Global interpreter lock

Mechanism that ensures threads are not executed in parallel

A global interpreter lock (GIL) is a mechanism used in computer-language interpreters to synchronize the execution of threads so that only one native thread can execute basic operations at a time. As a general rule, an interpreter that uses GIL will see only one thread to execute at a time, even if runs on a multi-core processor, although some implementations provide for CPU intensive code to release the GIL, allowing multiple threads to use multiple cores. Some popular interpreters that have GIL are CPython and Ruby MRI.

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