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Posted to yarn-issues@hadoop.apache.org by "Jim Brennan (JIRA)" <ji...@apache.org> on 2018/09/04 15:35:01 UTC
[jira] [Commented] (YARN-8648) Container cgroups are leaked when
using docker
[ https://issues.apache.org/jira/browse/YARN-8648?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16603202#comment-16603202 ]
Jim Brennan commented on YARN-8648:
-----------------------------------
I've uploaded a patch that addresses most of issues raised by [~jlowe] - except for moving the functionality to the Docker RM command - I wanted to put up these other changes before reworking that part.
I misspoke in my earlier comment - I don't think any change would be needed to DockerContainerDeletionService, because it ends up calling LinuxContainerExecutor.removeDockerContainer(), which can lookup the yarn-hierarchy. My only reservation to moving this to the DockerRmCommand is that most (if not all) arguments to Docker*Commands are actual command line arguments for the docker command. This would be an exception to that. Not sure how much that matters, because I agree this cleanup does naturally align with removing the container.
> Container cgroups are leaked when using docker
> ----------------------------------------------
>
> Key: YARN-8648
> URL: https://issues.apache.org/jira/browse/YARN-8648
> Project: Hadoop YARN
> Issue Type: Bug
> Reporter: Jim Brennan
> Assignee: Jim Brennan
> Priority: Major
> Labels: Docker
> Attachments: YARN-8648.001.patch, YARN-8648.002.patch
>
>
> When you run with docker and enable cgroups for cpu, docker creates cgroups for all resources on the system, not just for cpu. For instance, if the {{yarn.nodemanager.linux-container-executor.cgroups.hierarchy=/hadoop-yarn}}, the nodemanager will create a cgroup for each container under {{/sys/fs/cgroup/cpu/hadoop-yarn}}. In the docker case, we pass this path via the {{--cgroup-parent}} command line argument. Docker then creates a cgroup for the docker container under that, for instance: {{/sys/fs/cgroup/cpu/hadoop-yarn/container_id/docker_container_id}}.
> When the container exits, docker cleans up the {{docker_container_id}} cgroup, and the nodemanager cleans up the {{container_id}} cgroup, All is good under {{/sys/fs/cgroup/hadoop-yarn}}.
> The problem is that docker also creates that same hierarchy under every resource under {{/sys/fs/cgroup}}. On the rhel7 system I am using, these are: blkio, cpuset, devices, freezer, hugetlb, memory, net_cls, net_prio, perf_event, and systemd. So for instance, docker creates {{/sys/fs/cgroup/cpuset/hadoop-yarn/container_id/docker_container_id}}, but it only cleans up the leaf cgroup {{docker_container_id}}. Nobody cleans up the {{container_id}} cgroups for these other resources. On one of our busy clusters, we found > 100,000 of these leaked cgroups.
> I found this in our 2.8-based version of hadoop, but I have been able to repro with current hadoop.
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