Hi Bob, Changes look OK to me.
I'd prefer if those issues would get addressed separately, though. 3 webrevs for 3 bugs, over lumping 3 bugs into 1 webrev. This makes it A) easier to review B) easier to backport to older releases if/when the time comes. Some of those issues are rather unrelated after all. Thanks, Severin On Thu, 2019-03-14 at 10:15 -0400, Bob Vandette wrote: > Ping ... > > > Please review these three fixes for Linux Docker/cgroup container > support. > > WEBREV: > > http://cr.openjdk.java.net/~bobv/8217766/webrev.0 > > ISSUE1: > > https://bugs.openjdk.java.net/browse/JDK-8219562 - Line of code in > osContainer_linux.cpp#L102 appears unreachable > > This change corrects a rarely used hotspot code path making it > compatible with the Java based Metrics. > > ISSUE2: > > https://bugs.openjdk.java.net/browse/JDK-8212528 - Wrong cgroup > subsystem being used for some CPU Container Metrics > > Most Linux distros provide symbolic links for cpuacct and cpu > controller directories. Docker on the Mac does not. > This causes some of the cpu statistics to be unreported since the > directory name was incorrect. > > ISSUE3: > > https://bugs.openjdk.java.net/browse/JDK-8217766 - Container Support > doesn't work for some Join Controllers combinations > > The cgroup identification -implemented by parsing > /proc/self/mountinfo > and /proc/self/cgroup- assumed each cgroup controller was mounted > disjoint from the others (except for "cpu" and "cpuacct" > controllers). > Which means, we expected one single controller per mountinfo line. > > This matches the way most Linux distributions currently configure > cgroupsv1 by default. Yet controllers can be grouped arbitrarily. > For instance, using the systemd directive. > One use case for that is to let Kubernetes' kubelet discover his own > dedicated and reserved cgroup hierarchy. In that situation, the JVM > fails to discover the expected cgroup controllers set, and, when > running > containerized, default to a suboptimal understanding of available > resources. > > Supporting arbitrarily controllers groups per mountpoint actually > allows for simpler and easier to follow code, as we don't need nested > if/else for every controller. > > This fix also updates the Containers Metrics, to support joint > controllers. > > > Bob.
