Severin, Don’t we need the contents of /proc/self/mountinfo in order to construct the path to the cgroup controllers?
On Thu, 2020-02-20 at 14:50 +0000, Baesken, Matthias wrote: > Hi Severin, > > grep cgroup /proc/self/mountinfo > > returns nothing. > > Best Regards, Matthias > Assuming your fix is correct, don’t we also need to apply the same change to the hotspot source cgroupSubsystem_linux.cpp? Bob; > On Feb 21, 2020, at 8:32 AM, Severin Gehwolf <sgehw...@redhat.com> wrote: > > Hi, > > Could I please get a review of this fix to the detection heuristic of > cgroup v1 vs cgroup v2? Matthias (in CC) discovered that on some old > systems the JDK Metrics code throws InternalError caused by wrong > detection logic when Metrics are being created on Linux. > > The reason for this is that hierarchy IDs of 0 in /proc/cgroups is > being used as a heuristic to detect cgroups v2 systems. Apparently some > old systems like RHEL 6 and SLES 11 have no cgroups controllers > mounted, thus, triggering a false positive. > > The fix is to also look at /proc/self/mountinfo and correct logic in > this case. > > Bug: https://bugs.openjdk.java.net/browse/JDK-8239559 > webrev: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8239559/01/webrev/ > > Testing: docker/cgroups tests on hybrid (cgroups v1) and unified > hierarchy (cgroups v2). New regression test. Looks good here. > > Unfortunately, I wasn't able to reproduce this on an actual affected > system. I somewhat reproduced via the derived regression test based on > data from reporters. I'd appreciate any testing on systems where this > reproduces. > > Thanks, > Severin >
