SERVER-24194 - Backport, change the dropAllQueued loop to avoid duplicating work over many threads

3 files changed, 36 insertions, 36 deletions

diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
index 23db7e6b14a..26406288303 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.cpp
@@ -532,8 +532,8 @@ bool WiredTigerKVEngine::_drop(StringData ident) {
 
     WiredTigerSession session(_conn);
 
-    int ret =
-        session.getSession()->drop(session.getSession(), uri.c_str(), "force,lock_wait=false");
+    int ret = session.getSession()->drop(
+        session.getSession(), uri.c_str(), "force,checkpoint_wait=false");
     LOG(1) << "WT drop of  " << uri << " res " << ret;
 
     if (ret == 0) {
@@ -545,7 +545,7 @@ bool WiredTigerKVEngine::_drop(StringData ident) {
         // this is expected, queue it up
         {
             stdx::lock_guard<stdx::mutex> lk(_identToDropMutex);
-            _identToDrop.insert(uri);
+            _identToDrop.push(uri);
         }
         _sessionCache->closeAll();
         return false;
@@ -565,7 +565,7 @@ bool WiredTigerKVEngine::haveDropsQueued() const {
     }
 
     // We only want to check the queue max once per second or we'll thrash
-    // This is done in haveDropsQueued, not dropAllQueued so we skip the mutex
+    // This is done in haveDropsQueued, not dropSomeQueuedIdents so we skip the mutex
     if (delta < Milliseconds(1000))
         return false;
 
@@ -574,41 +574,40 @@ bool WiredTigerKVEngine::haveDropsQueued() const {
     return !_identToDrop.empty();
 }
 
-void WiredTigerKVEngine::dropAllQueued() {
-    set<string> mine;
-    {
-        stdx::lock_guard<stdx::mutex> lk(_identToDropMutex);
-        mine = _identToDrop;
-    }
+void WiredTigerKVEngine::dropSomeQueuedIdents() {
+    int numInQueue;
 
-    set<string> deleted;
+    WiredTigerSession session(_conn);
 
     {
-        WiredTigerSession session(_conn);
-        for (set<string>::const_iterator it = mine.begin(); it != mine.end(); ++it) {
-            string uri = *it;
-            int ret = session.getSession()->drop(
-                session.getSession(), uri.c_str(), "force,lock_wait=false");
-            LOG(1) << "WT queued drop of  " << uri << " res " << ret;
-
-            if (ret == 0) {
-                deleted.insert(uri);
-                continue;
-            }
+        stdx::lock_guard<stdx::mutex> lk(_identToDropMutex);
+        numInQueue = _identToDrop.size();
+    }
 
-            if (ret == EBUSY) {
-                // leave in qeuue
-                continue;
-            }
+    int numToDelete = 10;
+    int tenPercentQueue = numInQueue * 0.1;
+    if (tenPercentQueue > 10)
+        numToDelete = tenPercentQueue;
 
-            invariantWTOK(ret);
+    LOG(1) << "WT Queue is: " << numInQueue << " attempting to drop: " << numToDelete << " tables";
+    for (int i = 0; i < numToDelete; i++) {
+        string uri;
+        {
+            stdx::lock_guard<stdx::mutex> lk(_identToDropMutex);
+            if (_identToDrop.empty())
+                break;
+            uri = _identToDrop.front();
+            _identToDrop.pop();
         }
-    }
+        int ret = session.getSession()->drop(
+            session.getSession(), uri.c_str(), "force,checkpoint_wait=false");
+        LOG(1) << "WT queued drop of  " << uri << " res " << ret;
 
-    {
-        stdx::lock_guard<stdx::mutex> lk(_identToDropMutex);
-        for (set<string>::const_iterator it = deleted.begin(); it != deleted.end(); ++it) {
-            _identToDrop.erase(*it);
+        if (ret == EBUSY) {
+            stdx::lock_guard<stdx::mutex> lk(_identToDropMutex);
+            _identToDrop.push(uri);
+        } else {
+            invariantWTOK(ret);
         }
     }
 }
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h
index 9028970123b..8c5a54f6bb4 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h
@@ -31,7 +31,7 @@
 
 #pragma once
 
-#include <set>
+#include <queue>
 #include <string>
 
 #include <wiredtiger.h>
@@ -132,7 +132,7 @@ public:
     WT_CONNECTION* getConnection() {
         return _conn;
     }
-    void dropAllQueued();
+    void dropSomeQueuedIdents();
     bool haveDropsQueued() const;
 
     void syncSizeInfo(bool sync) const;
@@ -175,8 +175,9 @@ private:
     std::string _rsOptions;
     std::string _indexOptions;
 
+    mutable stdx::mutex _dropAllQueuesMutex;
     mutable stdx::mutex _identToDropMutex;
-    std::set<std::string> _identToDrop;
+    std::queue<std::string> _identToDrop;
 
     mutable Date_t _previousCheckedDropsQueued;
 
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.cpp
index 6f27a7bb6d9..6619ce01865 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.cpp
@@ -288,7 +288,7 @@ void WiredTigerSessionCache::releaseSession(WiredTigerSession* session) {
         delete session;
 
     if (_engine && _engine->haveDropsQueued())
-        _engine->dropAllQueued();
+        _engine->dropSomeQueuedIdents();
 }
 
 void WiredTigerSessionCache::setJournalListener(JournalListener* jl) {