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https://issues.apache.org/jira/browse/HDFS-13393?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16665716#comment-16665716
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Wei-Chiu Chuang commented on HDFS-13393:
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Excerpt from book ??Java Performance The definitive Guide??, Chapter 7/8:
{quote}
Out of native memory
The first case in this list – no native memory available for the JVM – occurs
for reasons unrelated to the heap at all. In a 32-bit JVM, the maximum size of
a process is 4GB (3GB on some versions of Windows, and about 3.5 GB on some
older versions of Linux). Specifying a very large heap – say, 3.8GB – brings
the application size dangerously close to that limit. Even in a 64-bit JVM, the
operating system may not have sufficient virtual memory for whatever the JVM
requests.
This topic is addressed more fully in Chapter 8. Be aware that if the message
for the out of memory error discusses allocation of native memory, then heap
tuning isn't the answer: you need to look into whatever native memory issue is
mentioned in the error. For example, the following message tells you that the
native memory for that thread stacks is exhausted:
Exception in thread "main" java.lang.OutOfMemoryError: unable to create new
native thread.
{quote}
To help diagnosis, Java 8 has Native Memory Tracking
You'd need to add JVM option -XX:NativeMemoryTracking=summary (default is off)
And then use jcmd command to get native mem information:
$ jcmd process_id VM.native_memory summary
Additionally, another possibility is ulimit.
If user has set a lower max user process limit (ulimit -u), she could hit the
exact same error, totally unrelated to memory, but simply because she is not
allowed to fork any new threads.
> Improve OOM logging
> -------------------
>
> Key: HDFS-13393
> URL: https://issues.apache.org/jira/browse/HDFS-13393
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: balancer & mover, datanode
> Reporter: Wei-Chiu Chuang
> Assignee: Gabor Bota
> Priority: Major
>
> It is not uncommon to find "java.lang.OutOfMemoryError: unable to create new
> native thread" errors in a HDFS cluster. Most often this happens when
> DataNode creating DataXceiver threads, or when balancer creates threads for
> moving blocks around.
> In most of cases, the "OOM" is a symptom of number of threads reaching system
> limit, rather than actually running out of memory, and the current logging of
> this message is usually misleading (suggesting this is due to insufficient
> memory)
> How about capturing the OOM, and if it is due to "unable to create new native
> thread", print some more helpful message like "bump your ulimit" or "take a
> jstack of the process"?
> Even better, surface this error to make it more visible. It usually takes a
> while for an in-depth investigation after users notice some job fails, by the
> time the evidences may already been gone (like jstack output).
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