> 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 with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 15 additional commits since the last revision: - Merge branch 'master' of https://github.com/openjdk/jdk into 8286030-avoid-jvm-crash-when-containers-share-tmp-dir - Fixed typo in comments - add errno to log - added debug log and tweaked comment - fixed typo - added more comments - Simplified code and improved comments - @tstuefe comments - Merge branch 'master' into 8286030-avoid-jvm-crash-when-containers-share-tmp-dir - Cleaned up comments and avoid using the word "resource" to describe the shared mem file - ... and 5 more: https://git.openjdk.org/jdk/compare/7575df9c...efc00f6e ------------- Changes: - all: https://git.openjdk.org/jdk/pull/9406/files - new: https://git.openjdk.org/jdk/pull/9406/files/ecac352b..efc00f6e Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=9406&range=06 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9406&range=05-06 Stats: 85601 lines in 1888 files changed: 43830 ins; 26943 del; 14828 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
