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Merge in the new GIL.

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This commit is contained in:
Antoine Pitrou 2009-11-10 19:50:40 +00:00
parent 434736a1a6
commit 074e5ed974
10 changed files with 522 additions and 73 deletions
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8
Include/ceval.h
View file

@ -112,10 +112,6 @@ PyAPI_FUNC(PyObject *) PyEval_GetCallStats(PyObject *);
PyAPI_FUNC(PyObject *) PyEval_EvalFrame(struct _frame *);
PyAPI_FUNC(PyObject *) PyEval_EvalFrameEx(struct _frame *f, int exc);
/* this used to be handled on a per-thread basis - now just two globals */
PyAPI_DATA(volatile int) _Py_Ticker;
PyAPI_DATA(int) _Py_CheckInterval;
/* Interface for threads.
A module that plans to do a blocking system call (or something else
@ -174,6 +170,9 @@ PyAPI_FUNC(void) PyEval_AcquireThread(PyThreadState *tstate);
PyAPI_FUNC(void) PyEval_ReleaseThread(PyThreadState *tstate);
PyAPI_FUNC(void) PyEval_ReInitThreads(void);
PyAPI_FUNC(void) _PyEval_SetSwitchInterval(unsigned long microseconds);
PyAPI_FUNC(unsigned long) _PyEval_GetSwitchInterval(void);
#define Py_BEGIN_ALLOW_THREADS { \
PyThreadState *_save; \
_save = PyEval_SaveThread();
@ -192,6 +191,7 @@ PyAPI_FUNC(void) PyEval_ReInitThreads(void);
#endif /* !WITH_THREAD */
PyAPI_FUNC(int) _PyEval_SliceIndex(PyObject *, Py_ssize_t *);
PyAPI_FUNC(void) _PyEval_SignalAsyncExc(void);
#ifdef __cplusplus

2
Include/pystate.h
View file

@ -88,6 +88,8 @@ typedef struct _ts {
PyObject *dict; /* Stores per-thread state */
/* XXX doesn't mean anything anymore (the comment below is obsolete)
=> deprecate or remove? */
/* tick_counter is incremented whenever the check_interval ticker
* reaches zero. The purpose is to give a useful measure of the number
* of interpreted bytecode instructions in a given thread. This

1
Include/sysmodule.h
View file

@ -18,7 +18,6 @@ PyAPI_FUNC(void) PySys_WriteStderr(const char *format, ...)
Py_GCC_ATTRIBUTE((format(printf, 1, 2)));
PyAPI_DATA(PyObject *) _PySys_TraceFunc, *_PySys_ProfileFunc;
PyAPI_DATA(int) _PySys_CheckInterval;
PyAPI_FUNC(void) PySys_ResetWarnOptions(void);
PyAPI_FUNC(void) PySys_AddWarnOption(const wchar_t *);

15
Lib/test/test_sys.py
View file

@ -154,6 +154,21 @@ def test_setcheckinterval(self):
sys.setcheckinterval(n)
self.assertEquals(sys.getcheckinterval(), n)
def test_switchinterval(self):
self.assertRaises(TypeError, sys.setswitchinterval)
self.assertRaises(TypeError, sys.setswitchinterval, "a")
self.assertRaises(ValueError, sys.setswitchinterval, -1.0)
self.assertRaises(ValueError, sys.setswitchinterval, 0.0)
orig = sys.getswitchinterval()
# sanity check
self.assertTrue(orig < 0.5, orig)
try:
for n in 0.00001, 0.05, 3.0, orig:
sys.setswitchinterval(n)
self.assertAlmostEquals(sys.getswitchinterval(), n)
finally:
sys.setswitchinterval(orig)
def test_recursionlimit(self):
self.assertRaises(TypeError, sys.getrecursionlimit, 42)
oldlimit = sys.getrecursionlimit()

2
Makefile.pre.in
View file

@ -596,7 +596,7 @@ Objects/unicodeobject.o: $(srcdir)/Objects/unicodeobject.c \
$(OPCODETARGETS_H): $(OPCODETARGETGEN_FILES)
$(OPCODETARGETGEN) $(OPCODETARGETS_H)
Python/ceval.o: $(OPCODETARGETS_H)
Python/ceval.o: $(OPCODETARGETS_H) Python/ceval_gil.h
Python/formatter_unicode.o: $(srcdir)/Python/formatter_unicode.c \
$(BYTESTR_DEPS) \

3
Objects/longobject.c
View file

@ -96,10 +96,7 @@ maybe_small_long(PyLongObject *v)
#define MIN(x, y) ((x) > (y) ? (y) : (x))
#define SIGCHECK(PyTryBlock) \
if (--_Py_Ticker < 0) { \
_Py_Ticker = _Py_CheckInterval; \
if (PyErr_CheckSignals()) PyTryBlock \
}
/* forward declaration */
static int bits_in_digit(digit d);

144
Python/ceval.c
View file

@ -216,6 +216,28 @@ PyEval_GetCallStats(PyObject *self)
#endif
#define COMPUTE_EVAL_BREAKER() \
(eval_breaker = gil_drop_request | pendingcalls_to_do | pending_async_exc)
#define SET_GIL_DROP_REQUEST() \
do { gil_drop_request = 1; eval_breaker = 1; } while (0)
#define RESET_GIL_DROP_REQUEST() \
do { gil_drop_request = 0; COMPUTE_EVAL_BREAKER(); } while (0)
#define SIGNAL_PENDING_CALLS() \
do { pendingcalls_to_do = 1; eval_breaker = 1; } while (0)
#define UNSIGNAL_PENDING_CALLS() \
do { pendingcalls_to_do = 0; COMPUTE_EVAL_BREAKER(); } while (0)
#define SIGNAL_ASYNC_EXC() \
do { pending_async_exc = 1; eval_breaker = 1; } while (0)
#define UNSIGNAL_ASYNC_EXC() \
do { pending_async_exc = 0; COMPUTE_EVAL_BREAKER(); } while (0)
#ifdef WITH_THREAD
#ifdef HAVE_ERRNO_H
@ -223,36 +245,55 @@ PyEval_GetCallStats(PyObject *self)
#endif
#include "pythread.h"
static PyThread_type_lock interpreter_lock = 0; /* This is the GIL */
static PyThread_type_lock pending_lock = 0; /* for pending calls */
static long main_thread = 0;
/* This single variable consolidates all requests to break out of the fast path
in the eval loop. */
static volatile int eval_breaker = 0;
/* Request for droppping the GIL */
static volatile int gil_drop_request = 0;
/* Request for running pending calls */
static volatile int pendingcalls_to_do = 0;
/* Request for looking at the `async_exc` field of the current thread state */
static volatile int pending_async_exc = 0;
#include "ceval_gil.h"
int
PyEval_ThreadsInitialized(void)
{
return interpreter_lock != 0;
return gil_created();
}
void
PyEval_InitThreads(void)
{
if (interpreter_lock)
if (gil_created())
return;
interpreter_lock = PyThread_allocate_lock();
PyThread_acquire_lock(interpreter_lock, 1);
create_gil();
take_gil(PyThreadState_GET());
main_thread = PyThread_get_thread_ident();
if (!pending_lock)
pending_lock = PyThread_allocate_lock();
}
void
PyEval_AcquireLock(void)
{
PyThread_acquire_lock(interpreter_lock, 1);
PyThreadState *tstate = PyThreadState_GET();
if (tstate == NULL)
Py_FatalError("PyEval_AcquireLock: current thread state is NULL");
take_gil(tstate);
}
void
PyEval_ReleaseLock(void)
{
PyThread_release_lock(interpreter_lock);
/* This function must succeed when the current thread state is NULL.
We therefore avoid PyThreadState_GET() which dumps a fatal error
in debug mode.
*/
drop_gil(_PyThreadState_Current);
}
void
@ -261,8 +302,8 @@ PyEval_AcquireThread(PyThreadState *tstate)
if (tstate == NULL)
Py_FatalError("PyEval_AcquireThread: NULL new thread state");
/* Check someone has called PyEval_InitThreads() to create the lock */
assert(interpreter_lock);
PyThread_acquire_lock(interpreter_lock, 1);
assert(gil_created());
take_gil(tstate);
if (PyThreadState_Swap(tstate) != NULL)
Py_FatalError(
"PyEval_AcquireThread: non-NULL old thread state");
@ -275,7 +316,7 @@ PyEval_ReleaseThread(PyThreadState *tstate)
Py_FatalError("PyEval_ReleaseThread: NULL thread state");
if (PyThreadState_Swap(NULL) != tstate)
Py_FatalError("PyEval_ReleaseThread: wrong thread state");
PyThread_release_lock(interpreter_lock);
drop_gil(tstate);
}
/* This function is called from PyOS_AfterFork to ensure that newly
@ -287,17 +328,17 @@ void
PyEval_ReInitThreads(void)
{
PyObject *threading, *result;
PyThreadState *tstate;
PyThreadState *tstate = PyThreadState_GET();
if (!interpreter_lock)
if (!gil_created())
return;
/*XXX Can't use PyThread_free_lock here because it does too
much error-checking. Doing this cleanly would require
adding a new function to each thread_*.h. Instead, just
create a new lock and waste a little bit of memory */
interpreter_lock = PyThread_allocate_lock();
recreate_gil();
pending_lock = PyThread_allocate_lock();
PyThread_acquire_lock(interpreter_lock, 1);
take_gil(tstate);
main_thread = PyThread_get_thread_ident();
/* Update the threading module with the new state.
@ -317,7 +358,21 @@ PyEval_ReInitThreads(void)
Py_DECREF(result);
Py_DECREF(threading);
}
#endif
#else
static int eval_breaker = 0;
static int gil_drop_request = 0;
static int pending_async_exc = 0;
#endif /* WITH_THREAD */
/* This function is used to signal that async exceptions are waiting to be
raised, therefore it is also useful in non-threaded builds. */
void
_PyEval_SignalAsyncExc(void)
{
SIGNAL_ASYNC_EXC();
}
/* Functions save_thread and restore_thread are always defined so
dynamically loaded modules needn't be compiled separately for use
@ -330,8 +385,8 @@ PyEval_SaveThread(void)
if (tstate == NULL)
Py_FatalError("PyEval_SaveThread: NULL tstate");
#ifdef WITH_THREAD
if (interpreter_lock)
PyThread_release_lock(interpreter_lock);
if (gil_created())
drop_gil(tstate);
#endif
return tstate;
}
@ -342,9 +397,9 @@ PyEval_RestoreThread(PyThreadState *tstate)
if (tstate == NULL)
Py_FatalError("PyEval_RestoreThread: NULL tstate");
#ifdef WITH_THREAD
if (interpreter_lock) {
if (gil_created()) {
int err = errno;
PyThread_acquire_lock(interpreter_lock, 1);
take_gil(tstate);
errno = err;
}
#endif
@ -390,7 +445,6 @@ static struct {
} pendingcalls[NPENDINGCALLS];
static int pendingfirst = 0;
static int pendinglast = 0;
static volatile int pendingcalls_to_do = 1; /* trigger initialization of lock */
static char pendingbusy = 0;
int
@ -429,8 +483,7 @@ Py_AddPendingCall(int (*func)(void *), void *arg)
pendinglast = j;
}
/* signal main loop */
_Py_Ticker = 0;
pendingcalls_to_do = 1;
SIGNAL_PENDING_CALLS();
if (lock != NULL)
PyThread_release_lock(lock);
return result;
@ -472,7 +525,10 @@ Py_MakePendingCalls(void)
arg = pendingcalls[j].arg;
pendingfirst = (j + 1) % NPENDINGCALLS;
}
pendingcalls_to_do = pendingfirst != pendinglast;
if (pendingfirst != pendinglast)
SIGNAL_PENDING_CALLS();
else
UNSIGNAL_PENDING_CALLS();
PyThread_release_lock(pending_lock);
/* having released the lock, perform the callback */
if (func == NULL)
@ -538,8 +594,7 @@ Py_AddPendingCall(int (*func)(void *), void *arg)
pendingcalls[i].arg = arg;
pendinglast = j;
_Py_Ticker = 0;
pendingcalls_to_do = 1; /* Signal main loop */
SIGNAL_PENDING_CALLS();
busy = 0;
/* XXX End critical section */
return 0;
@ -552,7 +607,7 @@ Py_MakePendingCalls(void)
if (busy)
return 0;
busy = 1;
pendingcalls_to_do = 0;
UNSIGNAL_PENDING_CALLS();
for (;;) {
int i;
int (*func)(void *);
@ -565,7 +620,7 @@ Py_MakePendingCalls(void)
pendingfirst = (i + 1) % NPENDINGCALLS;
if (func(arg) < 0) {
busy = 0;
pendingcalls_to_do = 1; /* We're not done yet */
SIGNAL_PENDING_CALLS(); /* We're not done yet */
return -1;
}
}
@ -658,10 +713,7 @@ static int unpack_iterable(PyObject *, int, int, PyObject **);
fast_next_opcode*/
static int _Py_TracingPossible = 0;
/* for manipulating the thread switch and periodic "stuff" - used to be
per thread, now just a pair o' globals */
int _Py_CheckInterval = 100;
volatile int _Py_Ticker = 0; /* so that we hit a "tick" first thing */
PyObject *
PyEval_EvalCode(PyCodeObject *co, PyObject *globals, PyObject *locals)
@ -791,10 +843,7 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
#define DISPATCH() \
{ \
/* Avoid multiple loads from _Py_Ticker despite `volatile` */ \
int _tick = _Py_Ticker - 1; \
_Py_Ticker = _tick; \
if (_tick >= 0) { \
if (!eval_breaker) { \
FAST_DISPATCH(); \
} \
continue; \
@ -1168,13 +1217,12 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
async I/O handler); see Py_AddPendingCall() and
Py_MakePendingCalls() above. */
if (--_Py_Ticker < 0) {
if (eval_breaker) {
if (*next_instr == SETUP_FINALLY) {
/* Make the last opcode before
a try: finally: block uninterruptable. */
goto fast_next_opcode;
}
_Py_Ticker = _Py_CheckInterval;
tstate->tick_counter++;
#ifdef WITH_TSC
ticked = 1;
@ -1184,40 +1232,32 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
why = WHY_EXCEPTION;
goto on_error;
}
if (pendingcalls_to_do)
/* MakePendingCalls() didn't succeed.
Force early re-execution of this
"periodic" code, possibly after
a thread switch */
_Py_Ticker = 0;
}
if (gil_drop_request) {
#ifdef WITH_THREAD
if (interpreter_lock) {
/* Give another thread a chance */
if (PyThreadState_Swap(NULL) != tstate)
Py_FatalError("ceval: tstate mix-up");
PyThread_release_lock(interpreter_lock);
drop_gil(tstate);
/* Other threads may run now */
PyThread_acquire_lock(interpreter_lock, 1);
take_gil(tstate);
if (PyThreadState_Swap(tstate) != NULL)
Py_FatalError("ceval: orphan tstate");
/* Check for thread interrupts */
#endif
}
/* Check for asynchronous exceptions. */
if (tstate->async_exc != NULL) {
x = tstate->async_exc;
tstate->async_exc = NULL;
UNSIGNAL_ASYNC_EXC();
PyErr_SetNone(x);
Py_DECREF(x);
why = WHY_EXCEPTION;
goto on_error;
}
}
#endif
}
fast_next_opcode:
f->f_lasti = INSTR_OFFSET();

335
Python/ceval_gil.h Normal file
View file

@ -0,0 +1,335 @@
/*
* Implementation of the Global Interpreter Lock (GIL).
*/
#include <stdlib.h>
#include <errno.h>
/* First some general settings */
/* microseconds (the Python API uses seconds, though) */
#define DEFAULT_INTERVAL 5000
static unsigned long gil_interval = DEFAULT_INTERVAL;
#define INTERVAL (gil_interval >= 1 ? gil_interval : 1)
/* Enable if you want to force the switching of threads at least every `gil_interval` */
#undef FORCE_SWITCHING
#define FORCE_SWITCHING
/*
Notes about the implementation:
- The GIL is just a boolean variable (gil_locked) whose access is protected
by a mutex (gil_mutex), and whose changes are signalled by a condition
variable (gil_cond). gil_mutex is taken for short periods of time,
and therefore mostly uncontended.
- In the GIL-holding thread, the main loop (PyEval_EvalFrameEx) must be
able to release the GIL on demand by another thread. A volatile boolean
variable (gil_drop_request) is used for that purpose, which is checked
at every turn of the eval loop. That variable is set after a wait of
`interval` microseconds on `gil_cond` has timed out.
[Actually, another volatile boolean variable (eval_breaker) is used
which ORs several conditions into one. Volatile booleans are
sufficient as inter-thread signalling means since Python is run
on cache-coherent architectures only.]
- A thread wanting to take the GIL will first let pass a given amount of
time (`interval` microseconds) before setting gil_drop_request. This
encourages a defined switching period, but doesn't enforce it since
opcodes can take an arbitrary time to execute.
The `interval` value is available for the user to read and modify
using the Python API `sys.{get,set}switchinterval()`.
- When a thread releases the GIL and gil_drop_request is set, that thread
ensures that another GIL-awaiting thread gets scheduled.
It does so by waiting on a condition variable (switch_cond) until
the value of gil_last_holder is changed to something else than its
own thread state pointer, indicating that another thread was able to
take the GIL.
This is meant to prohibit the latency-adverse behaviour on multi-core
machines where one thread would speculatively release the GIL, but still
run and end up being the first to re-acquire it, making the "timeslices"
much longer than expected.
(Note: this mechanism is enabled with FORCE_SWITCHING above)
*/
#ifndef _POSIX_THREADS
/* This means pthreads are not implemented in libc headers, hence the macro
not present in unistd.h. But they still can be implemented as an external
library (e.g. gnu pth in pthread emulation) */
# ifdef HAVE_PTHREAD_H
# include <pthread.h> /* _POSIX_THREADS */
# endif
#endif
#ifdef _POSIX_THREADS
/*
* POSIX support
*/
#include <pthread.h>
#define ADD_MICROSECONDS(tv, interval) \
do { \
tv.tv_usec += (long) interval; \
tv.tv_sec += tv.tv_usec / 1000000; \
tv.tv_usec %= 1000000; \
} while (0)
/* We assume all modern POSIX systems have gettimeofday() */
#ifdef GETTIMEOFDAY_NO_TZ
#define GETTIMEOFDAY(ptv) gettimeofday(ptv)
#else
#define GETTIMEOFDAY(ptv) gettimeofday(ptv, (struct timezone *)NULL)
#endif
#define MUTEX_T pthread_mutex_t
#define MUTEX_INIT(mut) \
if (pthread_mutex_init(&mut, NULL)) { \
Py_FatalError("pthread_mutex_init(" #mut ") failed"); };
#define MUTEX_LOCK(mut) \
if (pthread_mutex_lock(&mut)) { \
Py_FatalError("pthread_mutex_lock(" #mut ") failed"); };
#define MUTEX_UNLOCK(mut) \
if (pthread_mutex_unlock(&mut)) { \
Py_FatalError("pthread_mutex_unlock(" #mut ") failed"); };
#define COND_T pthread_cond_t
#define COND_INIT(cond) \
if (pthread_cond_init(&cond, NULL)) { \
Py_FatalError("pthread_cond_init(" #cond ") failed"); };
#define COND_PREPARE(cond)
#define COND_SIGNAL(cond) \
if (pthread_cond_signal(&cond)) { \
Py_FatalError("pthread_cond_signal(" #cond ") failed"); };
#define COND_WAIT(cond, mut) \
if (pthread_cond_wait(&cond, &mut)) { \
Py_FatalError("pthread_cond_wait(" #cond ") failed"); };
#define COND_TIMED_WAIT(cond, mut, microseconds, timeout_result) \
{ \
int r; \
struct timespec ts; \
struct timeval deadline; \
\
GETTIMEOFDAY(&deadline); \
ADD_MICROSECONDS(deadline, microseconds); \
ts.tv_sec = deadline.tv_sec; \
ts.tv_nsec = deadline.tv_usec * 1000; \
\
r = pthread_cond_timedwait(&cond, &mut, &ts); \
if (r == ETIMEDOUT) \
timeout_result = 1; \
else if (r) \
Py_FatalError("pthread_cond_timedwait(" #cond ") failed"); \
else \
timeout_result = 0; \
} \
#elif defined(NT_THREADS)
/*
* Windows (2000 and later, as well as (hopefully) CE) support
*/
#include <windows.h>
#define MUTEX_T HANDLE
#define MUTEX_INIT(mut) \
if (!(mut = CreateMutex(NULL, FALSE, NULL))) { \
Py_FatalError("CreateMutex(" #mut ") failed"); };
#define MUTEX_LOCK(mut) \
if (WaitForSingleObject(mut, INFINITE) != WAIT_OBJECT_0) { \
Py_FatalError("WaitForSingleObject(" #mut ") failed"); };
#define MUTEX_UNLOCK(mut) \
if (!ReleaseMutex(mut)) { \
Py_FatalError("ReleaseMutex(" #mut ") failed"); };
/* We emulate condition variables with events. It is sufficient here.
(WaitForMultipleObjects() allows the event to be caught and the mutex
to be taken atomically) */
#define COND_T HANDLE
#define COND_INIT(cond) \
/* auto-reset, non-signalled */ \
if (!(cond = CreateEvent(NULL, FALSE, FALSE, NULL))) { \
Py_FatalError("CreateMutex(" #cond ") failed"); };
#define COND_PREPARE(cond) \
if (!ResetEvent(cond)) { \
Py_FatalError("ResetEvent(" #cond ") failed"); };
#define COND_SIGNAL(cond) \
if (!SetEvent(cond)) { \
Py_FatalError("SetEvent(" #cond ") failed"); };
#define COND_WAIT(cond, mut) \
{ \
DWORD r; \
HANDLE objects[2] = { cond, mut }; \
MUTEX_UNLOCK(mut); \
r = WaitForMultipleObjects(2, objects, TRUE, INFINITE); \
if (r != WAIT_OBJECT_0) \
Py_FatalError("WaitForSingleObject(" #cond ") failed"); \
}
#define COND_TIMED_WAIT(cond, mut, microseconds, timeout_result) \
{ \
DWORD r; \
HANDLE objects[2] = { cond, mut }; \
MUTEX_UNLOCK(mut); \
r = WaitForMultipleObjects(2, objects, TRUE, microseconds / 1000); \
if (r == WAIT_TIMEOUT) { \
MUTEX_LOCK(mut); \
timeout_result = 1; \
} \
else if (r != WAIT_OBJECT_0) \
Py_FatalError("WaitForSingleObject(" #cond ") failed"); \
else \
timeout_result = 0; \
}
#else
#error You need either a POSIX-compatible or a Windows system!
#endif /* _POSIX_THREADS, NT_THREADS */
/* Whether the GIL is already taken (-1 if uninitialized). This is volatile
because it can be read without any lock taken in ceval.c. */
static volatile int gil_locked = -1;
/* Number of GIL switches since the beginning. */
static unsigned long gil_switch_number = 0;
/* Last thread holding / having held the GIL. This helps us know whether
anyone else was scheduled after we dropped the GIL. */
static PyThreadState *gil_last_holder = NULL;
/* This condition variable allows one or several threads to wait until
the GIL is released. In addition, the mutex also protects the above
variables. */
static COND_T gil_cond;
static MUTEX_T gil_mutex;
#ifdef FORCE_SWITCHING
/* This condition variable helps the GIL-releasing thread wait for
a GIL-awaiting thread to be scheduled and take the GIL. */
static COND_T switch_cond;
static MUTEX_T switch_mutex;
#endif
static int gil_created(void)
{
return gil_locked >= 0;
}
static void create_gil(void)
{
MUTEX_INIT(gil_mutex);
#ifdef FORCE_SWITCHING
MUTEX_INIT(switch_mutex);
#endif
COND_INIT(gil_cond);
#ifdef FORCE_SWITCHING
COND_INIT(switch_cond);
#endif
gil_locked = 0;
gil_last_holder = NULL;
}
static void recreate_gil(void)
{
create_gil();
}
static void drop_gil(PyThreadState *tstate)
{
/* NOTE: tstate is allowed to be NULL. */
if (!gil_locked)
Py_FatalError("drop_gil: GIL is not locked");
if (tstate != NULL && tstate != gil_last_holder)
Py_FatalError("drop_gil: wrong thread state");
MUTEX_LOCK(gil_mutex);
gil_locked = 0;
COND_SIGNAL(gil_cond);
#ifdef FORCE_SWITCHING
COND_PREPARE(switch_cond);
#endif
MUTEX_UNLOCK(gil_mutex);
#ifdef FORCE_SWITCHING
if (gil_drop_request) {
MUTEX_LOCK(switch_mutex);
/* Not switched yet => wait */
if (gil_last_holder == tstate)
COND_WAIT(switch_cond, switch_mutex);
MUTEX_UNLOCK(switch_mutex);
}
#endif
}
static void take_gil(PyThreadState *tstate)
{
int err;
if (tstate == NULL)
Py_FatalError("take_gil: NULL tstate");
err = errno;
MUTEX_LOCK(gil_mutex);
if (!gil_locked)
goto _ready;
COND_PREPARE(gil_cond);
while (gil_locked) {
int timed_out = 0;
unsigned long saved_switchnum;
saved_switchnum = gil_switch_number;
COND_TIMED_WAIT(gil_cond, gil_mutex, INTERVAL, timed_out);
/* If we timed out and no switch occurred in the meantime, it is time
to ask the GIL-holding thread to drop it. */
if (timed_out && gil_locked && gil_switch_number == saved_switchnum) {
SET_GIL_DROP_REQUEST();
}
}
_ready:
#ifdef FORCE_SWITCHING
/* This mutex must be taken before modifying gil_last_holder (see drop_gil()). */
MUTEX_LOCK(switch_mutex);
#endif
/* We now hold the GIL */
gil_locked = 1;
if (tstate != gil_last_holder) {
gil_last_holder = tstate;
++gil_switch_number;
}
#ifdef FORCE_SWITCHING
COND_SIGNAL(switch_cond);
MUTEX_UNLOCK(switch_mutex);
#endif
if (gil_drop_request) {
RESET_GIL_DROP_REQUEST();
}
if (tstate->async_exc != NULL) {
_PyEval_SignalAsyncExc();
}
MUTEX_UNLOCK(gil_mutex);
errno = err;
}
void _PyEval_SetSwitchInterval(unsigned long microseconds)
{
gil_interval = microseconds;
}
unsigned long _PyEval_GetSwitchInterval()
{
return gil_interval;
}

1
Python/pystate.c
View file

@ -434,6 +434,7 @@ PyThreadState_SetAsyncExc(long id, PyObject *exc) {
p->async_exc = exc;
HEAD_UNLOCK();
Py_XDECREF(old_exc);
_PyEval_SignalAsyncExc();
return 1;
}
}

64
Python/sysmodule.c
View file

@ -448,10 +448,18 @@ Return the profiling function set with sys.setprofile.\n\
See the profiler chapter in the library manual."
);
/* TODO: deprecate */
static int _check_interval = 100;
static PyObject *
sys_setcheckinterval(PyObject *self, PyObject *args)
{
if (!PyArg_ParseTuple(args, "i:setcheckinterval", &_Py_CheckInterval))
if (PyErr_WarnEx(PyExc_DeprecationWarning,
"sys.getcheckinterval() and sys.setcheckinterval() "
"are deprecated. Use sys.setswitchinterval() "
"instead.", 1) < 0)
return NULL;
if (!PyArg_ParseTuple(args, "i:setcheckinterval", &_check_interval))
return NULL;
Py_INCREF(Py_None);
return Py_None;
@ -467,13 +475,59 @@ n instructions. This also affects how often thread switches occur."
static PyObject *
sys_getcheckinterval(PyObject *self, PyObject *args)
{
return PyLong_FromLong(_Py_CheckInterval);
if (PyErr_WarnEx(PyExc_DeprecationWarning,
"sys.getcheckinterval() and sys.setcheckinterval() "
"are deprecated. Use sys.getswitchinterval() "
"instead.", 1) < 0)
return NULL;
return PyLong_FromLong(_check_interval);
}
PyDoc_STRVAR(getcheckinterval_doc,
"getcheckinterval() -> current check interval; see setcheckinterval()."
);
#ifdef WITH_THREAD
static PyObject *
sys_setswitchinterval(PyObject *self, PyObject *args)
{
double d;
if (!PyArg_ParseTuple(args, "d:setswitchinterval", &d))
return NULL;
if (d <= 0.0) {
PyErr_SetString(PyExc_ValueError,
"switch interval must be strictly positive");
return NULL;
}
_PyEval_SetSwitchInterval((unsigned long) (1e6 * d));
Py_INCREF(Py_None);
return Py_None;
}
PyDoc_STRVAR(setswitchinterval_doc,
"setswitchinterval(n)\n\
\n\
Set the ideal thread switching delay inside the Python interpreter\n\
The actual frequency of switching threads can be lower if the\n\
interpreter executes long sequences of uninterruptible code\n\
(this is implementation-specific and workload-dependent).\n\
\n\
The parameter must represent the desired switching delay in seconds\n\
A typical value is 0.005 (5 milliseconds)."
);
static PyObject *
sys_getswitchinterval(PyObject *self, PyObject *args)
{
return PyFloat_FromDouble(1e-6 * _PyEval_GetSwitchInterval());
}
PyDoc_STRVAR(getswitchinterval_doc,
"getswitchinterval() -> current thread switch interval; see setswitchinterval()."
);
#endif /* WITH_THREAD */
#ifdef WITH_TSC
static PyObject *
sys_settscdump(PyObject *self, PyObject *args)
@ -895,6 +949,12 @@ static PyMethodDef sys_methods[] = {
setcheckinterval_doc},
{"getcheckinterval", sys_getcheckinterval, METH_NOARGS,
getcheckinterval_doc},
#ifdef WITH_THREAD
{"setswitchinterval", sys_setswitchinterval, METH_VARARGS,
setswitchinterval_doc},
{"getswitchinterval", sys_getswitchinterval, METH_NOARGS,
getswitchinterval_doc},
#endif
#ifdef HAVE_DLOPEN
{"setdlopenflags", sys_setdlopenflags, METH_VARARGS,
setdlopenflags_doc},