Modify threadpool task queue

Author: dt3310321

qcloud_cos/cos_threadpool.py

@@ -43,9 +43,9 @@ def get_result(self):
 
 class SimpleThreadPool:
 
-    def __init__(self, num_threads=5):
+    def __init__(self, num_threads=5, num_queue=0):
         self._num_threads = num_threads
-        self._queue = Queue()
+        self._queue = Queue(num_queue)
         self._lock = Lock()
         self._active = False
         self._workers = list()