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https://issues.apache.org/jira/browse/MESOS-8480?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16336710#comment-16336710
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Jie Yu commented on MESOS-8480:
-------------------------------
commit 1382e595fa5e82f9917df97fbed76f77140ecc1e (HEAD -> master, origin/master,
origin/HEAD)
Author: Chun-Hung Hsiao <[email protected]>
Date: Tue Jan 23 17:13:05 2018 -0800
Fixed resource statistics for Docker containers being destroyed.
If a process has exited, but not reaped yet (zombie procses),
`/proc/<pid>/cgroup` will still exist, but the process's cgroup will be
reset to the root cgroup. In DockerContainerizer, we rely on
`/proc/<pid>/cgroup` to get the cpu/memory statistics of the container.
If the `usage` call happens when the process is a zombie, the cpu/memory
statistics will actually be that of the root cgroup, which is obviously
not correct. See more details in MESOS-8480.
This patch fixed the issue by checking if the cgroup of a given pid is
root cgroup or not.
Review: https://reviews.apache.org/r/65301/
> Mesos returns high resource usage when killing a Docker task.
> -------------------------------------------------------------
>
> Key: MESOS-8480
> URL: https://issues.apache.org/jira/browse/MESOS-8480
> Project: Mesos
> Issue Type: Bug
> Components: cgroups
> Reporter: Chun-Hung Hsiao
> Assignee: Chun-Hung Hsiao
> Priority: Major
> Fix For: 1.6.0
>
> Attachments: test.cpp
>
>
> The way we get resource statistics for Docker tasks is through getting the
> cgroup subsystem path through {{/proc/<pid>/docker}} first (taking the
> {{cpuacct}} subsystem as an example):
> {noformat}
> 9:cpuacct,cpu:/docker/66fbe67b64ad3a86c6e080e18578bc9e540e55ee0bdcae09c2e131a4264a3a3b
> {noformat}
> Then read
> {{/sys/fs/cgroup/cpuacct//docker/66fbe67b64ad3a86c6e080e18578bc9e540e55ee0bdcae09c2e131a4264a3a3b/cpuacct.stat}}
> to get the statistics:
> {noformat}
> user 4
> system 0
> {noformat}
> However, when a Docker container is being teared down, it seems that Docker
> or the operation system will first move the process to the root cgroup before
> actually killing it, making {{/proc/<pid>/docker}} look like the following:
> {noformat}
> 9:cpuacct,cpu:/
> {noformat}
> This makes a racy call to
> [{{cgroup::internal::cgroup()}}|https://github.com/apache/mesos/blob/master/src/linux/cgroups.cpp#L1935]
> return a single '/', which in turn makes
> [{{DockerContainerizerProcess::cgroupsStatistics()}}|https://github.com/apache/mesos/blob/master/src/slave/containerizer/docker.cpp#L1991]
> read {{/sys/fs/cgroup/cpuacct///cpuacct.stat}}, which contains the
> statistics for the root cgroup:
> {noformat}
> user 228058750
> system 24506461
> {noformat}
> This can be reproduced by [^test.cpp] with the following command:
> {noformat}
> $ docker run --name sleep -d --rm alpine sleep 1000; ./test $(docker inspect
> sleep | jq .[].State.Pid) & sleep 1 && docker rm -f sleep
> ...
> Reading file '/proc/44224/cgroup'
> Reading file
> '/sys/fs/cgroup/cpuacct//docker/1d79a6c877e2af3081630aa57d23d853e6bd7d210dad28f897556bfea20bc9c1/cpuacct.stat'
> user 4
> system 0
> Reading file '/proc/44224/cgroup'
> Reading file '/sys/fs/cgroup/cpuacct///cpuacct.stat'
> user 228058750
> system 24506461
> Reading file '/proc/44224/cgroup'
> Reading file '/sys/fs/cgroup/cpuacct///cpuacct.stat'
> user 228058750
> system 24506461
> Failed to open file '/proc/44224/cgroup'
> sleep
> [2]- Exit 1 ./test $(docker inspect sleep | jq
> .[].State.Pid)
> {noformat}
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