# Concurrency and async / await { #concurrency-and-async-await }

Details about the `async def` syntax for *path operation functions* and some background about asynchronous code, concurrency, and parallelism.

## In a hurry? { #in-a-hurry }

<abbr title="too long; didn't read"><strong>TL;DR:</strong></abbr>

If you are using third party libraries that tell you to call them with `await`, like:

```Python
results = await some_library()
```

	Mandatory         bool        `json:"mandatory"`
	Immediate         bool        `json:"immediate"`
	Durable           bool        `json:"durable"`
	Internal          bool        `json:"internal"`
	NoWait            bool        `json:"noWait"`
	AutoDeleted       bool        `json:"autoDeleted"`
	PublisherConfirms bool        `json:"publisherConfirms"`
	QueueDir          string      `json:"queueDir"`
	QueueLimit        uint64      `json:"queueLimit"`

                        // WAIT #1
                        barrier.await(1, SECONDS);

                        // WAIT #2
                        barrier.await(1, SECONDS);
                        assertTrue(executor.isShutdown());
                        assertFalse(executor.isTerminated());

                        // WAIT #3
                        barrier.await(1, SECONDS);
                        return null;

            });

            longRunningThread.start();
            startLatch.await();

            // Check active requests
            assertEquals(1, cbWithTracking.getActiveRequests(), "Should have 1 active request");

            // Complete the operation
            holdLatch.countDown();
            completeLatch.await();
            longRunningThread.join();

                        // WAIT #1
                        barrier.await(1, SECONDS);

                        // WAIT #2
                        barrier.await(1, SECONDS);
                        assertTrue(executor.isShutdown());
                        assertFalse(executor.isTerminated());

                        // WAIT #3
                        barrier.await(1, SECONDS);
                        return null;

  /** Invokes {@code latch.}{@link CountDownLatch#await() await()} uninterruptibly. */
  @J2ktIncompatible
  @GwtIncompatible // concurrency
  public static void awaitUninterruptibly(CountDownLatch latch) {
    boolean interrupted = false;
    try {
      while (true) {
        try {
          latch.await();
          return;
        } catch (InterruptedException e) {

    Thread runner = new Thread(task);
    runner.start();
    isInterruptibleRegistered.await();
    RuntimeException expected = assertThrows(RuntimeException.class, () -> task.interruptTask());
    assertThat(expected)
        .hasMessageThat()
        .isEqualTo("I bet you didn't think Thread.interrupt could throw");
    /*
     * We need to wait for the runner to exit. It used to be that the runner would get stuck in the

                        startLatch.await();
                        response.received();
                        endLatch.countDown();
                    } catch (InterruptedException e) {
                        // Ignore
                    }
                }).start();
            }

            startLatch.countDown();
            assertTrue(endLatch.await(1, TimeUnit.SECONDS));

            })
        .start();

    future.cancel(true);

    assertTrue(future.isCancelled());
    assertTrue(future.isDone());

    assertTrue(successLatch.await(200, MILLISECONDS));
    assertTrue(listenerLatch.await(200, MILLISECONDS));

    latch.countDown();

    exec.shutdown();
    exec.awaitTermination(100, MILLISECONDS);
  }

  /**

            })
        .start();

    future.cancel(true);

    assertTrue(future.isCancelled());
    assertTrue(future.isDone());

    assertTrue(successLatch.await(200, MILLISECONDS));
    assertTrue(listenerLatch.await(200, MILLISECONDS));

    latch.countDown();

    exec.shutdown();
    exec.awaitTermination(100, MILLISECONDS);
  }

  /**