Fix pool leaking connections after conn.changeUser

fixes #833

Author: dougwilson

Changes.md

@@ -4,6 +4,10 @@ This file is a manually maintained list of changes for each release. Feel free
 to add your changes here when sending pull requests. Also send corrections if
 you spot any mistakes.
 
+## HEAD
+
+* Fix pool leaking connections after `conn.changeUser` #833
+
 ## v2.3.1 (2014-05-26)
 
 * Add database errors to error constants

lib/Pool.js

@@ -98,7 +98,7 @@ Pool.prototype.releaseConnection = function releaseConnection(connection) {
 
     if (connection._purge) {
       // purge connection from pool
-      this._removeConnection(connection);
+      this._purgeConnection(connection);
       return;
     } else if (this._freeConnections.indexOf(connection) !== -1) {
       // connection already in free connection pool
@@ -190,6 +190,18 @@ Pool.prototype.query = function (sql, values, cb) {
   });
 };
 
+Pool.prototype._purgeConnection = function _purgeConnection(connection) {
+  var pool = this;
+
+  connection._realEnd(function(err) {
+    if (err) {
+      connection.destroy();
+    }
+
+    pool._removeConnection(connection);
+  });
+};
+
 Pool.prototype._removeConnection = function(connection) {
   var index;
 

test/unit/pool/test-change-user-eject.js

@@ -1,44 +1,61 @@
 var assert = require('assert');
 var common = require('../../common');
 var pool   = common.createPool({
-  connectionLimit : 1,
+  connectionLimit : 2,
   user            : 'user_1',
   port            : common.fakeServerPort
 });
 
+var closed = 0;
 var server = common.createFakeServer();
 var thread = 0;
 
 server.listen(common.fakeServerPort, function(err) {
   assert.ifError(err);
 
+  var conn0;
   pool.getConnection(function(err, conn) {
     assert.ifError(err);
     assert.strictEqual(conn.threadId, 1);
-    conn.release();
+    conn0 = conn;
   });
 
   pool.getConnection(function(err, conn) {
     assert.ifError(err);
-    assert.strictEqual(conn.threadId, 1);
+    assert.strictEqual(conn.threadId, 2);
 
     conn.changeUser({user: 'user_2'}, function(err) {
       assert.ifError(err);
-      assert.strictEqual(conn.threadId, 1);
+      assert.strictEqual(conn.threadId, 2);
       conn.release();
+      conn0.release();
     });
   });
 
-  pool.getConnection(function(err, conn) {
+  pool.getConnection(function(err, conn1) {
     assert.ifError(err);
-    assert.strictEqual(conn.threadId, 2);
-    conn.destroy();
-    server.destroy();
+    assert.strictEqual(conn1.threadId, 1);
+
+    pool.getConnection(function(err, conn2) {
+      assert.ifError(err);
+      assert.strictEqual(conn2.threadId, 3);
+      conn1.release();
+      conn2.release();
+
+      pool.end(function(err) {
+        assert.ifError(err);
+        assert.strictEqual(closed, 3);
+        server.destroy();
+      });
+    });
   });
 });
 
 server.on('connection', function(incomingConnection) {
   incomingConnection.handshake({
     threadId: ++thread
   });
+  incomingConnection.on('quit', function() {
+    closed++;
+  });
 });