On Dec 28 2008, 6:33 pm, "Giampaolo Rodola'" <gne...@gmail.com> wrote:
> Hi,
> I know that it's not possible to "kill" threads but I'm wondering if
> does exist some workaround for my problem.
> I have a test suite which does a massive usage of threads.
> Sometimes happens that one test fails, the test suite keeps running
> until the end, and when it's finished the program hangs on and the
> only way to stop is to kill it manually.
> I noticed that, at the end of the program, I can call
> threading.enumerate() and see the pending thread objects:
>
Hi,
The way I handle it is to make sure that after each test, the thread
count has returned to what I expect.
It is possible to kill a thread if it's not blocked on a system call.
It's highly unrecommended for standard usage but your use case exactly
the one where the ability to kill a thread is very useful.
I use the following code, which I borrowed to the Python Cook book
somewhere:
def _async_raise(tid, exctype):
'''Raises an exception in the threads with id tid'''
if not inspect.isclass(exctype):
raise TypeError("Only types can be raised (not instances)")
res = ctypes.pythonapi.PyThreadState_SetAsyncExc(tid,
ctypes.py_object(exctype))
if res == 0:
raise ValueError("invalid thread id")
elif res != 1:
# """if it returns a number greater than one, you're in
trouble,
# and you should call it again with exc=NULL to revert the
effect"""
ctypes.pythonapi.PyThreadState_SetAsyncExc(tid, 0)
raise SystemError("PyThreadState_SetAsyncExc failed")
class ThreadWithExc(threading.Thread):
'''A thread class that supports raising exception in the thread
from another thread.
'''
def _get_my_tid(self):
"""determines this (self's) thread id
CAREFUL : this function is executed in the context of the
caller thread,
to get the identity of the thread represented by this
instance.
"""
if not self.isAlive():
raise threading.ThreadError("the thread is not active")
# do we have it cached?
if hasattr(self, "_thread_id"):
return self._thread_id
# no, look for it in the _active dict
for tid, tobj in threading._active.items():
if tobj is self:
self._thread_id = tid
return tid
# TODO : in python 2.6, there's a simpler way to do :
self.ident ...
raise AssertionError("could not determine the thread's id")
def raiseExc(self, exctype):
"""Raises the given exception type in the context of this
thread.
If the thread is busy in a system call (time.sleep(),
socket.accept(), ...) the exception
is simply ignored.
If you are sure that your exception should terminate the
thread, one way to ensure that
it works is:
t = ThreadWithExc( ... )
...
t.raiseExc( SomeException )
while t.isAlive():
time.sleep( 0.1 )
t.raiseExc( SomeException )
If the exception is to be caught by the thread, you need a way
to check that your
thread has caught it.
CAREFUL : this function is executed in the context of the
caller thread,
to raise an excpetion in the context of the thread represented
by this instance.
"""
_async_raise( self._get_my_tid(), exctype )
cheers,
Philippe
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