title: Parallel save error in mongoose post init hook. Can't save() the same doc multiple times in parallel
body: <p>So here's a problem which i am facing when i am using the post init hook whenever the date changes i update some values in the db. but when i am trying to make a get call the parallel save error comes up, but the values in database get updated and if i try to hit api again it works perfectly fine, so why do i get this parallel save error just once and not again until the date changes again.</p>
  
  <pre><code>influencerSchema.post('init', async function (doc) {
    let metaData = influencerModel.metaData();
    let refreshFields = metaData.refreshFields;
    for (let i = 0; i &lt; refreshFields.length; i++) {
      if (new Date(doc.currentMembership[refreshFields[i]].dailyCount.date).setHours(0, 0, 0, 0) != new Date().setHours(0, 0, 0, 0)) {
        doc.currentMembership[refreshFields[i]].dailyCount.date = Date.now();
        doc.currentMembership[refreshFields[i]].dailyCount.count = doc.currentMembership[refreshFields[i]].count;
        await doc.save();
      }
    }
  });
  </code></pre>
  
  <p>here refresh fields are </p>
  
  <pre><code>refreshFields: ['likes', 'messages', 'matches', 'backtrack']
  </code></pre>
  
  <p>any help would be great
  Thanks!</p>