Thread¶
A unit of execution in a process.
Description¶
A unit of execution in a process. Can run methods on Objects simultaneously. The use of synchronization via Mutex or Semaphore is advised if working with shared objects.
Note: Breakpoints won't break on code if it's running in a thread. This is a current limitation of the GDScript debugger.
Warning:
To guarantee that the operating system is able to perform proper cleanup (no crashes, no deadlocks), these conditions must be met by the time a Thread's reference count reaches zero and therefore it is destroyed:
It must not have any Mutex objects locked.
It must not be waiting on any Semaphore objects.
wait_to_finish should have been called on it.
Tutorials¶
Methods¶
get_id ( ) const |
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is_active ( ) const |
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is_alive ( ) const |
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start ( Object instance, String method, Variant userdata=null, Priority priority=1 ) |
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wait_to_finish ( ) |
Enumerations¶
enum Priority:
Priority PRIORITY_LOW = 0
A thread running with lower priority than normally.
Priority PRIORITY_NORMAL = 1
A thread with a standard priority.
Priority PRIORITY_HIGH = 2
A thread running with higher priority than normally.
Method Descriptions¶
String get_id ( ) const
Returns the current Thread's ID, uniquely identifying it among all threads. If the Thread is not running this returns an empty string.
bool is_active ( ) const
Returns true if this Thread has been started. Once started, this will return true until it is joined using wait_to_finish. For checking if a Thread is still executing its task, use is_alive.
bool is_alive ( ) const
Returns true if this Thread is currently running. This is useful for determining if wait_to_finish can be called without blocking the calling thread.
To check if a Thread is joinable, use is_active.
Error start ( Object instance, String method, Variant userdata=null, Priority priority=1 )
Starts a new Thread that runs method on object instance with userdata passed as an argument. Even if no userdata is passed, method must accept one argument and it will be null. The priority of the Thread can be changed by passing a value from the Priority enum.
Returns @GlobalScope.OK on success, or @GlobalScope.ERR_CANT_CREATE on failure.
Variant wait_to_finish ( )
Joins the Thread and waits for it to finish. Returns the output of the method passed to start.
Should either be used when you want to retrieve the value returned from the method called by the Thread or before freeing the instance that contains the Thread.
To determine if this can be called without blocking the calling thread, check if is_alive is false.
Note: After the Thread finishes joining it will be disposed. If you want to use it again you will have to create a new instance of it.