?

    Regards,
    Alex
  • Alexei Shpikat at Jul 26, 2013 at 10:45 am
    Hi Philip,

    Yes, that's what we did, just wanted to make you know about the situation
    like this, as it's not quite obvious. Actually, we were lucky to run into
    this issue at such scale (I mean 6 MiB), if it were something larger it
    could have silently waited for a while before crashing.
    On Thursday, July 25, 2013 8:35:44 PM UTC+3, Philip Zeyliger wrote:

    Hi Alexia,

    You're right--we should be setting it. There's an internal bug tracking
    it--we just haven't fixed it yet.

    In the meantime, you can work around it with putting the relevant flag in
    the "java options safety valve."

    Thanks

    -- Philip


    On Thu, Jul 25, 2013 at 1:07 AM, Alexei Shpikat <a.sh...@gmail.com<javascript:>
    wrote:
    Hi,

    We are using CDH 4.3 with Cloudera Manager 4.6.1. We've setup our HBase
    cluster giving plenty of RAM to RegionServer, that is setting *Java Heap
    Size of HBase RegionServer in Bytes* to 6 GiB. First performance tests
    showed really bad results, which we narrowed down to GC problems: the minor
    collection was called 10 times a second! Further investigations showed us
    that the size of Eden Space was just 6 MiB, which we think can be due to
    the reason Tenured Space doesn't grow fast enough from the initial settings.

    The good practice for Java long-time running server process is to set *
    Xms* equal to *Xmx* to get rid of pauses for resizing, have you
    considered that?

    Regards,
    Alex

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postedJul 25, '13 at 8:07a
activeJul 26, '13 at 10:45a
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Alexei Shpikat: 2 posts Philip Zeyliger: 1 post

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