On Mon, 16 Aug 2021 17:25:57 GMT, Harold Seigel <[email protected]> wrote:
> Please review this small fix for JDK-8272124. The fix puts a limit of 3 when
> splitting self cgroup lines by ':' so that Cgroup paths won't get truncated
> if they contain embedded ':'s. For example, an entry of
> "11:memory:/user.sli:ce" in a /proc/self/cgroup file will now result in a
> Cgroup path of "/user.sli:ce" instead of "/user.sli".
>
> The fix was tested with Mach5 tiers 1 and 2, and Mach5 tiers 3-5 on Linux x64
> and Linux aarch64.
>
> Thanks, Harold
src/java.base/linux/classes/jdk/internal/platform/CgroupSubsystemFactory.java
line 199:
> 197: action = (tokens -> setCgroupV2Path(infos, tokens));
> 198: }
> 199: selfCgroupLines.map(line -> line.split(":", 3))
Could you please add a comment explaining that the limit value of 3 comes from
the fact that `/proc/self/cgroup` contains three colon-separated tokens per
line. The last value, cgroup path, might contain `:`.
src/java.base/linux/classes/jdk/internal/platform/CgroupSubsystemFactory.java
line 200:
> 198: }
> 199: selfCgroupLines.map(line -> line.split(":", 3))
> 200: .filter(tokens -> (tokens.length >= 3))
This filter no longer makes sense as tokens.length == 3 in every case after
this patch. Please remove. From the javadoc from `String.split(String, limit)`:
If the limit is positive then the pattern will be applied
at most limit-1 times, the array's length will be
no greater than limit, and the array's last entry will contain
all input beyond the last matched delimiter.
test/jdk/jdk/internal/platform/cgroup/TestCgroupSubsystemFactory.java line 175:
> 173: private String mntInfoCgroupsV1DoubleCpuset = mntInfoHybrid +
> mntInfoCgroupv1MoreCpusetLine;
> 174: private String mntInfoCgroupsV1DoubleCpuset2 =
> mntInfoCgroupv1MoreCpusetLine + mntInfoHybrid;
> 175: private String cgroupv1SelfCgroupContent =
> "11:memory:/user.slice/user-1000.slice/[email protected]:ervice\n" +
Could you please add a comment explaining that `/proc/self/cgroup` is supposed
to contain **three** colon-separated fields,
`hierarchy-ID:controller-list:cgroup-path`. Thus, this cgroup-path
intentionally contains a colon so as to ensure the correct path is being
extracted by the logic in CgroupSubsystemFactory.
Better yet, add a new test with `mountinfo` and `/proc/self/cgroup` contents
observed in the wild and assert that `memoryInfo.getCgroupPath()` equals
`memoryInfo.getMountRoot()`
-------------
PR: https://git.openjdk.java.net/jdk/pull/5127
