[jira] [Commented] (CASSANDRA-6169) Too many splits causes a "OutOfMemoryError: unable to create new native thread" in AbstractColumnFamilyInputFormat

["Jonathan Ellis (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-6169?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13789902#comment-13789902 ] 

Jonathan Ellis commented on CASSANDRA-6169:
-------------------------------------------

Makes sense to me, although I'm not sure it needs to be configurable.  Picking something reasonable like 128 should be fine.

> Too many splits causes a "OutOfMemoryError: unable to create new native thread" in AbstractColumnFamilyInputFormat
> ------------------------------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-6169
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6169
>             Project: Cassandra
>          Issue Type: Bug
>         Environment: 1.2.10
> vnodes (server side)
> Mac OS x (client)
>            Reporter: Patricio Echague
>            Priority: Minor
>              Labels: hadoop
>
> The problem is caused by having 2300+ tokens due to vnodes.
> In the client side I get this exception
> {code}
> Exception in thread "main" java.lang.OutOfMemoryError: unable to create new native thread
> 	at java.lang.Thread.start0(Native Method)
> 	at java.lang.Thread.start(Thread.java:691)
> 	at java.util.concurrent.ThreadPoolExecutor.addWorker(ThreadPoolExecutor.java:943)
> 	at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1336)
> 	at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:132)
> 	at org.apache.cassandra.hadoop.AbstractColumnFamilyInputFormat.getSplits(AbstractColumnFamilyInputFormat.java:187)
> 	at org.apache.hadoop.mapred.JobClient.writeNewSplits(JobClient.java:1054)
> 	at org.apache.hadoop.mapred.JobClient.writeSplits(JobClient.java:1071)
> 	at org.apache.hadoop.mapred.JobClient.access$700(JobClient.java:179)
> 	at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:983)
> 	at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:936)
> 	at java.security.AccessController.doPrivileged(Native Method)
> 	at javax.security.auth.Subject.doAs(Subject.java:415)
> 	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1190)
> 	at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:936)
> 	at org.apache.hadoop.mapreduce.Job.submit(Job.java:550)
> 	at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:580)
> 	at com.relateiq.hadoop.cassandra.etl.CassandraETLJob.run(CassandraETLJob.java:58)
> 	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
> 	at com.relateiq.hadoop.cassandra.etl.CassandraETLJob.main(CassandraETLJob.java:149)
> {code}
> The problem seem to be in AbstractColumnFamilyInputFormat line ~180 which has an unbounded upper limit (actually it is Integer.MAX_INT)
> {code}
> ExecutorService executor = Executors.newCachedThreadPool();
> {code}
> Followed by:
> {code}
>             for (TokenRange range : masterRangeNodes)
>             {
>                 if (jobRange == null)
>                 {
>                     // for each range, pick a live owner and ask it to compute bite-sized splits
>                     splitfutures.add(executor.submit(new SplitCallable(range, conf)));
>                 }
>                 else
>                 .....
> {code}
> which gets called one time per token and creates one thread just as many times.
> The easy fix unless there is a longer term fix I'm unaware of would be to set an upper limit to the thread pool.
> Something like this:
> {code}
> ExecutorService executor = new ThreadPoolExecutor(0, ConfigHelper.getMaxConcurrentSplitsResolution(), 60L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>());
> {code}
> Shall I proceed with a patch ?



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