# Heapq vs. Q.PriorityQueue

{% embed url="https://stackoverflow.com/questions/36991716/whats-the-difference-between-heapq-and-priorityqueue-in-python" %}

`Queue.PriorityQueue` is a thread-safe class, while the `heapq`module makes no thread-safety guarantees. From the [`Queue`module documentation](https://docs.python.org/2/library/queue.html):

> The `Queue` module implements multi-producer, multi-consumer queues. It is especially useful in threaded programming when information must be exchanged safely between multiple threads. The `Queue` class in this module implements all the required locking semantics. It depends on the availability of thread support in Python; see the `threading` module.

The `heapq` module offers no locking, and operates on standard `list` objects, which are not meant to be thread-safe.

In fact, the `PriorityQueue` _implementation_ uses `heapq` under the hood to do all prioritisation work, with the base `Queue` class providing the locking to make this thread-safe. See the [source code](https://hg.python.org/cpython/file/v2.7.11/Lib/Queue.py#l212)for details.

This makes the `heapq` module faster; there is no locking overhead. In addition, you are free to use the various `heapq` functions in different, novel ways, the `PriorityQueue` only offers the straight-up queueing functionality.
