From 8192d1cbc7cb2c079ae07da692e0b7447c319b37 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pedro=20J=2E=20Est=C3=A9banez?= <pedrojrulez@gmail.com>
Date: Thu, 18 Apr 2024 19:05:44 +0200
Subject: [PATCH] WorkerThreadPool: Fix yield-over for not-yet-started tasks

---
 core/object/worker_thread_pool.cpp | 9 ++++++++-
 core/object/worker_thread_pool.h   | 5 ++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/core/object/worker_thread_pool.cpp b/core/object/worker_thread_pool.cpp
index e0b8730a672d..9c9e0fa89917 100644
--- a/core/object/worker_thread_pool.cpp
+++ b/core/object/worker_thread_pool.cpp
@@ -72,6 +72,9 @@ void WorkerThreadPool::_process_task(Task *p_task) {
 		p_task->pool_thread_index = pool_thread_index;
 		prev_task = curr_thread.current_task;
 		curr_thread.current_task = p_task;
+		if (p_task->pending_notify_yield_over) {
+			curr_thread.yield_is_over = true;
+		}
 		task_mutex.unlock();
 	}
 #endif
@@ -491,7 +494,11 @@ void WorkerThreadPool::notify_yield_over(TaskID p_task_id) {
 		ERR_FAIL_MSG("Invalid Task ID.");
 	}
 	Task *task = *taskp;
-	if (task->completed) {
+	if (task->pool_thread_index == -1) { // Completed or not started yet.
+		if (!task->completed) {
+			// This avoids a race condition where a task is created and yield-over called before it's processed.
+			task->pending_notify_yield_over = true;
+		}
 		task_mutex.unlock();
 		return;
 	}
diff --git a/core/object/worker_thread_pool.h b/core/object/worker_thread_pool.h
index 64f24df79fde..a9cf260a0f29 100644
--- a/core/object/worker_thread_pool.h
+++ b/core/object/worker_thread_pool.h
@@ -81,7 +81,8 @@ private:
 		void *native_func_userdata = nullptr;
 		String description;
 		Semaphore done_semaphore; // For user threads awaiting.
-		bool completed = false;
+		bool completed : 1;
+		bool pending_notify_yield_over : 1;
 		Group *group = nullptr;
 		SelfList<Task> task_elem;
 		uint32_t waiting_pool = 0;
@@ -92,6 +93,8 @@ private:
 
 		void free_template_userdata();
 		Task() :
+				completed(false),
+				pending_notify_yield_over(false),
 				task_elem(this) {}
 	};