SERVER-41474 Exclude writes to system.profile from Flow Control

2 files changed, 18 insertions, 0 deletions

diff --git a/src/mongo/db/commands/dbcommands_d.cpp b/src/mongo/db/commands/dbcommands_d.cpp
index 5b83d1e9877..68f07b43fd0 100644
--- a/src/mongo/db/commands/dbcommands_d.cpp
+++ b/src/mongo/db/commands/dbcommands_d.cpp
@@ -117,6 +117,11 @@ protected:
     int _applyProfilingLevel(OperationContext* opCtx,
                              const std::string& dbName,
                              int profilingLevel) const final {
+
+        // The system.profile collection is non-replicated, so writes to it do not cause
+        // replication lag. As such, they should be excluded from Flow Control.
+        opCtx->setShouldParticipateInFlowControl(false);
+
         const bool readOnly = (profilingLevel < 0 || profilingLevel > 2);
         const LockMode dbMode = readOnly ? MODE_S : MODE_X;
 
diff --git a/src/mongo/db/introspect.cpp b/src/mongo/db/introspect.cpp
index 425d100f183..3da10a1a290 100644
--- a/src/mongo/db/introspect.cpp
+++ b/src/mongo/db/introspect.cpp
@@ -121,7 +121,18 @@ void profile(OperationContext* opCtx, NetworkOp op) {
     // collection.
     bool acquireDbXLock = false;
 
+    auto origFlowControl = opCtx->shouldParticipateInFlowControl();
+
+    // The system.profile collection is non-replicated, so writes to it do not cause
+    // replication lag. As such, they should be excluded from Flow Control.
+    opCtx->setShouldParticipateInFlowControl(false);
+
+    // IX lock acquisitions beyond this block will not be related to writes to system.profile.
+    ON_BLOCK_EXIT(
+        [opCtx, origFlowControl] { opCtx->setShouldParticipateInFlowControl(origFlowControl); });
+
     try {
+
         // Even if the operation we are profiling was interrupted, we still want to output the
         // profiler entry.  This lock guard will prevent lock acquisitions from throwing exceptions
         // before we finish writing the entry. However, our maximum lock timeout overrides
@@ -167,6 +178,7 @@ void profile(OperationContext* opCtx, NetworkOp op) {
 
             Collection* const coll = db->getCollection(opCtx, db->getProfilingNS());
             if (coll) {
+                invariant(!opCtx->shouldParticipateInFlowControl());
                 WriteUnitOfWork wuow(opCtx);
                 OpDebug* const nullOpDebug = nullptr;
                 coll->insertDocument(opCtx, InsertStatement(p), nullOpDebug, false)
@@ -202,6 +214,7 @@ void profile(OperationContext* opCtx, NetworkOp op) {
 
 Status createProfileCollection(OperationContext* opCtx, Database* db) {
     invariant(opCtx->lockState()->isDbLockedForMode(db->name(), MODE_X));
+    invariant(!opCtx->shouldParticipateInFlowControl());
 
     auto& dbProfilingNS = db->getProfilingNS();
     Collection* const collection = db->getCollection(opCtx, dbProfilingNS);