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author | Richard Purdie <richard.purdie@linuxfoundation.org> | 2022-03-29 15:17:10 +0100 |
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committer | Richard Purdie <richard.purdie@linuxfoundation.org> | 2022-03-30 13:05:03 +0100 |
commit | 928bcb10a46939eaf801bea0b633e4624b5b5dfa (patch) | |
tree | 42f3bc730e5fd7f4306d7b090574e30343c85cee /bitbake/lib/bb/server/process.py | |
parent | c0ff6c75eedea6e0f472b45456aed238073ac157 (diff) | |
download | poky-928bcb10a46939eaf801bea0b633e4624b5b5dfa.tar.gz |
bitbake: cooker/process: Fix signal handling lockups
If a parser process is terminated while holding a write lock, then it
will lead to a deadlock (see
https://docs.python.org/3/library/multiprocessing.html#multiprocessing.Process.terminate).
With SIGTERM, we don't want to terminate holding the lock. We also don't
want a SIGINT to cause a partial write to the event stream.
I tried using signal masks to avoid this but it doesn't work, see
https://bugs.python.org/issue47139
Instead, add a signal handler and catch the calls around the critical section.
We also need a thread lock to ensure other threads in the same process don't
handle the signal until all the threads are not in the lock.
(Bitbake rev: a40efaa5556a188dfe46c8d060adde37dc400dcd)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'bitbake/lib/bb/server/process.py')
-rw-r--r-- | bitbake/lib/bb/server/process.py | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/bitbake/lib/bb/server/process.py b/bitbake/lib/bb/server/process.py index 7c587a9110..ce53fdc678 100644 --- a/bitbake/lib/bb/server/process.py +++ b/bitbake/lib/bb/server/process.py | |||
@@ -20,6 +20,7 @@ import os | |||
20 | import sys | 20 | import sys |
21 | import time | 21 | import time |
22 | import select | 22 | import select |
23 | import signal | ||
23 | import socket | 24 | import socket |
24 | import subprocess | 25 | import subprocess |
25 | import errno | 26 | import errno |
@@ -737,11 +738,28 @@ class ConnectionWriter(object): | |||
737 | # Why bb.event needs this I have no idea | 738 | # Why bb.event needs this I have no idea |
738 | self.event = self | 739 | self.event = self |
739 | 740 | ||
740 | def send(self, obj): | 741 | def _send(self, obj): |
741 | obj = multiprocessing.reduction.ForkingPickler.dumps(obj) | ||
742 | with self.wlock: | 742 | with self.wlock: |
743 | self.writer.send_bytes(obj) | 743 | self.writer.send_bytes(obj) |
744 | 744 | ||
745 | def send(self, obj): | ||
746 | obj = multiprocessing.reduction.ForkingPickler.dumps(obj) | ||
747 | # See notes/code in CookerParser | ||
748 | # We must not terminate holding this lock else processes will hang. | ||
749 | # For SIGTERM, raising afterwards avoids this. | ||
750 | # For SIGINT, we don't want to have written partial data to the pipe. | ||
751 | # pthread_sigmask block/unblock would be nice but doesn't work, https://bugs.python.org/issue47139 | ||
752 | process = multiprocessing.current_process() | ||
753 | if process and hasattr(process, "queue_signals"): | ||
754 | with process.signal_threadlock: | ||
755 | process.queue_signals = True | ||
756 | self._send(obj) | ||
757 | process.queue_signals = False | ||
758 | for sig in process.signal_received.pop(): | ||
759 | process.handle_sig(sig, None) | ||
760 | else: | ||
761 | self._send(obj) | ||
762 | |||
745 | def fileno(self): | 763 | def fileno(self): |
746 | return self.writer.fileno() | 764 | return self.writer.fileno() |
747 | 765 | ||