Locks for capped collection's metadata in CollectionImpl don't seem to do what they claim

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    • Type: Bug
    • Resolution: Community Answered
    • Priority: Major - P3
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    • Affects Version/s: None
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      There are two identical pieces of code in CollectionImpl::_insertDocuments() and CollectionImpl::updateDocument() that grab metadata X-lock for capped collections:

       

      if (_shared->_needCappedLock) {
 // X-lock the metadata resource for this capped collection until the end of the WUOW. This
 // prevents the primary from executing with more concurrency than secondaries.
 // See SERVER-21646.
 Lock::ResourceLock heldUntilEndOfWUOW{
 opCtx->lockState(), ResourceId(RESOURCE_METADATA, _ns.ns()), MODE_X};
}

      The lock won't be held until the end of WUOW as it will be released after leaving the scope.

      Is the comment wrong or is the code wrong?

            Assignee:
            Dmitry Agranat
            Reporter:
            Denis Protivensky
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              Created:
              Updated:
              Resolved: