Month: 2025-04 Overview: Focused on improving reliability and correctness of AsyncGetCallTrace in corretto/corretto-17. Implemented a targeted fix that removes a legacy is_in_asgct helper and relies on Thread::current_in_asgct() for thread-state checks. Removed the _in_asgct field in JavaThread to simplify state tracking and reduce complexity in trace collection. Key features delivered: - AsyncGetCallTrace reliability fix in corretto-17, ensuring correct thread-state checks during call trace collection. Major bugs fixed: - Resolved a guarantee failure path inside AsyncGetCallTrace related to is_result_safe || is_in_asgct() by adopting Thread::current_in_asgct() and removing the now-unused is_in_asgct path. - Eliminated dependence on JavaThread._in_asgct field, reducing complexity and potential sources of state mismatch. Overall impact and accomplishments: - Increased profiling accuracy and reliability for AsyncGetCallTrace, leading to more trustworthy diagnostics and fewer false negatives/positives in traces. - Improved maintainability by removing obsolete fields and simplifying thread-state checks, with a clear, auditable commit trail. Technologies/skills demonstrated: - JVM internals debugging and state management (Thread::current_in_asgct(), call trace collection) - Refactoring and cleanup (removal of is_in_asgct helper and _in_asgct field) - Change-tracking and cross-repo alignment (linkage to specific commit fixing the issue)

2024-10 monthly summary: Stabilized the profiling subsystem in corretto-8 by delivering a targeted crash fix in AsyncGetCallTrace. The fix restores the in_asgct thread state before returning, preventing unsafe access to zombie methods and eliminating a profiler crash during performance analysis. This reduces profiling-related outages and improves reliability for Java workload tuning. The change is isolated to the profiling/trace path with a single commit, minimizing risk and enabling fast validation.