I have a file to download (download path extracted from json. eg: http://testsite/abc.zip). I need a help to perform, all the 5 threads should download the abc.zip file to the output directory and the download has to be Asynchronous or concurrent. Currently with the below code it does download the file 5 time…
Tag: multithreading
What kind of problems (if any) would there be combining asyncio with multiprocessing?
As almost everyone is aware when they first look at threading in Python, there is the GIL that makes life miserable for people who actually want to do processing in parallel – or at least give it a chance. I am currently looking at implementing something like the Reactor pattern. Effectively I want to l…
What is the use of join() in threading?
I was studying the python threading and came across join(). The author told that if thread is in daemon mode then i need to use join() so that thread can finish itself before main thread terminates. but I have also seen him using t.join() even though t was not daemon example code is this i don’t know wh…
threading.Timer – repeat function every ‘n’ seconds
I want to fire off a function every 0.5 seconds and be able to start and stop and reset the timer. I’m not too knowledgeable of how Python threads work and am having difficulties with the python timer. However, I keep getting RuntimeError: threads can only be started once when I execute threading.timer.…
Python – appending to same file from multiple threads
I’m writing an app that appends lines to the same file from multiple threads. I have a problem in which some lines are appended without a new line. Any solution for this? Answer The solution is to write to the file in one thread only.
How to use multiprocessing queue in Python?
I’m having much trouble trying to understand just how the multiprocessing queue works on python and how to implement it. Lets say I have two python modules that access data from a shared file, let’s call these two modules a writer and a reader. My plan is to have both the reader and writer put req…
Pausing two Python threads while a third one does stuff (with locks?)
I’m new to concurrent programming. I’d like to execute three tasks repeatedly. The first two should run all the time, the third should run every hour or so. The first two tasks can run in parallel, but I always want to pause them while the third task is running. Here’s the skeleton of what I…
background function in Python
I’ve got a Python script that sometimes displays images to the user. The images can, at times, be quite large, and they are reused often. Displaying them is not critical, but displaying the message associated with them is. I’ve got a function that downloads the image needed and saves it locally. R…
How to get the return value from a thread?
The function foo below returns a string ‘foo’. How can I get the value ‘foo’ which is returned from the thread’s target? The “one obvious way to do it”, shown above, doesn’t work: thread.join() returned None. Answer In Python 3.2+, stdlib concurrent.futures modu…
How to get the number of active threads started by specific class?
code looks like below: Is there a way to get the number of threads being active by originating class ? Answer This is a minor modification of Doug Hellman’s multiprocessing ActivePool example code (to use threading). The idea is to have your workers register themselves in a pool, unregister themselves w…