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https://issues.apache.org/jira/browse/MESOS-6414?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15589394#comment-15589394
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Anindya Sinha commented on MESOS-6414:
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Let us assume a task is launched which creates a sub-cgroup through an external
service. So, the cgroup hierarchy is something like:
/sys/fs/cgroup/freezer/mesos/<mesos-cgroup>/<sub-cgroup>
Say the task fails, so the container exits, and when launcher->destroy() is
called, we do a recursive cgroups::get() to get all cgroups and we get absolute
paths for both <mesos-cgroup> as well as <sub-cgroup>. And then the
TasksKiller() is initiated for <mesos-cgroup> as well as <sub-cgroup> resulting
in freeze(), thaw(), etc. for each of them in parallel, followed by a killed().
However, since the <sub-cgroup> is created by an external service, that service
may do a cleanup of <sub-cgroup> without Mesos' knowledge. If that happens,
any of the cleanup operations (freeze(), thaw(), etc) for the <sub-cgroup> may
fail in the flow of TasksKiller() for the <sub-cgroup> (since the external
service removed /sys/fs/cgroup/freezer/mesos/<mesos-cgroup>/<sub-cgroup> before
Mesos could do a cleanup in TasksKiller). As a result, we exit out of cleanup
of <mesos-cgroup> at that point which seems incorrect since all cleanup has
actually happened.
To avoid this issue (ie. race of cleanup of <sub-cgroup> between the external
service and Mesos), I am suggesting to treat failure in any of these steps as a
failure for all cases except when the failure is due to non-existence of
<sub-cgroup> (ie. it has already been cleaned up by an external service, so we
treat this as a success).
> Task cleanup fails when the containers includes cgroups not owned by Mesos
> --------------------------------------------------------------------------
>
> Key: MESOS-6414
> URL: https://issues.apache.org/jira/browse/MESOS-6414
> Project: Mesos
> Issue Type: Bug
> Components: cgroups
> Reporter: Anindya Sinha
> Assignee: Anindya Sinha
> Priority: Minor
>
> If a mesos task is launched in a cgroup outside of the context of Mesos,
> Mesos is unaware of that cgroup created in the task context.
> Now when the Mesos task terminates: Mesos tries to cleanup all cgroups within
> the top level cgroup it knows about. If the cgroup created in the task
> context exists when LinuxLauncherProcess::destroy() is called but is
> eventually cleaned up by the container before we do a freeze() or thaw() or
> remove(), it fails at those stages leading to an incomplete cleanup of the
> container.
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