SERVER-30831 Log dropped writes at a limited rate when dbCheck health log buffer is full

1 files changed, 18 insertions, 1 deletions

diff --git a/src/mongo/db/concurrency/deferred_writer.cpp b/src/mongo/db/concurrency/deferred_writer.cpp
index 0ffa4a7c353..fe2551bb568 100644
--- a/src/mongo/db/concurrency/deferred_writer.cpp
+++ b/src/mongo/db/concurrency/deferred_writer.cpp
@@ -41,7 +41,7 @@
 namespace mongo {
 
 namespace {
-auto kLogInterval = stdx::chrono::hours(1);
+auto kLogInterval = stdx::chrono::minutes(1);
 }
 
 void DeferredWriter::_logFailure(const Status& status) {
@@ -51,6 +51,16 @@ void DeferredWriter::_logFailure(const Status& status) {
     }
 }
 
+void DeferredWriter::_logDroppedEntry() {
+    _droppedEntries += 1;
+    if (TimePoint::clock::now() - _lastLoggedDrop > kLogInterval) {
+        log() << "Deferred write buffer for " << _nss.toString() << " is full. " << _droppedEntries
+              << " entries have been dropped.";
+        _lastLoggedDrop = stdx::chrono::system_clock::now();
+        _droppedEntries = 0;
+    }
+}
+
 Status DeferredWriter::_makeCollection(OperationContext* opCtx) {
     BSONObjBuilder builder;
     builder.append("create", _nss.coll());
@@ -122,6 +132,7 @@ DeferredWriter::DeferredWriter(NamespaceString nss, CollectionOptions opts, int6
       _maxNumBytes(maxSize),
       _nss(nss),
       _numBytes(0),
+      _droppedEntries(0),
       _lastLogged(TimePoint::clock::now() - kLogInterval) {}
 
 DeferredWriter::~DeferredWriter() {}
@@ -160,6 +171,7 @@ bool DeferredWriter::insertDocument(BSONObj obj) {
     if (_numBytes + obj.objsize() >= _maxNumBytes) {
         // If not, drop it.  We always drop new entries rather than old ones; that way the caller
         // knows at the time of the call that the entry was dropped.
+        _logDroppedEntry();
         return false;
     }
 
@@ -170,4 +182,9 @@ bool DeferredWriter::insertDocument(BSONObj obj) {
     return true;
 }
 
+int64_t DeferredWriter::getDroppedEntries() {
+    return _droppedEntries;
+}
+
+
 }  // namespace mongo