fix for connection leak

lib/dialects/mysql/connector-manager.js

@@ -14,6 +14,8 @@ module.exports = (function() {
   }
   Utils._.extend(ConnectorManager.prototype, require("../connector-manager").prototype)
 
+  var isConnecting = false
+
   ConnectorManager.prototype.query = function(sql, callee, options) {
     if(!this.isConnected) this.connect()
 
@@ -29,7 +31,10 @@ module.exports = (function() {
 
   ConnectorManager.prototype.connect = function() {
     var self = this
-
+    // in case database is slow to connect, prevent orphaning the client
+    if (this.isConnecting) {
+      return
+    }
     this.client = require("mysql").createClient({
       user: this.config.username,
       password: this.config.password,
@@ -39,11 +44,13 @@ module.exports = (function() {
     })
 
    this.client.setMaxListeners(this.maxConcurrentQueries)
+   this.isConnecting = false
   }
 
   ConnectorManager.prototype.disconnect = function() {
     var self = this
     this.client.end(function() {
+      // needed to prevent mysql connection leak
       self.client.destroy()
       self.client = null
     })