Python/thread.c

cpython 3.14 @ ab2d84fe1023/Python/thread.c ↗

Python/thread.c is the platform-independent threading API used by CPython internals. It sits above OS threading libraries (pthreads on POSIX, Win32 on Windows) and provides the lock and thread-local storage primitives the GIL and the import lock depend on.

Map

Lines	Symbol	Role
1-80	PyThread_start_new_thread	Launch an OS thread running a C function
81-200	PyThread_allocate_lock, PyThread_acquire_lock, PyThread_release_lock	Mutex API
201-320	Py_tss_t, PyThread_tss_create, PyThread_tss_get, PyThread_tss_set	Thread-local storage
321-520	Platform includes	thread_pthread.h or thread_nt.h via #include

Reading

PyThread_start_new_thread

// CPython: Python/thread.c:45 PyThread_start_new_thread
unsigned long
PyThread_start_new_thread(void (*func)(void *), void *arg)
{
    ...
    return _PyThread_start_new_thread(func, arg, &config);
}

The function returns the OS thread ID or 0 on failure. The new thread begins executing func(arg) immediately. No PyThreadState is created here; the C thread must call PyGILState_Ensure before using the Python API.

PyThread_acquire_lock with timeout

PyThread_acquire_lock_timed(lock, microseconds, intr_flag) supports timed acquisition. intr_flag=1 means a signal interruption returns PY_LOCK_INTR rather than retrying. This is used by threading.Lock.acquire(timeout=...).

Py_tss_t thread-local storage

Py_tss_t wraps pthread_key_t on POSIX and DWORD (TlsAlloc) on Windows. The PyThread_tss_* API is the portable way to store per-thread C pointers, used for exception state and the thread dictionary pointer.

// CPython: Python/thread.c:230 Py_tss_t
typedef struct {
    int _is_initialized;
    NATIVE_TSS_KEY_T _key;
} Py_tss_t;

gopy notes

gopy has no GIL and no OS-thread bootstrap; goroutines handle concurrency. The threading module (module/threading/) will expose Python-level Thread, Lock, and Event objects backed by Go channels and sync.Mutex. Py_tss_t has no Go analogue; goroutine-local context uses context.Context.