refactor(ffmpeg): 优化FFmpeg任务处理逻辑

- 添加as_completed导入以支持并发任务执行
- 实现线程池并发处理子任务，提高执行效率
- 添加任务数量监控指标
- 实现快速失败机制，及时取消剩余任务
- 增强异常处理和错误日志记录
- 添加最大工作线程数参数配置

biz/ffmpeg.py

@@ -1,7 +1,7 @@
 import json
 import os.path
 import time
-from concurrent.futures import ThreadPoolExecutor
+from concurrent.futures import ThreadPoolExecutor, as_completed
 
 from opentelemetry.trace import Status, StatusCode
 
@@ -129,13 +129,31 @@ def check_placeholder_exist_with_count(placeholder_id, task_params, required_cou
     return False
 
 
-def start_ffmpeg_task(ffmpeg_task):
+def start_ffmpeg_task(ffmpeg_task, max_workers=4):
     tracer = get_tracer(__name__)
     with tracer.start_as_current_span("start_ffmpeg_task") as span:
-        for task in ffmpeg_task.analyze_input_render_tasks():
-            result = start_ffmpeg_task(task)
-            if not result:
+        sub_tasks = list(ffmpeg_task.analyze_input_render_tasks())
+
+        if sub_tasks:
+            span.set_attribute("sub_tasks.count", len(sub_tasks))
+            with ThreadPoolExecutor(max_workers=max_workers) as executor:
+                futures = {executor.submit(start_ffmpeg_task, task, max_workers): task
+                           for task in sub_tasks}
+                for future in as_completed(futures):
+                    try:
+                        if not future.result():
+                            # 快速失败：取消剩余任务
+                            for f in futures:
+                                f.cancel()
+                            span.set_status(Status(StatusCode.ERROR))
                             return False
+                    except Exception as e:
+                        logger.error("子任务执行失败: %s", e)
+                        for f in futures:
+                            f.cancel()
+                        span.set_status(Status(StatusCode.ERROR))
+                        return False
+
         ffmpeg_task.correct_task_type()
         span.set_attribute("task.type", ffmpeg_task.task_type)
         span.set_attribute("task.center_cut", str(ffmpeg_task.center_cut))