On Wed, 28 Aug 2024 21:40:57 GMT, Chris Plummer <cjplum...@openjdk.org> wrote:
> Only allocate the cmdQueueLock once rather than allocate each time there is a > new connection (and destroy when the connection is terminated). > > Currently each time there is a new debug agent connection established, the > cmdQueueLock is allocated. It is then destroyed when the connection is > dropped, only to be recreated on the next connection. I looked closely at the > use of this lock, and what happens when the connection is dropped, and I > can't see any reason to create and then dispose of cmdQueueLock for each > connection. Of the 18 debug agent raw monitors, this is the only one that > gets destroyed and recreated. The other 17 stick around for the next > connection. I'd like to get rid of this reallocation in order to support > static initialization of all the debug agent raw monitors on startup. This > will be done as part of the ranked monitor support > ([JDK-8328866](https://bugs.openjdk.org/browse/JDK-8328866)). > > As part of the testing for this change, I put an assert in place when we try > to create cmdQueueLock for the 2nd time. I ran all our debugger tests, and > unfortunately none of them failed. This means we don't currently test > attaching to the debug agent more than once in any of our tests, so I did two > things to better test out this change. The first was to write a test that > attaches numerous times in sequence, and the 2nd was to manually attach and > reattach using jdb. At the same time I stepped through the debug agent code > in gdb just to help better understand the setup and use of cmdQueueLock. I > didn't see anything that gave me concern about making this change. > > Tested by running all jdi, jdwp, and jdb tests on all supported platforms. The changes looks good except one nit. test/jdk/com/sun/jdi/ReattachStressTest.java line 76: > 74: // Read the first character of output to make sure we've > waited until the > 75: // debuggee is ready. This will be the debug agent's > "Listening..." message. > 76: InputStream is = p.getInputStream(); The stream is not closed. Not sure it can cause problems but probably could once we reuse agent for tests. ------------- Marked as reviewed by lmesnik (Reviewer). PR Review: https://git.openjdk.org/jdk/pull/20755#pullrequestreview-2273078247 PR Review Comment: https://git.openjdk.org/jdk/pull/20755#discussion_r1739136266
