On Mon, 29 Jul 2024 19:08:17 GMT, Sonia Zaldana Calles <szald...@openjdk.org> wrote:
>> Hi all, >> >> This PR addresses [8334492](https://bugs.openjdk.org/browse/JDK-8334492) >> enabling jcmd diagnostic commands that issue an output file to accept the >> `%p` pattern in the file name and substitute it for the PID. >> >> This PR addresses the following diagnostic commands: >> - [x] Compiler.perfmap >> - [x] GC.heap_dump >> - [x] System.dump_map >> - [x] Thread.dump_to_file >> - [x] VM.cds >> >> Note that some jcmd diagnostic commands already enable this functionality >> (`JFR.configure, JFR.dump, JFR.start and JFR.stop`). >> >> I propose opening a separate issue to track updating the man page similarly >> to how it’s done for the JFR diagnostic commands. For example, >> >> >> filename (Optional) Name of the file to which the flight recording >> data is >> written when the recording is stopped. If no filename is >> given, a >> filename is generated from the PID and the current date >> and is >> placed in the directory where the process was started. The >> filename may also be a directory in which case, the >> filename is >> generated from the PID and the current date in the >> specified >> directory. (STRING, no default value) >> >> Note: If a filename is given, '%p' in the filename will be >> replaced by the PID, and '%t' will be replaced by the >> time in >> 'yyyy_MM_dd_HH_mm_ss' format. >> >> >> Unfortunately, per [8276265](https://bugs.openjdk.org/browse/JDK-8276265), >> sources for the jcmd manpage remain in Oracle internal repos so this PR >> can’t address that. >> >> Testing: >> >> - [x] Added test case passes. >> - [x] Modified existing VM.cds tests to also check for `%p` filenames. >> >> Looking forward to your comments and addressing any diagnostic commands I >> might have missed (if any). >> >> Cheers, >> Sonia > > Sonia Zaldana Calles has updated the pull request incrementally with one > additional commit since the last revision: > > last lingering change Thanks Sonia, and thanks Thomas! I did just see a poblem with DumpPerfMapAtExit that I didn't notice before. When -XX:+DumpPerfMapAtExit causes a call to CodeCache::write_perf_map, there's now no %p substitution so /tmp/perf-%p.map gets created. We all hate duplication but CodeCache::write_perf_map has two very different callers. It could do something like this (feel free to adjust/correct/do something else): src/hotspot/share/code/codeCache.cpp #ifdef LINUX void CodeCache::write_perf_map(const char* filename, outputStream* st) { MutexLocker mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); + if (filename == nullptr) { + st->print_cr("Warning: Not writing perf map as null filename provided."); + return; + } + char fname[JVM_MAXPATHLEN]; + if (strstr(filename, "%p") != nullptr) { + // Unnecessary if filename contains %%p but will be a rare waste of time: + if (!Arguments::copy_expand_pid(filename, strlen(filename), fname, JVM_MAXPATHLEN)) { + st->print_cr("Warning: Not writing perf map as substitution failed."); + return; + } + filename = fname; + } + fileStream fs(filename, "w"); JVM_MAXPATHLEN will have a lot of slack space there as if it contains %p it really should be the default filename, so you could go with a lower value. ------------- PR Comment: https://git.openjdk.org/jdk/pull/20198#issuecomment-2257986965
