Python Parallel Programming Cookbook

Evaluating the performance of multithread applications

In this recipe, we will verify the impact of the GIL, evaluating the performance of a multithread application. The GIL, as described in the previous chapter, is the lock introduced by the CPython interpreter. The GIL prevents parallel execution of multiple threads in the interpreter. Before being executed each thread must wait for the GIL to release the thread that is running. In fact, the interpreter forces the executing thread to acquire the GIL before it accesses anything on the interpreter itself as the stack and instances of Python objects. This is precisely the purpose of GIL—it prevents concurrent access to Python objects from different threads. The GIL then protects the memory of the ...