SERVER-23003: Wait for synctail to clear the buffer.

(cherry picked from commit 7a8fae34f9949fadc515c47d956bbbc464842664)

1 files changed, 10 insertions, 0 deletions

diff --git a/src/mongo/db/repl/bgsync.cpp b/src/mongo/db/repl/bgsync.cpp
index 23b6fd97d39..6c69a0a3269 100644
--- a/src/mongo/db/repl/bgsync.cpp
+++ b/src/mongo/db/repl/bgsync.cpp
@@ -696,7 +696,17 @@ void BackgroundSync::_rollback(OperationContext* txn,
                                RollbackSourceImpl(getConnection, source, rsOplogName),
                                _replCoord);
     if (status.isOK()) {
+        // When the syncTail thread sees there is no new data by adding something to the buffer.
         _signalNoNewDataForApplier();
+        // Wait until the buffer is emtpy.
+        // This is an indication that syncTail has removed the sentinal marker from the buffer
+        // and reset its local lastAppliedOpTime via the replCoord.
+        while (!_buffer.empty()) {
+            sleepmillis(10);
+            if (inShutdown()) {
+                return;
+            }
+        }
         return;
     }
     if (ErrorCodes::UnrecoverableRollbackError == status.code()) {