On Mon, 27 Feb 2023 12:23:09 GMT, Alan Bateman <al...@openjdk.org> wrote:
> 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. This pull request has now been integrated. Changeset: 629a9053 Author: Alan Bateman <al...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/629a9053f072a3d8406b923f8fa8ab7056a1ab8d Stats: 531 lines in 8 files changed: 285 ins; 138 del; 108 mod 8303242: ThreadMXBean issues with virtual threads Reviewed-by: mchung, pchilanomate ------------- PR: https://git.openjdk.org/jdk/pull/12762
