[fix]: fix ConcurrentModificationException when completing invocations

[zhongkechen]

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Issue Link, if available

Fixes: #361

Description

1. The test cases occasionally fail with ConcurrentModificationException, which is thrown when an invocation is completed and validating the operations.

SynchronizedMap was used to store the operations and the operations might be updated when validating them because operations running in the background (e.g. skipped map items) could be completed when validating.

Fix:

Replaced SynchronizedMap with ConcurrentHashMap that is safe to iterate when being updated

2. Parallel branches that are added after the parallel result is checkpointed will not exist in the checkpointed result, leading to an OutOfBoundary exception during replay and occasional test case failures.

Fix:

Check the branch's existence in the checkpointed result when adding a new branch

Demo/Screenshots

Repeated the tests 40000+ times and the exception wasn't thrown

Checklist

• I have filled out every section of the PR template
• I have thoroughly tested this change

Testing

Unit Tests

Have unit tests been written for these changes? N/A

Integration Tests

Have integration tests been written for these changes? The two bugs were caught by existing tests

Examples

Has a new example been added for the change? (if applicable)