On Thu, 12 May 2022 18:09:40 GMT, Severin Gehwolf <sgehw...@openjdk.org> wrote:
>> Please review this change to the cgroup v1 subsystem which makes it more >> resilient on some of the stranger systems. Unfortunately, I wasn't able to >> re-create a similar system as the reporter. The idea of using the longest >> substring match for the cgroupv1 file paths was based on the fact that on >> systemd systems processes run in separate scopes and the maven forked test >> runner might exhibit this property. For that it makes sense to use the >> common ancestor path. Nothing changes in the common cases where the >> `cgroup_path` matches `_root` and when the `_root` is `/` (container the >> former, host system the latter). >> >> In addition, the code paths which are susceptible to throw NPE have been >> hardened to catch those situations. Should it happen in the future it makes >> more sense (to me) to not have accurate container detection in favor of >> continuing to keep running. >> >> Finally, with the added unit-tests a bug was uncovered on the "substring" >> match case of cgroup paths in hotspot. `p` returned from `strstr` can never >> point to `_root` as it's used as the "needle" to find in "haystack" >> `cgroup_path` (not the other way round). >> >> Testing: >> - [x] Added unit tests >> - [x] GHA >> - [x] Container tests on cgroups v1 Linux. Continue to pass > > Severin Gehwolf has updated the pull request incrementally with one > additional commit since the last revision: > > Use stringStream to simplify controller path assembly src/hotspot/os/linux/cgroupV1Subsystem_linux.cpp line 92: > 90: } > 91: ss.print_raw(_root, last_matching_slash_pos); > 92: _path = os::strdup(ss.base()); Do you mean `Find the longest common prefix`? Maybe give an example in the comments? Text parsing in C code is really difficult to understand. ------------- PR: https://git.openjdk.java.net/jdk/pull/8629
