Using multiple threads

Godot supports threads and provides many handy functions to use them.

Note

If using other languages (C#, C++), it may be easier to use the threading classes they support.

Creating a thread is very simple, just use the following code:

Your function will, then, run in a separate thread until it returns. Even if the function has returned already, the thread must collect it, so call , which will wait until the thread is done (if not done yet), then properly dispose of it.

Accessing objects or data from multiple threads is not always supported (if you do it, it will cause unexpected behaviors or crashes). Read the Thread-safe APIs documentation to understand which engine APIs support multiple thread access.

When processing your own data or calling your own functions, as a rule, try to avoid accessing the same data directly from different threads. You may run into synchronization problems, as the data is not always updated between CPU cores when modified. Always use a when accessing a piece of data from different threads.

When calling Mutex.lock(), a thread ensures that all other threads will be blocked (put on suspended state) if they try to lock the same mutex. When the mutex is unlocked by calling , the other threads will be allowed to proceed with the lock (but only one at a time).

GDScript

Sometimes you want your thread to work “on demand”. In other words, tell it when to work and let it suspend when it isn’t doing anything. For this, Semaphores are used. The function is used in the thread to suspend it until some data arrives.

The main thread, instead, uses Semaphore.post() to signal that data is ready to be processed:

GDScript