# Bug report TSan reports data races for [`test_thread_local_bytecode.test_no_copies_if_tlbc_disabled`](https://github.com/python/cpython/blob/365cf5fc23835fa6dc8608396109085f31d2d5f0/Lib/test/test_thread_local_bytecode.py#L112). ``` WARNING: ThreadSanitizer: data race (pid=1222408) Read of size 2 at 0x7fffb44d7cc2 by thread T2: #0 _PyEval_EvalFrameDefault /raid/sgross/cpython/Python/generated_cases.c.h:7283:36 (python+0x402a47) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #1 _PyEval_EvalFrame /raid/sgross/cpython/./Include/internal/pycore_ceval.h:116:16 (python+0x3f48ea) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #2 _PyEval_Vector /raid/sgross/cpython/Python/ceval.c:1761:12 (python+0x3f48ea) #3 _PyFunction_Vectorcall /raid/sgross/cpython/Objects/call.c (python+0x1ef79f) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #4 _PyObject_VectorcallTstate /raid/sgross/cpython/./Include/internal/pycore_call.h:167:11 (python+0x1f3f9f) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #5 method_vectorcall /raid/sgross/cpython/Objects/classobject.c:72:20 (python+0x1f3f9f) #6 _PyVectorcall_Call /raid/sgross/cpython/Objects/call.c:273:16 (python+0x1ef413) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #7 _PyObject_Call /raid/sgross/cpython/Objects/call.c:348:16 (python+0x1ef413) #8 PyObject_Call /raid/sgross/cpython/Objects/call.c:373:12 (python+0x1ef495) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #9 thread_run /raid/sgross/cpython/./Modules/_threadmodule.c:354:21 (python+0x58d1d2) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #10 pythread_wrapper /raid/sgross/cpython/Python/thread_pthread.h:242:5 (python+0x4e89c7) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) Previous write of size 2 at 0x7fffb44d7cc2 by main thread: #0 _PyEval_EvalFrameDefault /raid/sgross/cpython/Python/generated_cases.c.h:7295:17 (python+0x402af4) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #1 _PyEval_EvalFrame /raid/sgross/cpython/./Include/internal/pycore_ceval.h:116:16 (python+0x3f48ea) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #2 _PyEval_Vector /raid/sgross/cpython/Python/ceval.c:1761:12 (python+0x3f48ea) #3 PyEval_EvalCode /raid/sgross/cpython/Python/ceval.c:662:21 (python+0x3f43fd) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #4 run_eval_code_obj /raid/sgross/cpython/Python/pythonrun.c:1331:9 (python+0x4c6e2e) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #5 run_mod /raid/sgross/cpython/Python/pythonrun.c:1406:19 (python+0x4c6b5f) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #6 _PyRun_StringFlagsWithName /raid/sgross/cpython/Python/pythonrun.c:1215:15 (python+0x4c3a75) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #7 _PyRun_SimpleStringFlagsWithName /raid/sgross/cpython/Python/pythonrun.c:548:15 (python+0x4c3a75) #8 pymain_run_command /raid/sgross/cpython/Modules/main.c:253:11 (python+0x502c21) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #9 pymain_run_python /raid/sgross/cpython/Modules/main.c:678:21 (python+0x502c21) #10 Py_RunMain /raid/sgross/cpython/Modules/main.c:766:5 (python+0x502c21) #11 pymain_main /raid/sgross/cpython/Modules/main.c:796:12 (python+0x5031b8) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #12 Py_BytesMain /raid/sgross/cpython/Modules/main.c:820:12 (python+0x50323b) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) #13 main /raid/sgross/cpython/./Programs/python.c:15:12 (python+0x16417b) (BuildId: d2c9a0e659ee21e3ff5331c41d7aa75d7fd2bc90) ``` The races are on the adaptive counter: https://github.com/python/cpython/blob/365cf5fc23835fa6dc8608396109085f31d2d5f0/Python/generated_cases.c.h#L7283 https://github.com/python/cpython/blob/365cf5fc23835fa6dc8608396109085f31d2d5f0/Python/generated_cases.c.h#L7295 <!-- gh-linked-prs --> ### Linked PRs * gh-155497 * gh-155647 * gh-155715 <!-- /gh-linked-prs -->