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gh-84570: Send-Wait Fixes for _xxinterpchannels #111006

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Merged
ericsnowcurrently merged 10 commits into from
Oct 17, 2023
Merged

gh-84570: Send-Wait Fixes for _xxinterpchannels #111006

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1d417f7
Expose PyThread_acquire_lock_timed_with_retries().
ericsnowcurrently Sep 18, 2023
0d2769a
Use PyThread_acquire_lock_timed_with_retries().
ericsnowcurrently Sep 18, 2023
202f700
Free the lock.
ericsnowcurrently Oct 16, 2023
38bf6a1
Add _channelitem.received.
ericsnowcurrently Oct 16, 2023
fff6708
Revert "Add _channelitem.received."
ericsnowcurrently Oct 16, 2023
f904a52
Stop waiting when the channel is closed.
ericsnowcurrently Oct 10, 2023
419ed33
Clean up (incl. clear the sent item if waiting failed).
ericsnowcurrently Oct 17, 2023
09fccc6
Add basic tests for send-wait.
ericsnowcurrently Oct 17, 2023
7fcf8fe
Skip a test under refleak runs.
ericsnowcurrently Oct 17, 2023
ab148fa
Handle a small race with waiting->status when releasing.
ericsnowcurrently Oct 17, 2023
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Handle a small race with waiting->status when releasing.
  • Loading branch information
@ericsnowcurrently
ericsnowcurrently committed Oct 17, 2023
commit ab148fae9e3a21b6aec00a2823d3464796bbaff9
39 changes: 32 additions & 7 deletions Modules/_xxinterpchannelsmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,13 @@
#include "pycore_pybuffer.h" // _PyBuffer_ReleaseInInterpreterAndRawFree()
#include "pycore_interp.h" // _PyInterpreterState_LookUpID()

#ifdef MS_WINDOWS
#define WIN32_LEAN_AND_MEAN
#include <windows.h> // SwitchToThread()
#elif defined(HAVE_SCHED_H)
#include <sched.h> // sched_yield()
#endif


/*
This module has the following process-global state:
Expand Down Expand Up @@ -596,7 +603,8 @@ typedef struct wait_info {
enum {
WAITING_NO_STATUS = 0,
WAITING_ACQUIRED = 1,
WAITING_RELEASED = 2,
WAITING_RELEASING = 2,
WAITING_RELEASED = 3,
} status;
int received;
_channelitem_id_t itemid;
Expand All @@ -621,7 +629,8 @@ _waiting_init(_waiting_t *waiting)
static void
_waiting_clear(_waiting_t *waiting)
{
assert(waiting->status != WAITING_ACQUIRED);
assert(waiting->status != WAITING_ACQUIRED
&& waiting->status != WAITING_RELEASING);
if (waiting->mutex != NULL) {
PyThread_free_lock(waiting->mutex);
waiting->mutex = NULL;
Expand Down Expand Up @@ -649,12 +658,25 @@ _waiting_release(_waiting_t *waiting, int received)
assert(waiting->status == WAITING_ACQUIRED);
assert(!waiting->received);

waiting->status = WAITING_RELEASING;
PyThread_release_lock(waiting->mutex);
waiting->status = WAITING_RELEASED;
if (waiting->received != received) {
assert(received == 1);
waiting->received = received;
}
waiting->status = WAITING_RELEASED;
}

static void
_waiting_finish_releasing(_waiting_t *waiting)
{
while (waiting->status == WAITING_RELEASING) {
#ifdef MS_WINDOWS
SwitchToThread();
#elif defined(HAVE_SCHED_H)
sched_yield();
#endif
}
}

struct _channelitem;
Expand Down Expand Up @@ -1881,6 +1903,7 @@ _channel_send_wait(_channels *channels, int64_t cid, PyObject *obj)
/* Wait until the object is received. */
if (wait_for_lock(waiting.mutex) < 0) {
assert(PyErr_Occurred());
_waiting_finish_releasing(&waiting);
/* The send() call is failing now, so make sure the item
won't be received. */
_channel_clear_sent(channels, cid, &waiting);
Expand All @@ -1892,14 +1915,16 @@ _channel_send_wait(_channels *channels, int64_t cid, PyObject *obj)
// XXX Emit a warning if not a TimeoutError?
PyErr_Clear();
}
else if (!waiting.received) {
else {
_waiting_finish_releasing(&waiting);
assert(waiting.status == WAITING_RELEASED);
res = ERR_CHANNEL_CLOSED_WAITING;
goto finally;
if (!waiting.received) {
res = ERR_CHANNEL_CLOSED_WAITING;
goto finally;
}
}

/* success! */
assert(waiting.status == WAITING_RELEASED);
res = 0;

finally:
Expand Down