cf-natali commented on a change in pull request #355: Handle EBUSY when
destroying a cgroup.
URL: https://github.com/apache/mesos/pull/355#discussion_r405018860
##########
File path: src/linux/cgroups.cpp
##########
@@ -696,13 +696,24 @@ Try<Nothing> remove(const string& hierarchy, const
string& cgroup)
string path = path::join(hierarchy, cgroup);
// Do NOT recursively remove cgroups.
- Try<Nothing> rmdir = os::rmdir(path, false);
- if (rmdir.isError()) {
- return Error(
+ // TODO The retry was added as a fix for kernel bug
+ // https://lkml.org/lkml/2020/1/15/1349
+ // where calling rmdir on a seemingly empty cgroup can fail
+ // with EBUSY while some tasks are exiting.
+ auto delay = Milliseconds(1);
+ for (auto retry = 10; ;) {
+ Try<Nothing> rmdir = os::rmdir(path, false);
+ if (!rmdir.isError()) {
+ return rmdir;
+ } else if (retry > 0) {
+ os::sleep(delay);
Review comment:
Hm, I'm still confused: in your version, you capture `retry` and `delay` in
the lambdas by value, so their modifications are lost:
```
return loop(
// NOTE: copy `delay` by value in the first lambda function.
[=]() mutable {
auto timeout = process::after(delay);
delay *= 2;
return timeout;
},
// NOTE: copy `retry` by value in the second lambda function.
[=](const Nothing&) mutable -> Future<ControlFlow<Nothing>> {
[...]
} else if ((errno == EBUSY) && (retry > 0)) {
--retry;
return process::Continue();
```
I think that with this, `delay` and `retry` will *not* be updated from one
iteration to the next: so basically we will keep retrying the `rmdir` every 1ms
forever.
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