title: using pino multistream with synchronous logging
body: <p>from what I understand, Pino (v 7.5.1) by default does sync logging. From the docs</p>
  <blockquote>
  <p>In Pino's standard mode of operation log messages are directly written to the output stream as the messages are generated with a blocking operation.</p>
  </blockquote>
  <p>I am using <code>pino.multistreams</code> like so</p>
  <pre class="lang-js prettyprint-override"><code>const pino = require('pino')
  const pretty = require('pino-pretty')
  const logdir = '/Users/punkish/Projects/z/logs'
  
  const streams = [
      {stream: fs.createWriteStream(`${logdir}/info.log`, {flags: 'a'})},
      {stream: pretty()},
      {level: 'error', stream: fs.createWriteStream(`${logdir}/error.log`, {flags: 'a'})},
      {level: 'debug', stream: fs.createWriteStream(`${logdir}/debug.log`, {flags: 'a'})},
      {level: 'fatal', stream: fs.createWriteStream(`${logdir}/fatal.log`, {flags: 'a'})}
  ]
  </code></pre>
  <p>Strangely, Pino is behaving asynchronously. I have a <code>curl</code> operation that is outputting out of sequence (before earlier events that are using <code>log.info</code>)</p>
  <pre class="lang-js prettyprint-override"><code>log.info('1')
  .. code to do 1 something
  
  log.info('2')
  .. code to do 2 something
  
  log.info('3')
  .. code to do 3 something
  
  const execSync = require('child_process').execSync
  execSync(curl --silent --output ${local} '${remote}')
  </code></pre>
  <p>and my <code>console</code> output is</p>
  <pre class="lang-sh prettyprint-override"><code>1
    % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                   Dload  Upload   Total   Spent    Left  Speed
  100 39.5M  100 39.5M    0     0   108M      0 --:--:-- --:--:-- --:--:--  113M
  2
  3
  </code></pre>
  <p>this is a bit annoying and confusing. Maybe this is not the fault of Pino, and maybe <code>curl</code> is causing the problem. But if I replace pino logging with <code>console.log</code> then the order is as expected. So it seems the problem is with Pino behaving asynchronously. How can I go back to synchronous logging?</p>