| @@ -244,6 +244,32 @@ trip_signal(int sig_num) |
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Handlers[sig_num].tripped = 1; |
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+if (!is_tripped) { |
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+/* Set is_tripped after setting .tripped, as it gets |
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+ cleared in PyErr_CheckSignals() before .tripped. */ |
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+is_tripped = 1; |
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+Py_AddPendingCall(checksignals_witharg, NULL); |
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+ } |
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+ |
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+/* And then write to the wakeup fd *after* setting all the globals and |
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+ doing the Py_AddPendingCall. We used to write to the wakeup fd and then |
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+ set the flag, but this allowed the following sequence of events |
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+ (especially on windows, where trip_signal runs in a new thread): |
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+ |
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+ - main thread blocks on select([wakeup_fd], ...) |
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+ - signal arrives |
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+ - trip_signal writes to the wakeup fd |
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+ - the main thread wakes up |
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+ - the main thread checks the signal flags, sees that they're unset |
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+ - the main thread empties the wakeup fd |
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+ - the main thread goes back to sleep |
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+ - trip_signal sets the flags to request the Python-level signal handler |
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+ be run |
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+ - the main thread doesn't notice, because it's asleep |
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+ |
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+ See bpo-30038 for more details. |
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+ */ |
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+ |
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#ifdef MS_WINDOWS |
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fd = Py_SAFE_DOWNCAST(wakeup.fd, SOCKET_T, int); |
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#else |
| @@ -281,13 +307,6 @@ trip_signal(int sig_num) |
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} |
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} |
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} |
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- |
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-if (!is_tripped) { |
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-/* Set is_tripped after setting .tripped, as it gets |
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- cleared in PyErr_CheckSignals() before .tripped. */ |
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-is_tripped = 1; |
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-Py_AddPendingCall(checksignals_witharg, NULL); |
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- } |
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} |
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static void |