…erence library (#268)

…eness tracking (#262)

* Merge from main

* Implement liveness-aware CallTraceStorage with dropped trace handling

Major architectural changes:
- Replace monolithic CallTraceStorage with double-buffered hash table design
- Add CallTraceHashTable with lock-free concurrent access and instance-based trace IDs
- Implement liveness tracking system to preserve active traces across JFR dumps
- Add dropped trace handling for lock contention with proper JFR integration

Key features:
- 64-bit trace IDs combining instance ID and slot for collision avoidance
- Split-lock strategy minimizing exclusive lock time during trace collection
- Platform-specific ASGCT_CallFrame alignment using LP64_ONLY macro
- Comprehensive test coverage including contention and liveness scenarios

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

* Cleanup gtest tests

* Update ddprof-test/src/test/java/com/datadoghq/profiler/memleak/LivenessTrackingTest.java

Co-authored-by: Copilot <[email protected]>

* Update ddprof-test/src/test/java/com/datadoghq/profiler/ContendedCallTraceStorageTest.java

Co-authored-by: Copilot <[email protected]>

* Bump codeql version to make CI pass

* Try using nullptr

* Add comment for CallTraceStorage::processTraces

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Co-authored-by: Claude <[email protected]>
Co-authored-by: Copilot <[email protected]>

* Thread filter optim
- Reserve padded slots for thread context to avoid false sharing.
- Introduce a register thread, unregister thread operation to retrieve slots IDs
- Manage a free list of SlotIDs
- Store the slot of a given thread within the profiledThread object

* Exterminate the last remnants of false sharing
The free list was causing false sharing.

* Adjust ThreadEnd hook
If the TLS cleanup fires before the JVMTI hook, we want to
ensure that we don't crash while retrieving the ProfiledThread

* Thread filter bench
- Start the profiler to ensure we have valid thread objects
- Add asserts around missing thread object

Many thanks for the reviews from Zhengyu.
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Co-authored-by: Jaroslav Bachorik <[email protected]>

* Fix the benchmarks

* Fix

* Relax memory constraint on counter

* test

* Revert test

* Fixed heap

* additional counters

* One more