title: Which scheduler should I use for a "penalty box" when I do delayElement in WebFlux?
body: <p>I am trying to implement a &quot;penalty box&quot; for unsuccessful attempts to use our API when it is dealing with security tokens.  This extends my previous question <a href="https://stackoverflow.com/questions/72131993/would-delayelement-be-susceptible-to-a-dos-attack">Would delayElement be susceptible to a DoS attack?</a> which is isn't.</p>
  <p>Here's my handler at the moment.</p>
  <pre><code>.onErrorResume(
    SecurityException.class,
    ex -&gt; {
      ServerWebExchangeUtils.setResponseStatus(
        exchange, HttpStatus.UNAUTHORIZED);
      ServerWebExchangeUtils.setAlreadyRouted(exchange);
      securityLog.warn(&quot;security error obtaining claims: {}&quot;, ex.getMessage());
      return chain
        .filter(exchange)
        .delayElement(
          Duration.ofMillis(authProperties.getPenaltyDelayInMillis()), 
          penaltyScheduler
        )
        .then(
          respondWithUnauthorized(config, exchange, &quot;invalid_token&quot;));
        })
  </code></pre>
  <p>I have my scheduler as <code>Schedulers.newParallel(&quot;penalty&quot;)</code> which allows for parallel threading.  But I am not sure if parallel would be the better scheduler or should I just use boundedElastic?</p>