> This PR covers a number of issues with j.l.management.ThreadMXBean, and the > JDK-specific extension c.s.management.ThreadMXBean, when there are virtual > threads in use. > > As background, ThreadMXBean was re-specified in Java 19 to support the > monitoring and management of platform threads. It does not support virtual > threads as their potential number, and the need to find a thread by id, does > not make sense for this API. At the same time, JDK 19 introduced an > alternative implementation of virtual threads for Zero and ports without > continuations support in the VM. This alternative implementation of virtual > threads means a JavaThread per virtual thread and so requires filtering to > ensure that the API behaves as specified. For the initial implementation, the > filtering was done in the ThreadMXBean implementation. That works for most > functions but not for getThreadXXXTime(long[]) and > getThreadAllocatedBytes(long[]) where the filtering needs to be pushed down > to the management code. > > The changes in this PR move the filtering to the management functions > (jmm_XXX) so they only return information about platform threads. It also > fixes ThreadMXBean.getCurrentThreadCpuTime and getCurrentThreadUserTime to > not throw UOE when CPU time measurement from a platform thread is supported. > There are some small adjustments to the API docs (see linked CSR). Test > coverage is expanded as we didn't include tests for > c.s.management.ThreadMXBean with virtual threads in JDK 19. > > Testing tier1-3 (jdk_management test group is in test/jdk/:tier3), plus > sanity checking that --with-jvm-variants=minimal builds as some of this code > is not compiled in with minimal VM builds.
Alan Bateman 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 eight additional commits since the last revision: - Tweak javadoc to avoid listing too many conditions in @return description - Merge - Update isXXXThreadCpuTimeSupported descriptions - Clarify Thread CPU time seciton of spec - Merge - Fix minimal build - Fix minimal build - Initial commit ------------- Changes: - all: https://git.openjdk.org/jdk/pull/12762/files - new: https://git.openjdk.org/jdk/pull/12762/files/956a1e0d..dd212cdb Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=12762&range=03 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12762&range=02-03 Stats: 1256 lines in 50 files changed: 999 ins; 156 del; 101 mod Patch: https://git.openjdk.org/jdk/pull/12762.diff Fetch: git fetch https://git.openjdk.org/jdk pull/12762/head:pull/12762 PR: https://git.openjdk.org/jdk/pull/12762
