必要时使用线程和锁？

Question

Say I have an empty multidimensional list data = [[], []] and a function which appends values to one of the sublists:

def append(data):
   #appending values to data

I start two threads, each appending data to one of the respective sublists:

t1 = threading.Thread(target = append, args = [data[0]])
t2 = threading.Thread(target = append, args = [data[1]])

Do I have to worry that this is going to mess things up? I'm new to threading and I read that you have to use locks because there can be a problem when threads try to access a variable at the same time. But I haven't see any problem with my code. Is it okay in this case because the threads access different sub-arrays?

Answer 1

As you're using different lists, you won't have an issue at all.

In fact, if all you're doing is appending, and don't mind the order, you may even use the same list and append to it from different threads.

The default Python implementation, CPython, has a GIL (Global Interpreter Lock). Apart from memory management, the GIL makes sure single operations on pure mutable builtin primitives, such as dict, list and set, will cause no interference.