SERVER-37313 Secondary foreground index build should take Database X rather than Global X lockr3.6.9-rc0r3.6.9

1 files changed, 6 insertions, 0 deletions

diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index 773f3c4da84..4e0474f9031 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -243,6 +243,12 @@ void createIndexForApplyOps(OperationContext* opCtx,
                             const BSONObj& indexSpec,
                             const NamespaceString& indexNss,
                             IncrementOpsAppliedStatsFn incrementOpsAppliedStats) {
+    // Since 'createIndexes' is a 'c' oplog entry, it takes the Global X lock. However, we don't
+    // want index build to block FTDC thread which periodically gathers data with Global IS lock.
+    // Put this hack to release the Global X lock and take the Global IX instead.
+    Lock::TempRelease tempRelease(opCtx->lockState());
+    Lock::DBLock lock(opCtx, indexNss.db(), MODE_X);
+
     // Check if collection exists.
     Database* db = dbHolder().get(opCtx, indexNss.ns());
     auto indexCollection = db ? db->getCollection(opCtx, indexNss) : nullptr;