On Fri, 21 Mar 2025 19:44:48 GMT, Chen Liang <li...@openjdk.org> wrote:
>> The recent patch #23866 makes calling `ClassValue::remove()` from >> `ClassValue::computeValue()` end up in infinite loops while fixing the stale >> value risk from the method. >> >> The proposed fix is to preserve the stale value risk fix, and update the >> remove-from-compute behavior from the original designated no-op behavior to >> throwing an exception, as the original behavior conflicts with the stale >> value fix. >> >> The implementation track the owner thread in promises (accessed in locked >> section); as a result, we can fail-fast on recursive removals from >> `computeValue`. I did not choose to use `ThreadTracker` as it is designed >> for single tracker and multiple threads, while this case here sees often >> just one thread, and the threads outlive the promise objects. >> >> Also updated the API specs for `remove` to more concisely describe the >> memory effects. Please review the associated CSR as well. > > Chen Liang has updated the pull request incrementally with one additional > commit since the last revision: > > docs There shouldn't be. 1. This just allocates a new promise for a single-threaded computation; the promise just holds a field unless there is racy computeValue, which is rare. Also, most of the access to ClassValue is going to find a present entry, so the computation is rare and the impact may be even smaller. 2. The Promise objects are always removed by the finally block in `getFromHashMap`, so there should not be retained memory. ------------- PR Comment: https://git.openjdk.org/jdk/pull/24043#issuecomment-2762861151
