Is this saying that this program won’t ever finish? Yes, that program won’t finish, just try it out. I ask because I have a situation where in my main thread I’m calling sys.exit(), and the process just hangs and my other threads are running as I can see the log. Does this have anything to … Read more
I did some speed tests as well, the time to set the flag and for action to be taken is pleasantly fast 0.00002 secs on a slow 2 processor Linux box. Example of thread pause test using set() and clear() events: import threading import time # This function gets called by our thread.. so it … Read more
Since there are often questions about using QThread in PyQt, similar to yours, here is an example that shows how to correctly use threads in PyQt. I’m hoping it can be useful as a goto-answer for similar questions so I spent a bit more time than usual preparing this. The example creates a number of … Read more
The http.client.HTTPResponse-object you get back from urlopen() has a _io.BufferedReader-object attached, and this object cannot be pickled. pickle.dumps(urllib.request.urlopen(‘http://www.python.org’).fp) Traceback (most recent call last): … pickle.dumps(urllib.request.urlopen(‘http://www.python.org’).fp) TypeError: cannot serialize ‘_io.BufferedReader’ object multiprocessing.Pool will need to pickle (serialize) the results to send it back to the parent process and this fails here. Since dummy uses threads instead … Read more
The args kwarg of threading.Thread expects an iterable, and each element in that iterable is being passed to the target function. Since you are providing a string for args: t = threading.Thread(target=startSuggestworker, args=(start_keyword)) each character is being passed as a separate argument to startSuggestworker. Instead, you should provide args a tuple: t = threading.Thread(target=startSuggestworker, args=(start_keyword,)) … Read more
You would call the cancel method after you start the timer: import time import threading def hello(): print “hello, world” time.sleep(2) t = threading.Timer(3.0, hello) t.start() var=”something” if var == ‘something’: t.cancel() You might consider using a while-loop on a Thread, instead of using a Timer. Here is an example appropriated from Nikolaus Gradwohl’s answer … Read more
The solution is to write to the file in one thread only. import Queue # or queue in Python 3 import threading class PrintThread(threading.Thread): def __init__(self, queue): threading.Thread.__init__(self) self.queue = queue def printfiles(self, p): for path, dirs, files in os.walk(p): for f in files: print(f, file=output) def run(self): while True: result = self.queue.get() self.printfiles(result) self.queue.task_done() … Read more
This calls the function and passes its result as target: threading.Thread(target=DoWorkItem(), args=()) Lose the parentheses to pass the function object itself: threading.Thread(target=DoWorkItem, args=())
In Python 3, thread has been renamed to _thread. It is infrastructure code that is used to implement threading, and normal Python code shouldn’t be going anywhere near it. _thread exposes a fairly raw view of the underlying OS level processes. This is almost never what you want, hence the rename in Py3k to indicate … Read more
First, in Python, if your code is CPU-bound, multithreading won’t help, because only one thread can hold the Global Interpreter Lock, and therefore run Python code, at a time. So, you need to use processes, not threads. This is not true if your operation “takes forever to return” because it’s IO-bound—that is, waiting on the … Read more