> 2024年2月22日 上午1:55，Ilya Maximets <i.maxim...@ovn.org> 写道：
>
> On 2/21/24 15:27, Aaron Conole wrote:
>> Daniel Ding <danieldin...@gmail.com> writes:
>>
>>> After running ovs-tcpdump and inputs multiple CTRL+C, the program will
>>> raise the following exception.
>>>
>>> Error in atexit._run_exitfuncs:
>>> Traceback (most recent call last):
>>> File "/usr/bin/ovs-tcpdump", line 421, in cleanup_mirror
>>> ovsdb = OVSDB(db_sock)
>>> File "/usr/bin/ovs-tcpdump", line 168, in __init__
>>> OVSDB.wait_for_db_change(self._idl_conn) # Initial Sync with DB
>>> File "/usr/bin/ovs-tcpdump", line 155, in wait_for_db_change
>>> while idl.change_seqno == seq and not idl.run():
>>>
>>> Signed-off-by: Daniel Ding <zhihui.d...@easystack.cn>
>>> ---
>>
>> LGTM for the linux side - maybe Alin might check the windows side.
>
> The code is copied from the fatal-signla library, so it is likely fine.
> However, I don;t think this issue should be fixed on the application
> level (ovs-tcpdump). There seems to be adifference in how C and python
> fatal-signla libraries behave. The C version calls the hooks in the run()
> function and the signal handler only updates the signal number variable.
> So, if the same signal arrives multiple times it will be handled only once
> and the run() function will not exit until all the hooks are done, unless
> it is a segfault.
>
> With python implementation we're calling hooks right from the signal
> handler (it's not a real signal handler, so we're allowed to use not
> really singal-safe functions there). So, if another signal arrives while
> we're executing the hooks, the second hook execution will be skipped
> due to 'recursion' check, but the signal will be re-raised immediately,
> killing the process.
As your suggestions, I rewrite recurse as a threading.Lock. So that protect
calling hooks
applications registered.
>
> There is likley a way to fix that by using a mutex instead of recursion
> check and blocking it while executing the hooks. The signal number
> will need to be stored in the signal handler and the signal will need
> to be re-raised in the call_hooks() instead of signal handler.
> We can use mutex.acquire(blocking=False) as a way to prevent recursion.
>
To avoid breaking calling hooks, I set the signal restored in the signal
handler to SIG_IGN in
call_hooks. And move re-raised the signal in the call_hooks with locked.
> Does that make sense?
>
> Best regards, Ilya Maximets.
diff --git a/python/ovs/fatal_signal.py b/python/ovs/fatal_signal.py
index cb2e99e87..3aa56a166 100644
--- a/python/ovs/fatal_signal.py
+++ b/python/ovs/fatal_signal.py
@@ -16,6 +16,7 @@ import atexit
import os
import signal
import sys
+import threading
import ovs.vlog
@@ -112,28 +113,34 @@ def _unlink(file_):
def _signal_handler(signr, _):
_call_hooks(signr)
- # Re-raise the signal with the default handling so that the program
- # termination status reflects that we were killed by this signal.
- signal.signal(signr, signal.SIG_DFL)
- os.kill(os.getpid(), signr)
-
def _atexit_handler():
_call_hooks(0)
-recurse = False
+recurse = threading.Lock()
def _call_hooks(signr):
global recurse
- if recurse:
+ if recurse.locked():
return
- recurse = True
- for hook, cancel, run_at_exit in _hooks:
- if signr != 0 or run_at_exit:
- hook()
+ with recurse:
+ if signr != 0:
+ signal.signal(signr, signal.SIG_IGN)
+ else:
+ signal.signal(signal.SIGINT, signal.SIG_IGN)
+
+ for hook, cancel, run_at_exit in _hooks:
+ if signr != 0 or run_at_exit:
+ hook()
+
+ if signr != 0:
+ # Re-raise the signal with the default handling so that the program
+ # termination status reflects that we were killed by this signal.
+ signal.signal(signr, signal.SIG_DFL)
+ os.kill(os.getpid(), signr)
_inited = False
@@ -165,7 +172,6 @@ def signal_alarm(timeout):
if sys.platform == "win32":
import time
- import threading
class Alarm (threading.Thread):
def __init__(self, timeout):
--
2.43.0
Thanks Ilya Maximets, please help me review again.
Best regards, Daniel Ding.
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