#### The time to answer helps the attackers { #the-time-to-answer-helps-the-attackers }

At that point, by noticing that the server took some microseconds longer to send the "Incorrect username or password" response, the attackers will know that they got _something_ right, some of the initial letters were right.

And then they can try again knowing that it's probably something more similar to `stanleyjobsox` than to `johndoe`.

Create a function to be run as the background task.

It is just a standard function that can receive parameters.

It can be an `async def` or normal `def` function, **FastAPI** will know how to handle it correctly.

In this case, the task function will write to a file (simulating sending an email).

And as the write operation doesn't use `async` and `await`, we define the function with normal `def`:

Calls are executed in one of two ways:

 * **Synchronous:** your thread blocks until the response is readable.

Also, before that, in previous versions, the `request` object was passed as part of the key-value pairs in the context for Jinja2.

///

/// tip

By declaring `response_class=HTMLResponse` the docs UI will be able to know that the response will be HTML.

///

/// note | Technical Details

You could also use `from starlette.templating import Jinja2Templates`.

				locksFailed++
				if locksFailed > tolerance {
					// We know that we are not going to get the lock anymore,
					// so exit out and release any locks that did get acquired
					done = true
				}
			}
		case <-ctx.Done():
			// Capture timedout locks as failed or took too long
			locksFailed++
			if locksFailed > tolerance {
				// We know that we are not going to get the lock anymore,

    }
    @RetainedLocalRef Object localValue = valueField;
    if (localValue != null & notInstanceOfDelegatingToFuture(localValue)) {
      return getDoneValue(localValue);
    }
    // we delay calling nanoTime until we know we will need to either park or spin
    long endNanos = remainingNanos > 0 ? System.nanoTime() + remainingNanos : 0;
    long_wait_loop:
    if (remainingNanos >= SPIN_THRESHOLD_NANOS) {
      Waiter oldHead = waitersField;

   * the more direct await* methods, but should be reliable enough in practice to avoid flakiness of
   * this test. (And if it isn't, we'd like to know about it first!)
   */
  public void testAwaitFullGc() {
    CountDownLatch finalizerRan = new CountDownLatch(1);
    WeakReference<Object> ref =
        new WeakReference<Object>(
            new Object() {

import java.math.BigInteger
import okio.Buffer
import okio.BufferedSink
import okio.ByteString

internal class DerWriter(
  sink: BufferedSink,
) {
  /** A stack of buffers that will be concatenated once we know the length of each. */
  private val stack = mutableListOf(sink)

  /** Type hints scoped to the call stack, manipulated with [pushTypeHint] and [popTypeHint]. */
  private val typeHintStack = mutableListOf<Any?>()

  /**

    public boolean remove(@Nullable Object o) {
      if (o instanceof Entry) {
        Entry<?, ?> entry = (Entry<?, ?>) o;
        if (unfiltered.containsKey(entry.getKey())
            // if this holds, then we know entry.getKey() is a K
            && keyPredicate.apply((K) entry.getKey())) {
          return unfiltered.remove(entry.getKey(), entry.getValue());
        }
      }
      return false;
    }
  }

import okhttp3.OkHttpClient;
import okhttp3.Protocol;
import okhttp3.Request;
import okhttp3.Response;

/**
 * This prints events for a single in-flight call. It won't work for multiple concurrent calls
 * because we don't know what callStartNanos refers to.
 */
public final class PrintEventsNonConcurrent {
  private final OkHttpClient client = new OkHttpClient.Builder()
      .eventListener(new PrintingEventListener())
      .build();