how can i dynamically change the value of lis so that every second it’ll output a list in which the last element is 2x the last element of the previous list . i need the output to be something like this but right now the output is I tried using global lis but that didnt work either. Answer You can
Tag: python-multiprocessing
Sharing instance of proxy object across processes results in pickle errors
I’m trying to implement a simple shared object system in python between several processes. I’m doing the following: However on Python 3.9, this keeps failing for various pickle errors, like _pickle.UnpicklingError: invalid load key, ‘x0a’. Am I doing something incorrect here? AFAIK it …
Atomic Code in gunicorn multiprocessing / only run code in worker 1?
I am new to gunicorn multiprocessing (by calling gunicorn –worker=X). I am using it with Flask to provide the WSGI implementation for our productive frontend. To use multiprocessing, we pass the above mentioned parameter to unicorn. Our Flask application also uses APScheduler (via Flask-APScheduler) to …
Multiprocessing where new process starts hafway through other process
I have a Python script that does two things; 1) it downloads a large file by making an API call, and 2) preprocess that large file. I want to use Multiprocessing to run my script. Each individual part (1 and 2) takes quite long. Everything happens in-memory due to the large size of the files, so ideally a sin…
Keep indefinite connections open on TCP server with asyncio streams?
I’m trying to understand how to use asyncio streams for multiple connections that will keep sending messages until a predefined condition or a socket timeout. Looking at Python docs, they provide the following example for a TCP server based on asyncio streams: What I’m trying to do is more complex…
multiprocessing subprocess log to separate file
My main program logs to its own log file and the sub-process should have its own log file. I replaced the logger object inside the multiprocessing process, but the logging data from the sub-process is additionally redirected to the main log file. How can I prevent this? The structure looks like this: Answer I…
How to use pyarrow parquet with multiprocessing
I want to read multiple hdfs files simultaneously using pyarrow and multiprocessing. The simple python script works (see below), but if I try to do the same thing with multiprocessing, then it hangs indefinitely. My only guess is that env is different somehow, but all the environment variable should be the sa…
Add unknown number of jobs to pool until a job returns None
Assume that we want to send a lot of web requests, and do something with the data that we get back. The data crunching that we have to do on the response is quite heavy, so we’d want to parallelize this: a main process distributes query URLs to child processes, which then fetch the data and do some proc…
Python: will a thread ever unblock while hanging on a `Queue.get(block=True)` call if the queue is suddenly destroyed from another thread/process?
TLDR: Would a blocking get be unblocked by a queue that would be terminated in some way? Long question: Okay, so I know that the thread will hang if the queue (multiprocessing.Queue) remains empty forever while trying to fetch something from it with a blocking get. But suppose now that in another thread or pr…
Pickle/unpickle only once per worker
I am using python multiprocessing module to spread say 10000 steps of a given task on 4 workers using a Pool. The task that is sent on the workers is a method of a complex object. If I understand right the documentation, pickle is used to dump and load the object at each step which means 10000 pickling/unpick…