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From "Rohini Palaniswamy (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PIG-4555) Add -XX:+UseNUMA for Tez jobs
Date Fri, 22 May 2015 22:57:18 GMT

    [ https://issues.apache.org/jira/browse/PIG-4555?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14556958#comment-14556958

Rohini Palaniswamy commented on PIG-4555:

bq. i end-up having my containers (the AM one) being killed because they use too much virtual
memory (about 17GB of virtual memory)
   17GB is really bad. How much was the Xmx? What is the virtual memory without NUMA?

bq. But for sure, in my case, setting -XX:+UseNUMA do trigger an OOM.
   Are you sure it hits OOM or just the container being killed because of yarn.nodemanager.vmem-pmem-ratio
being breached? 

bq. I'm pretty sure there is already some configuration variables one can set in its tez-site.xml
file to set this option so no need to have pig force this setting by code. For what i understand,
the real problem is not about -XX!:+UseNUMA. The real problem is more that some option from
the tez configuration are ignored.
   TEZ_AM_LAUNCH_CMD_OPTS_DEFAULT is "-XX:+PrintGCDetails -verbose:gc -XX:+PrintGCTimeStamps
-XX:+UseNUMA -XX:+UseParallelGC" . i.e  -XX:+UseNUMA is part of default tez AM options. In
Pig, we give preference to mapreduce AM settings (if tez.am.launch.cmd-opts is not overriden
in tez-site.xml) and translate them to tez instead of using the mentioned tez defaults. Since
the mapreduce AM settings are always there from mapred-default.xml or mapred-site.xml, -XX:+UseNUMA
is never there. So this is about making use of the default tez settings in Pig. If in a particular
environment  -XX:+UseNUMA is problematic, it can be overriden in tez-site.xml.

The real issue of why Tez AM performed poorly without NUMA is still there and will be tracked
in TEZ jira. You have some concerns raised and I don't have knowledgeable answers for them
at this point. So moved this to 0.16 and will add this after we actually fully understand
more about the NUMA behavior and what is happening with and without NUMA in Tez AM. 


> Add -XX:+UseNUMA for Tez jobs
> -----------------------------
>                 Key: PIG-4555
>                 URL: https://issues.apache.org/jira/browse/PIG-4555
>             Project: Pig
>          Issue Type: Improvement
>            Reporter: Rohini Palaniswamy
>            Assignee: Rohini Palaniswamy
>             Fix For: 0.16.0
>     For very big Tez jobs (~50K tasks), AM quickly goes OOM without -XX:+UseNUMA. tez.am.launch.cmd-opts
default setting has that, but since pig gives preference to yarn.app.mapreduce.am.command-opts
if present (which usually it is),  -XX:+UseNUMA is not there. Need to add -XX:+UseNUMA if
we are picking up mapreduce setting.

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