http: remove stale timeout listeners

In order to prevent a memory leak when using keep alive, ensure that the
timeout listener for the request is removed when the response has ended.
PR-URL: #9440
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: Karl Böhlmark

lib/_http_client.js

@@ -563,7 +563,13 @@ function tickOnSocket(req, socket) {
 socket.on('close',socketCloseListener);
 
 if(req.timeout){
-socket.once('timeout',()=>req.emit('timeout'));
+constemitRequestTimeout=()=>req.emit('timeout');
+socket.once('timeout',emitRequestTimeout);
+req.once('response',(res)=>{
+res.once('end',()=>{
+socket.removeListener('timeout',emitRequestTimeout);
+});
+});
 }
 req.emit('socket',socket);
 }

test/parallel/test-http-client-timeout-option-listeners.js

@@ -0,0 +1,44 @@
+'use strict';
+constcommon=require('../common');
+consthttp=require('http');
+constassert=require('assert');
+
+constagent=newhttp.Agent({keepAlive: true});
+
+constserver=http.createServer((req,res)=>{
+res.end('');
+});
+
+constoptions={
+ agent,
+method: 'GET',
+port: undefined,
+host: common.localhostIPv4,
+path: '/',
+timeout: common.platformTimeout(100)
+};
+
+server.listen(0,options.host,common.mustCall(()=>{
+options.port=server.address().port;
+doRequest(common.mustCall((numListeners)=>{
+assert.strictEqual(numListeners,1);
+doRequest(common.mustCall((numListeners)=>{
+assert.strictEqual(numListeners,1);
+server.close();
+agent.destroy();
+}));
+}));
+}));
+
+functiondoRequest(cb){
+http.request(options,common.mustCall((response)=>{
+constsockets=agent.sockets[`${options.host}:${options.port}:`];
+assert.strictEqual(sockets.length,1);
+constsocket=sockets[0];
+constnumListeners=socket.listeners('timeout').length;
+response.resume();
+response.once('end',common.mustCall(()=>{
+process.nextTick(cb,numListeners);
+}));
+})).end();
+}