In what situations is the execution thread transferred to the GIL in Python?

GIL (Global Interpreter Lock) in Python is a mechanism that allows only one thread to execute Python bytecode at any given time.

The execution thread is passed the GIL in the following situations:

• When the current thread has executed a certain number of bytecodes (by default about 5 milliseconds), the interpreter attempts to pass the GIL to another thread.
• When a thread explicitly releases the GIL, for example, during blocking I/O operations or when calling C extensions that release the GIL.

Thus, thread switching occurs either on a timer or during blocking operations, allowing other threads the opportunity to run.

Example: if a thread is performing a long computational task in Python, the GIL will not be passed until the time quantum expires or a call that releases the GIL occurs.