Prevent deadlock in java.base creation #19458
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Thread 1 creates java.base: - acquires module (classLoaderModuleAndLocationMutex) mutex - acquires class mutex (classTableMutex) to update all bootstrap classes Thread 2 loads a class - aquires class mutex - acquire module mutex to search for class location There is a scenario where Thread 1 acquires module mutex, then thread 2 acquires class mutex. Thread 1 cannot complete creating java.base because it needs the class mutex and Thread 2 cannot complete class loading because it needs the module mutex. Proposed solution is for Thread 1 to acquire the class mutex first if it is known that it will be needed. Related: eclipse-openj9#19439 Signed-off-by: tajila <[email protected]>
|
jenkins test sanity alinux64 jdk23 |
|
jenkins test sanity alinux64 jdknext |
|
@gacholio please review |
gacholio
approved these changes
May 10, 2024
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Thread 1 creates java.base:
Thread 2 loads a class
There is a scenario where Thread 1 acquires module mutex, then thread 2 acquires class mutex. Thread 1 cannot complete creating java.base because it needs the class mutex and Thread 2 cannot complete class loading because it needs the module mutex.
Related: #19439
Proposed solution is for Thread 1 to acquire the class mutex first if it is known that it will be needed.