NODE-507 Repeatedly Switching DBs on a single connection increases memory usage

Author: christkv

lib/db.js

@@ -99,6 +99,8 @@ var Db = function(databaseName, topology, options) {
   this.s = {
     // Database name
       databaseName: databaseName
+    // DbCache
+    , dbCache: {}
     // Children db's
     , children: []
     // Topology
@@ -123,6 +125,8 @@ var Db = function(databaseName, topology, options) {
     , nativeParser: options.nativeParser || options.native_parser
     // Promise library
     , promiseLibrary: promiseLibrary
+    // No listener
+    , noListener: typeof options.noListener == 'boolean' ? options.noListener : false
   }
 
   // Ensure we have a valid db name
@@ -180,6 +184,7 @@ var Db = function(databaseName, topology, options) {
 
   // This is a child db, do not register any listeners
   if(options.parentDb) return;
+  if(this.s.noListener) return;
 
   // Add listeners
   topology.once('error', createListener(self, 'error', self));
@@ -968,24 +973,40 @@ Db.prototype.addChild = function(db) {
  * Create a new Db instance sharing the current socket connections.
  * @method
  * @param {string} name The name of the database we want to use.
+ * @param {object} [options=null] Optional settings.
+ * @param {boolean} [options.noListener=false] Do not make the db an event listener to the original connection.
  * @return {Db}
  */
-Db.prototype.db = function(dbName) {
+Db.prototype.db = function(dbName, options) {
+  options = options || {};
   // Copy the options and add out internal override of the not shared flag
-  var options = {};
   for(var key in this.options) {
     options[key] = this.options[key];
   }
 
+  // Do we have the db in the cache already
+  if(this.s.dbCache[dbName]) {
+    return this.s.dbCache[dbName];
+  }
+
   // Add current db as parentDb
-  options.parentDb = this;
+  if(options.noListener == null || options.noListener == false) {
+    options.parentDb = this;
+  }
+
   // Add promiseLibrary
   options.promiseLibrary = this.s.promiseLibrary;
 
   // Return the db object
   var db = new Db(dbName, this.s.topology, options)
+
   // Add as child
-  this.addChild(db);
+  if(options.noListener == null || options.noListener == false) {
+    this.addChild(db);
+  }
+
+  // Add the db to the cache
+  this.s.dbCache[dbName] = db;
   // Return the database
   return db;
 };

test/functional/insert_tests.js

@@ -572,9 +572,6 @@ exports.shouldThrowErrorIfSerializingFunctionUnOrdered = {
       collection.insert({i:1, z:func }, {w:1, serializeFunctions:true, ordered:false}, function(err, result) {
         test.equal(null, err);
 
-        console.log("--------------------------------- 0")
-        console.dir(result)
-
         collection.findOne({_id:result.ops[0]._id}, function(err, object) {
           console.dir(object)
           test.equal(func.toString(), object.z.code);

test/functional/multiple_db_tests.js

@@ -7,7 +7,7 @@ exports.shouldCorrectlyEmitErrorOnAllDbsOnPoolClose = {
   // Add a tag that our runner can trigger on
   // in this case we are setting that node needs to be higher than 0.10.X to run
   metadata: { requires: {topology: 'single'} },
-  
+
   // The actual test we wish to run
   test: function(configuration, test) {
     if(process.platform !== 'linux') {
@@ -22,7 +22,7 @@ exports.shouldCorrectlyEmitErrorOnAllDbsOnPoolClose = {
       db.on("close", function(err) {
         numberOfCloses = numberOfCloses + 1;
       })
-      
+
       db.open(function(err, db) {
         db.createCollection('shouldCorrectlyErrorOnAllDbs', function(err, collection) {
           test.equal(null, err);
@@ -49,7 +49,7 @@ exports.shouldCorrectlyEmitErrorOnAllDbsOnPoolClose = {
             db.close();
           });
         });
-      });      
+      });
     } else {
       test.done();
     }
@@ -58,12 +58,12 @@ exports.shouldCorrectlyEmitErrorOnAllDbsOnPoolClose = {
 
 /**
  * Test the auto connect functionality of the db
- * 
+ *
  * @ignore
  */
 exports.shouldCorrectlyUseSameConnectionsForTwoDifferentDbs = {
   metadata: { requires: { topology: ['single', 'replicaset', 'sharded', 'ssl', 'heap', 'wiredtiger'] } },
-  
+
   // The actual test we wish to run
   test: function(configuration, test) {
     var client = configuration.newDbInstance({w:1}, {poolSize:1});
@@ -77,7 +77,7 @@ exports.shouldCorrectlyUseSameConnectionsForTwoDifferentDbs = {
         var secondDb = client.db(configuration.db_name + "_2");
         secondDb.createCollection('shouldCorrectlyUseSameConnectionsForTwoDifferentDbs', function(err, collection) {
           // Insert a dummy document
-          collection.insert({a:20}, {safe: true}, function(err, r) {            
+          collection.insert({a:20}, {safe: true}, function(err, r) {
             test.equal(null, err);
 
             // Query it
@@ -87,21 +87,21 @@ exports.shouldCorrectlyUseSameConnectionsForTwoDifferentDbs = {
               // Use the other db
               client.createCollection('shouldCorrectlyUseSameConnectionsForTwoDifferentDbs', function(err, collection) {
                 // Insert a dummy document
-                collection.insert({b:20}, {safe: true}, function(err, r) {            
-                  test.equal(null, err);            
+                collection.insert({b:20}, {safe: true}, function(err, r) {
+                  test.equal(null, err);
 
                   // Query it
                   collection.findOne({}, function(err, item) {
                     test.equal(20, item.b);
 
                     test.equal(null, err);
                     client.close();
-                    second_test_database.close();            
-                    test.done();                
-                  });              
+                    second_test_database.close();
+                    test.done();
+                  });
                 });
               });
-            });              
+            });
           });
         });
       });
@@ -114,7 +114,7 @@ exports.shouldCorrectlyUseSameConnectionsForTwoDifferentDbs = {
  */
 exports.shouldCorrectlyHandleMultipleDbsFindAndModifies = {
   metadata: { requires: { topology: ['single', 'replicaset', 'sharded', 'ssl', 'heap', 'wiredtiger'] } },
-  
+
   // The actual test we wish to run
   test: function(configuration, test) {
     var db = configuration.newDbInstance({w:1}, {poolSize:1});
@@ -138,10 +138,10 @@ exports.shouldCorrectlyHandleMultipleDbsFindAndModifies = {
  */
 exports['should not leak listeners'] = {
   metadata: { requires: { topology: ['single', 'replicaset', 'sharded', 'ssl', 'heap', 'wiredtiger'] } },
-  
+
   // The actual test we wish to run
   test: function(configuration, test) {
-    var MongoClient = configuration.require.MongoClient;     
+    var MongoClient = configuration.require.MongoClient;
     MongoClient.connect(configuration.url(), function(err, db) {
       for (var i = 0; i < 100; i++) {
         db.db("test");
@@ -151,4 +151,4 @@ exports['should not leak listeners'] = {
       test.done();
     });
   }
-}
+}