zlib: release callback and buffer after processing

PR-URL: #6955 Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: Yuval Brik <[email protected]>

Author: mdlavin

lib/zlib.js

@@ -560,6 +560,16 @@ Zlib.prototype._processChunk = function(chunk, flushFlag, cb){
 req.callback=callback;
 
 functioncallback(availInAfter,availOutAfter){
+// When the callback is used in an async write, the callback's
+// context is the `req` object that was created. The req object
+// is === this._handle, and that's why it's important to null
+// out the values after they are done being used. `this._handle`
+// can stay in memory longer than the callback and buffer are needed.
+if(this){
+this.buffer=null;
+this.callback=null;
+}
+
 if(self._hadError)
 return;