ThreadSanitizer validation

The ThreadSanitizer (TSan) profile is a focused race-detection check for SDK-owned concurrency. It uses Clang with -fsanitize=thread -fno-omit-frame-pointer, builds only the selected test executables, and runs tests carrying the tsan CTest label.

Run the same profile as CI from the repository root:

./scripts/run_thread_sanitizer.sh

Set A2A_TSAN_BUILD_DIR to use a build directory other than build-tsan. Set A2A_TSAN_CXX_COMPILER to select a particular Clang executable. TSAN_OPTIONS may also be set by a developer; CI uses the script default, halt_on_error=1.

Test selection

The profile covers:

• stream-handle lifecycle, cancellation, and cancellation-watcher coordination;
• the shared HTTP client reactor and dispatch executor lifecycle;
• HTTP+JSON and JSON-RPC streaming, including cancellation;
• subscription publication, cancellation, and shutdown;
• in-memory task-store behavior; and
• dispatcher and task-store integration.

The concrete executables are listed in scripts/run_thread_sanitizer.sh. Their discovered tests carry the tsan label in tests/CMakeLists.txt. To extend the profile, add the executable to the script’s TARGETS array and label its gtest_discover_tests call with LABELS "tsan".

PostgreSQL and gRPC transport integration tests are intentionally outside this focused profile. They add third-party runtime activity without improving coverage of the synchronization primitives targeted here. The selected HTTP tests retain libcurl coverage because the shared reactor is one of the principal race-detection targets.

No TSan suppression file is used. A report in the selected tests is therefore a failure. If verified third-party noise appears in the future, prefer narrowing the test selection; any unavoidable suppression must identify the specific external symbol and document the supporting investigation here.