From https://docs.docker.com/get-started – “Fundamentally, a container is nothing but a running process, with some added encapsulation features applied to it in order to keep it isolated from the host and from other containers.” Docker runs on a host machine. That host machine (or virtual machine) has a certain number of physical (or virtual) CPU’s. The … Read more
One solution that I found (although it might not be the most “elegant” solution is using conn.poll. (documentation) Poll returns True if the Listener has new data, and (most importantly) is nonblocking if no argument is passed to it. I’m not 100% sure that this is the best way to do this, but I’ve had … Read more
Prerequisite In Python (in the following I use 64-bit build of Python 3.6.5) everything is an object. This has its overhead and with getsizeof we can see exactly the size of an object in bytes: >>> import sys >>> sys.getsizeof(42) 28 >>> sys.getsizeof(‘T’) 50 When fork system call used (default on *nix, see multiprocessing.get_start_method()) to … Read more
Use a shared variable to communicate. For example, like this, Example Code: import multiprocessing def worker(procnum, return_dict): “””worker function””” print(str(procnum) + ” represent!”) return_dict[procnum] = procnum if __name__ == “__main__”: manager = multiprocessing.Manager() return_dict = manager.dict() jobs = [] for i in range(5): p = multiprocessing.Process(target=worker, args=(i, return_dict)) jobs.append(p) p.start() for proc in jobs: proc.join() … Read more
As Matino correctly explained: logging in a multiprocessing setup is not safe, as multiple processes (who do not know anything about the other ones existing) are writing into the same file, potentially intervening with each other. Now what happens is that every process holds an open file handle and does an “append write” into that … Read more
I know the topic is quite old now, but as it still appears as the first answer when typing ‘multiprocessing logical core’ in google… I feel like I have to give an additional answer because I can see that it would be possible for people in 2018 (or even later..) to get easily confused here … Read more
The problem is not with the code / Python 3.6, it is with Spyder. After some investigation I found that the code runs fine when executed in an external system terminal but not when run in Spyder’s IPython console. I was able to dump the contents of spec and assign them to a variable that … Read more
multiprocessing.Lock is implemented using a Semaphore object provided by the OS. On Linux, the child just inherits a handle to the Semaphore from the parent via os.fork. This isn’t a copy of the semaphore; it’s actually inheriting the same handle the parent has, the same way file descriptors can be inherited. Windows on the other … Read more
From my experience – the problem lies in loading Keras to one process and then spawning a new process when the keras has been loaded to your main environment. But for some applications (like e.g. training a mixture of Kerasmodels) it’s simply better to have all of this things in one process. So what I … Read more