from panda3d.core import Semaphore
class Semaphore

A classic semaphore synchronization primitive.

A semaphore manages an internal counter which is decremented by each acquire() call and incremented by each release() call. The counter can never go below zero; when acquire() finds that it is zero, it blocks, waiting until some other thread calls release().

Inheritance diagram

Inheritance diagram of Semaphore

__init__(initial_count: int)

Decrements the internal count. If the count was already at zero, blocks until the count is nonzero, then decrements it.


Returns the current semaphore count. Note that this call is not thread- safe (the count may change at any time).

output(out: ostream)

Increments the semaphore’s internal count. This may wake up another thread blocked on acquire().

Returns the count of the semaphore upon release.


If the semaphore can be acquired without blocking, does so and returns true. Otherwise, returns false.