On Wed, 10 May 2023 23:57:47 GMT, Paul Hohensee <p...@openjdk.org> wrote:
>> Please review this addition to com.sun.management.ThreadMXBean that returns >> the total number of bytes allocated on the Java heap since JVM launch by >> both terminated and live threads. >> >> Because this PR adds a new interface method, I've updated the JMM_VERSION to >> 4, but would be happy to update it to 3_1 instead. > > Paul Hohensee has updated the pull request incrementally with one additional > commit since the last revision: > > 8304074: getTotalThreadAllocatedBytes name change, increment > exited_allocated_bytes in ThreadService::remove_thread, add 64-bit atomic add > for linux/bsd_x86, stub out for other platforms src/hotspot/share/services/management.cpp line 2107: > 2105: // twice, once in the loop and agsin in exited_allocated_bytes if > it's > 2106: // removed from the list after it's encountered in the loop but > before > 2107: // adding exited_allocated_bytes. This is not an accurate description. Once we have the TLH we have a fixed set of threads and none of them can update exited_allocated_bytes. If we read exited_allocated_bytes while the TLH is held then the count can be short for two reasons: 1. Newly started threads 2. Terminating threads that already escaped the TLH but which hadn't updated exited_allocated_bytes by the time we read it. AFAICS with the current logic there is no possibility of double-accounting. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/13814#discussion_r1190602862
