Olaf Flebbe created BIGTOP-2663:
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Summary: puppet hadoop module: Consolidate memory resource
settings
Key: BIGTOP-2663
URL: https://issues.apache.org/jira/browse/BIGTOP-2663
Project: Bigtop
Issue Type: Bug
Affects Versions: 1.1.0
Reporter: Olaf Flebbe
Assignee: Olaf Flebbe
Fix For: 1.2.0
The memory resource settings for hadoop are outdated.
Now the settings in mapred-site.xml should be used
{code}
mapreduce.map.java.opts
mapreduce.reduce.java.opts
{code}
These are set now to {{-Xmx1024m}} (This was hardcoded before)
Additionally one can now optionally set the maxmimum (resident) memory
for map and reduce jobs
{code}
mapreduce.map.memory.mb
mapreduce.reduce.memory.mb
{code}
And last but not least, will set {{yarn.nodemanager.vmem-pmem-ratio}} to 100:
There is the public misconception that virtual memory is a limiting resource.
That's only the case for 32Bit Adress spaces, not anymore.
See for instance for
http://stackoverflow.com/questions/561245/virtual-memory-usage-from-java-under-linux-too-much-memory-used
for an rather up to date detailled explanation, why vmem doesn't matter.
So we allow it to be tremendiously large. Why does it matter, anyhow? Java8
seems to use memory mapped I/O agressivly now, and the virtual memory in the
hadoop mapred container became exhausted when the resident memory is only 15%
used.
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