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https://issues.apache.org/jira/browse/YARN-1284?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13789864#comment-13789864
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Sandy Ryza commented on YARN-1284:
----------------------------------
Oh, and also:
{code{
+ if (! new File(cgroupPath).delete()) {
+ LOG.warn("Unable to delete cgroup at: " + cgroupPath +", tried to delete
for " +
+ deleteCgroupTimeout + "ms");
}
{code}
If the file was already deleted, delete() will return false and we'll log the
warning even though nothing went wrong. Instead, we should just check "if
(!deleted)".
> LCE: Race condition leaves dangling cgroups entries for killed containers
> -------------------------------------------------------------------------
>
> Key: YARN-1284
> URL: https://issues.apache.org/jira/browse/YARN-1284
> Project: Hadoop YARN
> Issue Type: Bug
> Components: nodemanager
> Affects Versions: 2.2.0
> Reporter: Alejandro Abdelnur
> Assignee: Alejandro Abdelnur
> Priority: Blocker
> Attachments: YARN-1284.patch, YARN-1284.patch, YARN-1284.patch
>
>
> When LCE & cgroups are enabled, when a container is is killed (in this case
> by its owning AM, an MRAM) it seems to be a race condition at OS level when
> doing a SIGTERM/SIGKILL and when the OS does all necessary cleanup.
> LCE code, after sending the SIGTERM/SIGKILL and getting the exitcode,
> immediately attempts to clean up the cgroups entry for the container. But
> this is failing with an error like:
> {code}
> 2013-10-07 15:21:24,359 WARN
> org.apache.hadoop.yarn.server.nodemanager.LinuxContainerExecutor: Exit code
> from container container_1381179532433_0016_01_000011 is : 143
> 2013-10-07 15:21:24,359 DEBUG
> org.apache.hadoop.yarn.server.nodemanager.containermanager.container.Container:
> Processing container_1381179532433_0016_01_000011 of type
> UPDATE_DIAGNOSTICS_MSG
> 2013-10-07 15:21:24,359 DEBUG
> org.apache.hadoop.yarn.server.nodemanager.util.CgroupsLCEResourcesHandler:
> deleteCgroup:
> /run/cgroups/cpu/hadoop-yarn/container_1381179532433_0016_01_000011
> 2013-10-07 15:21:24,359 WARN
> org.apache.hadoop.yarn.server.nodemanager.util.CgroupsLCEResourcesHandler:
> Unable to delete cgroup at:
> /run/cgroups/cpu/hadoop-yarn/container_1381179532433_0016_01_000011
> {code}
> CgroupsLCEResourcesHandler.clearLimits() has logic to wait for 500 ms for AM
> containers to avoid this problem. it seems this should be done for all
> containers.
> Still, waiting for extra 500ms seems too expensive.
> We should look at a way of doing this in a more 'efficient way' from time
> perspective, may be spinning while the deleteCgroup() cannot be done with a
> minimal sleep and a timeout.
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