GIL or Global Interpreter Lock is a mechanism used in the CPython implementation of Python programming language to synchronize the execution of threads and prevent multiple native threads from executing Python bytecodes at once. This lock is necessary because CPython’s memory management is not thread-safe.
The GIL reduces the performance of multithreaded Python programs because only one thread at a time can execute Python bytecode. Even on a multiprocessor or multicore system, a Python program using multithreading will usually not run more than one thread’s bytecode at a time. Hence, it is often not the ideal tool for CPU-bound tasks that require concurrent processing, and instead, multiprocessing is the preferable method. However, it does not impact I/O-bound tasks as much since these usually involve a lot of waiting for resources where other threads can be scheduled.
