Threading Flashcards
Thread
A flow of execution. Like a separate order of instructions. However each thread takes a turn running to achieve concurrency.
GIL
Global interpreter lock- allows only one thread to hold the control of the Python interpreter at any one time
Cpu bound
Program/task spends most of its time waiting for internal events (CPU intensive) uses multiprocessing
Io bound
Program/task spends most of its time waiting for external events(user input, web scraping)
Uses multithreading
Daemon thread
A thread that runs in the background, not important for program to run, your program won’t wait got daemon threads to complete before exiting, non- daemon threads cannot normally be killed, stay alive till complete
E.g background tasks, waiting for input , garbage collection, long processes
Syntax for normal thread
Variable = threading.thread(target=-function-)
Daemon thread syntax
Variable = threading.thread(target=-function-, daemon=True)
To check if a thread is a daemon thread
Print(x.isdaemon)
Multiprocessing explained:
Running tasks in parallel on different cpu cores, bypassed GIL used for threading
What are multithreading and multiprocessing good for?
Multiprocessing = better for cpu bound tasks (heavy cpu usage)
Multithreading = better for io bound tasks (waiting around)
What does “ if __name__ == ‘__main__’:
main()
Def main():
Pass
It means that when child processes are made from the main module they will copy them but won’t execute
What are the parameters for a thread?
Variable = threading.thread(target=~~,args=(~~))
Process syntax
Variable = process(target=~~,args=(~~))
Variable.start
What function gives synchronicity?
Join() function
What part of the cpu completes processes?
The cpu cores
What is the amount of processes you can complete at one time dependent on?
How many cores you have
