queue — 同步队列类 ¶

Queue 对象 ¶

Queue 对象 ( Queue , LifoQueue ，或 PriorityQueue ) 提供的公共方法的描述见下文。

Queue. qsize ( ) ¶

Return the approximate size of the queue. Note, qsize() > 0 doesn’t guarantee that a subsequent get() will not block, nor will qsize() < maxsize guarantee that put() will not block.

Queue. empty ( ) ¶

返回 True 若队列为空， False 否则。若 empty() 返回 True it doesn’t guarantee that a subsequent call to put() will not block. Similarly, if empty() returns False it doesn’t guarantee that a subsequent call to get() will not block.

Queue. full ( ) ¶

返回 True 若队列是满的， False 否则。若 full() 返回 True it doesn’t guarantee that a subsequent call to get() will not block. Similarly, if full() returns False it doesn’t guarantee that a subsequent call to put() will not block.

Queue. put ( item , block=True , timeout=None ) ¶

Put item 进队列。若可选自变量 block 为 True 和 timeout is None (默认)，阻塞若有必要直到空闲槽可用。若 timeout 是正数，它阻塞最多 timeout 秒并引发 Full 异常若在该时间内无可用空闲槽。否则 ( block 为 False)，将项放入队列若空闲槽立即可用，否则引发 Full 异常 ( timeout 被忽略在这种情况下)。

Queue. put_nowait ( item ) ¶

相当于 put(item, False) .

Queue. get ( block=True , timeout=None ) ¶

移除并返回项从队列。若可选自变量 block 为 True 和 timeout is None (默认)，阻塞若有必要直到项可用。若 timeout 是正数，它阻塞最多 timeout 秒并引发 Empty 异常若在该时间内无可用项。否则 ( block 为 False)，返回项若立即可用，否则引发 Empty 异常 ( timeout 被忽略在这种情况下)。

Prior to 3.0 on POSIX systems, and for all versions on Windows, if block 为 True 和 timeout is None , this operation goes into an uninterruptible wait on an underlying lock. This means that no exceptions can occur, and in particular a SIGINT will not trigger a KeyboardInterrupt .

Queue. get_nowait ( ) ¶

相当于 get(False) .

Two methods are offered to support tracking whether enqueued tasks have been fully processed by daemon consumer threads.

Queue. task_done ( ) ¶

Indicate that a formerly enqueued task is complete. Used by queue consumer threads. For each get() used to fetch a task, a subsequent call to task_done() tells the queue that the processing on the task is complete.

若 join() is currently blocking, it will resume when all items have been processed (meaning that a task_done() call was received for every item that had been put() into the queue).

引发 ValueError if called more times than there were items placed in the queue.

Queue. join ( ) ¶

Blocks until all items in the queue have been gotten and processed.

The count of unfinished tasks goes up whenever an item is added to the queue. The count goes down whenever a consumer thread calls task_done() to indicate that the item was retrieved and all work on it is complete. When the count of unfinished tasks drops to zero, join() unblocks.

Example of how to wait for enqueued tasks to be completed:

import threading, queue
q = queue.Queue()
def worker():
    while True:
        item = q.get()
        print(f'Working on {item}')
        print(f'Finished {item}')
        q.task_done()
# turn-on the worker thread
threading.Thread(target=worker, daemon=True).start()
# send thirty task requests to the worker
for item in range(30):
    q.put(item)
print('All task requests sent\n', end='')
# block until all tasks are done
q.join()
print('All work completed')
								

SimpleQueue 对象 ¶

SimpleQueue 对象提供的公共方法的描述见下文。

SimpleQueue. qsize ( ) ¶

Return the approximate size of the queue. Note, qsize() > 0 doesn’t guarantee that a subsequent get() will not block.

SimpleQueue. empty ( ) ¶

返回 True 若队列为空， False 否则。若 empty() 返回 False it doesn’t guarantee that a subsequent call to get() will not block.

SimpleQueue. put ( item , block=True , timeout=None ) ¶

Put item into the queue. The method never blocks and always succeeds (except for potential low-level errors such as failure to allocate memory). The optional args block and timeout are ignored and only provided for compatibility with Queue.put() .

CPython 实现细节： This method has a C implementation which is reentrant. That is, a put() or get() call can be interrupted by another put() call in the same thread without deadlocking or corrupting internal state inside the queue. This makes it appropriate for use in destructors such as __del__ methods or weakref 回调。

SimpleQueue. put_nowait ( item ) ¶

相当于 put(item) ，提供是为兼容 Queue.put_nowait() .

SimpleQueue. get ( block=True , timeout=None ) ¶

移除并返回项从队列。若可选自变量 block 为 True 和 timeout is None (默认)，阻塞若有必要直到项可用。若 timeout 是正数，它阻塞最多 timeout 秒并引发 Empty 异常若在该时间内无可用项。否则 ( block 为 False)，返回项若立即可用，否则引发 Empty 异常 ( timeout 被忽略在这种情况下)。

SimpleQueue. get_nowait ( ) ¶

相当于 get(False) .