SERVER-32875 Don't stall ftdc due to running out of tickets

3 files changed, 15 insertions, 1 deletions

diff --git a/src/mongo/db/concurrency/lock_state.cpp b/src/mongo/db/concurrency/lock_state.cpp
index bf48ec3ba51..c1d02193129 100644
--- a/src/mongo/db/concurrency/lock_state.cpp
+++ b/src/mongo/db/concurrency/lock_state.cpp
@@ -311,7 +311,7 @@ LockResult LockerImpl<IsForMMAPV1>::_lockGlobalBegin(LockMode mode, Milliseconds
     dassert(isLocked() == (_modeForTicket != MODE_NONE));
     if (_modeForTicket == MODE_NONE) {
         const bool reader = isSharedLockMode(mode);
-        auto holder = ticketHolders[mode];
+        auto holder = shouldAcquireTicket() ? ticketHolders[mode] : nullptr;
         if (holder) {
             _clientState.store(reader ? kQueuedReader : kQueuedWriter);
             if (timeout == Milliseconds::max()) {
diff --git a/src/mongo/db/concurrency/locker.h b/src/mongo/db/concurrency/locker.h
index 37af569124f..10466e143b4 100644
--- a/src/mongo/db/concurrency/locker.h
+++ b/src/mongo/db/concurrency/locker.h
@@ -334,11 +334,24 @@ public:
         return _shouldConflictWithSecondaryBatchApplication;
     }
 
+    /**
+     * If set to false, this opts out of the ticket mechanism. This should be used sparingly
+     * for special purpose threads, such as FTDC.
+     */
+    void setShouldAcquireTicket(bool newValue) {
+        _shouldAcquireTicket = newValue;
+    }
+    bool shouldAcquireTicket() const {
+        return _shouldAcquireTicket;
+    }
+
+
 protected:
     Locker() {}
 
 private:
     bool _shouldConflictWithSecondaryBatchApplication = true;
+    bool _shouldAcquireTicket = true;
 };
 
 }  // namespace mongo
diff --git a/src/mongo/db/ftdc/collector.cpp b/src/mongo/db/ftdc/collector.cpp
index 611f12dff5a..7c35fb12bb6 100644
--- a/src/mongo/db/ftdc/collector.cpp
+++ b/src/mongo/db/ftdc/collector.cpp
@@ -67,6 +67,7 @@ std::tuple<BSONObj, Date_t> FTDCCollectorCollection::collect(Client* client) {
     // batches that are taking a long time.
     auto txn = client->makeOperationContext();
     txn->lockState()->setShouldConflictWithSecondaryBatchApplication(false);
+    txn->lockState()->setShouldAcquireTicket(false);
 
     for (auto& collector : _collectors) {
         BSONObjBuilder subObjBuilder(builder.subobjStart(collector->name()));