override fun onFailure(
          hostname: String,
          e: IOException,
        ) {
          exception = e
          latch.countDown()
        }
      },
    )

    latch.await()

    return Pair(allAddresses, exception)
  }

  @Test
  fun testDnsRequestExternal() {
    assumeNetwork()

    val (allAddresses, exception) = dnsQuery("google.com")

    // (which will block) in the same thread.
    new Thread() {
      @Override
      public void run() {
        inputFuture.set(SLOW_FUNC_VALID_INPUT_DATA);
      }
    }.start();
    funcIsWaitingLatch.await();

    assertTrue(resultFuture.cancel(true));
    assertTrue(resultFuture.isCancelled());
    assertFalse(inputFuture.isCancelled());
    assertFalse(outputFuture.isCancelled());

    // (which will block) in the same thread.
    new Thread() {
      @Override
      public void run() {
        inputFuture.set(SLOW_FUNC_VALID_INPUT_DATA);
      }
    }.start();
    funcIsWaitingLatch.await();

    assertTrue(resultFuture.cancel(true));
    assertTrue(resultFuture.isCancelled());
    assertFalse(inputFuture.isCancelled());
    assertFalse(outputFuture.isCancelled());

Dans cet exemple, la fonction de tâche écrira dans un fichier (afin de simuler un envoi d'email).

L'opération d'écriture n'utilisant ni `async` ni `await`, on définit la fonction avec un `def` normal.

{* ../../docs_src/background_tasks/tutorial001.py hl[6:9] *}

## Ajouter une tâche d'arrière-plan

      lock.lock();
      try {
        locked.countDown();
        finishLatch.await(1, MINUTES);
      } catch (InterruptedException e) {
        fail(e.toString());
      } finally {
        lock.unlock();
      }
    }

    void waitUntilHoldingLock() throws InterruptedException {
      locked.await(1, MINUTES);
    }

    void releaseLockAndFinish() throws InterruptedException {

      lock.lock();
      try {
        locked.countDown();
        finishLatch.await(1, MINUTES);
      } catch (InterruptedException e) {
        fail(e.toString());
      } finally {
        lock.unlock();
      }
    }

    void waitUntilHoldingLock() throws InterruptedException {
      locked.await(1, MINUTES);
    }

    void releaseLockAndFinish() throws InterruptedException {

        doneSignal.countDown();
      }
    }.start();

    try {
      computingSignal.await();
    } catch (InterruptedException e) {
      throw new RuntimeException(e);
    }

    map.put(one, two);
    assertSame(two, map.get(one));
    startSignal.countDown();

    try {
      doneSignal.await();
    } catch (InterruptedException e) {
      throw new RuntimeException(e);
    }

        doneSignal.countDown();
      }
    }.start();

    try {
      computingSignal.await();
    } catch (InterruptedException e) {
      throw new RuntimeException(e);
    }

    map.put(one, two);
    assertSame(two, map.get(one));
    startSignal.countDown();

    try {
      doneSignal.await();
    } catch (InterruptedException e) {
      throw new RuntimeException(e);
    }

    public @Nullable Void call() throws InterruptedException {
      running = true;
      startLatch.countDown();
      stopLatch.await();
      running = false;
      return null;
    }

    public void waitForStart() throws InterruptedException {
      startLatch.await();
    }

    public void stop() {
      stopLatch.countDown();
    }

    public boolean isRunning() {

          fail("")
        }
      },
    )
    assertThat(server.takeRequest().sequenceNumber)
      .isEqualTo(expectedSequenceNumber)
    responseDequeuedLatch!!.await()
    call.cancel()
    requestCanceledLatch!!.countDown()
    latch.await()
  }

  @ParameterizedTest
  @ArgumentsSource(ProtocolParamProvider::class)
  fun noRecoveryFromRefusedStreamWithRetryDisabled(
    protocol: Protocol,