Class WorkerThreadPool
- Namespace
- Godot
- Assembly
- GodotSharp.dll
The WorkerThreadPool singleton allocates a set of GodotThreads (called worker threads) on project startup and provides methods for offloading tasks to them. This can be used for simple multithreading without having to create GodotThreads.
Tasks hold the Callable to be run by the threads. WorkerThreadPool can be used to create regular tasks, which will be taken by one worker thread, or group tasks, which can be distributed between multiple worker threads. Group tasks execute the Callable multiple times, which makes them useful for iterating over a lot of elements, such as the enemies in an arena.
Here's a sample on how to offload an expensive function to worker threads:
private List<Node> _enemies = new List<Node>(); // A list to be filled with enemies.
private void ProcessEnemyAI(int enemyIndex)
{
Node processedEnemy = _enemies[enemyIndex];
// Expensive logic here.
}
public override void _Process(double delta)
{
long taskId = WorkerThreadPool.AddGroupTask(Callable.From<int>(ProcessEnemyAI), _enemies.Count);
// Other code...
WorkerThreadPool.WaitForGroupTaskCompletion(taskId);
// Other code that depends on the enemy AI already being processed.
}
The above code relies on the number of elements in the enemies array remaining constant during the multithreaded part.
Note: Using this singleton could affect performance negatively if the task being distributed between threads is not computationally expensive.
public static class WorkerThreadPool- Inheritance
-
WorkerThreadPool
- Inherited Members
Properties
Singleton
public static WorkerThreadPoolInstance Singleton { get; }Property Value
Methods
AddGroupTask(Callable, int, int, bool, string)
Adds action as a group task to be executed by the worker threads. The Callable will be called a number of times based on elements, with the first thread calling it with the value 0 as a parameter, and each consecutive execution incrementing this value by 1 until it reaches element - 1.
The number of threads the task is distributed to is defined by tasksNeeded, where the default value -1 means it is distributed to all worker threads. highPriority determines if the task has a high priority or a low priority (default). You can optionally provide a description to help with debugging.
Returns a group task ID that can be used by other methods.
public static long AddGroupTask(Callable action, int elements, int tasksNeeded = -1, bool highPriority = false, string description = "")Parameters
Returns
AddTask(Callable, bool, string)
Adds action as a task to be executed by a worker thread. highPriority determines if the task has a high priority or a low priority (default). You can optionally provide a description to help with debugging.
Returns a task ID that can be used by other methods.
public static long AddTask(Callable action, bool highPriority = false, string description = "")Parameters
Returns
GetGroupProcessedElementCount(long)
Returns how many times the Callable of the group task with the given ID has already been executed by the worker threads.
Note: If a thread has started executing the Callable but is yet to finish, it won't be counted.
public static uint GetGroupProcessedElementCount(long groupId)Parameters
groupIdlong
Returns
IsGroupTaskCompleted(long)
Returns true if the group task with the given ID is completed.
public static bool IsGroupTaskCompleted(long groupId)Parameters
groupIdlong
Returns
IsTaskCompleted(long)
Returns true if the task with the given ID is completed.
public static bool IsTaskCompleted(long taskId)Parameters
taskIdlong
Returns
WaitForGroupTaskCompletion(long)
Pauses the thread that calls this method until the group task with the given ID is completed.
public static void WaitForGroupTaskCompletion(long groupId)Parameters
groupIdlong
WaitForTaskCompletion(long)
Pauses the thread that calls this method until the task with the given ID is completed.
Returns Ok if the task could be successfully awaited.
Returns InvalidParameter if a task with the passed ID does not exist (maybe because it was already awaited and disposed of).
Returns Busy if the call is made from another running task and, due to task scheduling, the task to await is at a lower level in the call stack and therefore can't progress. This is an advanced situation that should only matter when some tasks depend on others.
public static Error WaitForTaskCompletion(long taskId)Parameters
taskIdlong