Are locks unnecessary in multithreaded Python code because of the GIL

Published: 22 September 2023
on channel: CodeGPT
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thread-local storage (tls) is a concept in multithreading and parallel programming that allows you to store data in a way that each thread in a multithreaded python program has its own separate copy of the data. this means that each thread can access and modify its own unique copy of the data without affecting other threads. thread-local storage is particularly useful when you have shared data that needs to be accessed and modified by multiple threads concurrently, but you want to maintain thread-specific state or data.
in python, you can use the threading.local() class from the threading module to implement thread-local storage. this class provides a simple and convenient way to create thread-local variables.
isolation: when multiple threads are running concurrently, they can potentially interfere with each other when accessing shared data. thread-local storage allows you to isolate data for each thread, reducing the risk of race conditions and synchronization issues.
performance: in some cases, thread-local data can improve performance by avoiding the need for locks or synchronization mechanisms. since each thread has its own copy of the data, there is no contention between threads when accessing or modifying it.
maintaining state: thread-local storage is useful for maintaining thread-specific state or configuration settings. for example, in a web application, you might want to store user-specific data in thread-local variables to avoid passing it explicitly through function calls.
now, let's dive into a code example to see how thread-local storage works in python:
in this example:
we create a thread-local storage object using threading.local().
the set_thread_data() function sets thread-local data, and get_thread_data() retrieves it.
we create five threads, each running the worker() function. inside worker(), we set thread-local data and then retrieve and print it. each thread operates on its own copy of thread_local_data.data.
finally, we start the threads and w ...