> Some Kubernetes setups share the /tmp directory across multiple containers. > On rare occasions, the JVM may crash when it tries to write to > `/tmp/hsperfdata_<user>/<pid>` when a process in a separate container decides > to do the same thing (because they happen to have the same namespaced pid). > > This patch avoids the crash by using `flock()` to allow only one of these > processes to write to the file. All other competing processes that fail to > grab the lock will give up the file and run with PerfMemory disabled. We will > try to enable PerfMemory for the failed processes in a follow-up RFE: > [JDK-8289883](https://bugs.openjdk.org/browse/JDK-8289883) > > Thanks to Vitaly Davidovich and Nico Williams for coming up with the idea of > using `flock()`. > > I kept the use of `kill()` for stale file detection to be compatible with > older JVMs. > > I also took the opportunity to clean up the comments and remove dead code. > The old code was using "shared memory resources" which sounds unclear and > odd. I changed the terminology to say "shared memory file" instead.
Ioi Lam has updated the pull request incrementally with one additional commit since the last revision: added more comments ------------- Changes: - all: https://git.openjdk.org/jdk/pull/9406/files - new: https://git.openjdk.org/jdk/pull/9406/files/f1efc476..73242937 Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=9406&range=03 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9406&range=02-03 Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod Patch: https://git.openjdk.org/jdk/pull/9406.diff Fetch: git fetch https://git.openjdk.org/jdk pull/9406/head:pull/9406 PR: https://git.openjdk.org/jdk/pull/9406
