From 1543c78c12658ee57fc3677a1cb0297696f94ad4 Mon Sep 17 00:00:00 2001
From: Craig Cavalier <craigcav@gmail.com>
Date: Mon, 26 Oct 2015 14:40:56 -0700
Subject: [PATCH] zlib: only apply drain listener if given callback

When stream.flush() is called without a callback, an empty listener is
being added. Since flush may be called multiple times to push SSE's
down to the client, multiple noop listeners are being added. This in
turn causes the memory leak detected message.

PR-URL: https://github.com/nodejs/node/pull/3534
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 lib/zlib.js | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/lib/zlib.js b/lib/zlib.js
index 1151b2cb88c07b..82b08018e7403e 100644
--- a/lib/zlib.js
+++ b/lib/zlib.js
@@ -444,10 +444,9 @@ Zlib.prototype.flush = function(kind, callback) {
     if (callback)
       this.once('end', callback);
   } else if (ws.needDrain) {
-    var self = this;
-    this.once('drain', function() {
-      self.flush(kind, callback);
-    });
+    if (callback) {
+      this.once('drain', () => this.flush(kind, callback));
+    }
   } else {
     this._flushFlag = kind;
     this.write(new Buffer(0), '', callback);