NSThread or pythons' threading module in pyobjc?

Question

I need to do some network bound calls (e.g., fetch a website) and I don't want it to block the UI. Should I be using NSThread's or python's threading module if I am working in pyobjc? I can't find any information on how to choose one over the other. Note, I don't really care about Python's GIL since my tasks are not CPU bound at all.

Answer 1

It will make no difference, you will gain the same behavior with slightly different interfaces. Use whichever fits best into your system.

Answer 2

Learn to love the run loop. Use Cocoa's URL-loading system (or, if you need plain sockets, NSFileHandle) and let it call you when the response (or failure) comes back. Then you don't have to deal with threads at all (the URL-loading system will use a thread for you).

Pretty much the only time to create your own threads in Cocoa is when you have a large task (>0.1 sec) that you can't break up.

(Someone might say NSOperation, but NSOperationQueue is broken and RAOperationQueue doesn't support concurrent operations. Fine if you already have a bunch of NSOperationQueue code or really want to prepare for working NSOperationQueue, but if you need concurrency now, run loop or threads.)

Answer 3

I'm more fond of the native python threading solution since I could join and reference threads around. AFAIK, NSThreads don't support thread joining and cancelling, and you could get a variety of things done with python threads.

Also, it's a bummer that NSThreads can't have multiple arguments, and though there are workarounds for this (like using NSDictionarys and NSArrays), it's still not as elegant and as simple as invoking a thread with arguments laid out in order / corresponding parameters.

But yeah, if the situation demands you to use NSThreads, there shouldn't be any problem at all. Otherwise, it's cool to stick with native python threads.

Answer 4

I have a different suggestion, mainly because python threading is just plain awful because of the GIL (Global Interpreter Lock), especially when you have more than one cpu core. There is a video presentation that goes into this in excruciating detail, but I cannot find the video right now - it was done by a Google employee.

Anyway, you may want to think about using the subprocess module instead of threading (have a helper program that you can execute, or use another binary on the system. Or use NSThread, it should give you more performance than what you can get with CPython threads.