Read-acquire Class Unload Mutex for compilation before checkpoint (0.38) #17150
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The following deadlock is possible: 1. Comp thread read-enters class unload mutex 2. Checkpointing thread acquires comp monitor 3. Comp thread blocks trying to acquire comp monitor 4. Checkpointing thread blocks trying to write-enter class unload mutex The reason the Checkpointing thread acquires the class unload mutex is to prevent class unloading while it collects methods. However, a read-acquire is sufficient for this task. Therefore, having the Checkpointing thread do a read-acquire will prevent the deadlock since it will not block waiting to enter. Signed-off-by: Irwin D'Souza <dsouzai.gh@gmail.com>
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@mpirvu could you review/merge? |
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Cherry-pick of #17136 and #17143 (squashed into one commit)