> On June 11, 2016, 2:31 p.m., Qian Zhang wrote:
> > src/slave/containerizer/mesos/isolators/cgroups/cgroups.cpp, line 131
> > <https://reviews.apache.org/r/46158/diff/2/?file=1347650#file1347650line131>
> >
> > I think there is a special case that we need to handle: In the OS using
> > systemd (e.g., RHEL 7.1), `cpu` and `cpuacct` subsystems are co-mounted,
> > like this:
> > ```
> > ls -la /sys/fs/cgroup/
> > ...
> > lrwxrwxrwx. 1 root root 11 Dec 28 15:12 cpu -> cpu,cpuacct
> > lrwxrwxrwx. 1 root root 11 Dec 28 15:12 cpuacct -> cpu,cpuacct
> > drwxr-xr-x. 4 root root 0 Jan 2 17:01 cpu,cpuacct
> > ...
> > ```
> > That means in this `hierarchies` hashmap, the values of the two keys
> > `cpu` and `cpuacct` are same (both of them are
> > `/sys/fs/cgroup/cpu,cpuacct`), this will cause an issue in
> > `CgroupsIsolatorProcess::prepare()`: In this method, we will call
> > `prepareHierarchy()` which will check if the cgroup for the container to be
> > creatd exists or not, if not, create the cgroup, if yes, return an Error.
> > For the OS using systemd, I think we will always get the Error since for
> > both `cpu` and `cpuacct` subsystems, we will try to create cgroup in the
> > same location, i.e., `/sys/fs/cgroup/cpu,cpuacct/mesos/<containerID>`.
> >
> > You can take a look at the following code in the existing
> > `CgroupsCpushareIsolatorProcess` class for how we handle this case.
> > https://github.com/apache/mesos/blob/0.28.2/src/slave/containerizer/mesos/isolators/cgroups/cpushare.cpp#L94:L144
Because we use
```
foreach (const string& hierarchy, info->subsystems.keys()) {
```
this problem would not happen.
Suppose both `cpu` and `cpuacct` mount to `/sys/fs/cgroup/cpu,cpuacct`. The
`info->subsystems.keys()` only have one `/sys/fs/cgroup/cpu,cpuacct` here.
- haosdent
-----------------------------------------------------------
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https://reviews.apache.org/r/46158/#review136998
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On April 16, 2016, 10:14 a.m., haosdent huang wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/46158/
> -----------------------------------------------------------
>
> (Updated April 16, 2016, 10:14 a.m.)
>
>
> Review request for mesos, Gilbert Song, Guangya Liu, Ian Downes, Jie Yu, and
> Kevin Klues.
>
>
> Bugs: MESOS-5041
> https://issues.apache.org/jira/browse/MESOS-5041
>
>
> Repository: mesos
>
>
> Description
> -------
>
> Completed implementation of the cgroups unified isolator.
>
>
> Diffs
> -----
>
> src/slave/containerizer/mesos/isolators/cgroups/cgroups.cpp PRE-CREATION
>
> Diff: https://reviews.apache.org/r/46158/diff/
>
>
> Testing
> -------
>
>
> Thanks,
>
> haosdent huang
>
>
