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. This pull request has now been integrated. Changeset: 5ebdf2d2 Author: Chris Plummer <cjplum...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/5ebdf2d2720b82c4e9783fc6a9aa58344d5e2f2a Stats: 131 lines in 2 files changed: 128 ins; 1 del; 2 mod 8338708: Don't create/destroy debug agent cmdQueueLock for each connection Reviewed-by: amenkov, lmesnik ------------- PR: https://git.openjdk.org/jdk/pull/20755
