Issue with Node 4.x when receiving pipelined reqeusts

[DamianEdwards]

After updating to Node 4.x from 0.12.x, benchmarking by sending pipelining requests results in an initial spike of requests followed by no requests being processed on those connections, and those connections remaining open even after the load generator client finishes (connection leak). The same behavior does not occur when not pipelining requests, and it doesn't occur on 0.10.x or 0.12.x at all. The issue reproduces on both Linux and Windows.

I'm generating load using "wrk" (from a remote Linux machine) and the app is the benchmark app from the TechEmpower benchmarks.

[rmg]

@DamianEdwards which specific version? v4.2.0? v4.1.2?

[DamianEdwards]

I reproduced on both 4.1.2 and 4.2.0

[brendanashworth]

Does it occur on 4.1.1? There were a few changes in 4.1.2 (0504066, b3d9678) that might be causing this.

[DamianEdwards]

I'll drop back to 4.1.1 tomorrow and try it out.

[Fishrock123]

cc @indutny

[indutny]

@DamianEdwards does removing those lines help?

• https://github.com/nodejs/node/blob/master/lib/_http_server.js#L273-L274
• https://github.com/nodejs/node/blob/master/lib/_http_server.js#L459

[indutny]

Actually, latter one should be enough to verify it.

[DamianEdwards]

@indutny I'm assuming I have to build from source to try out removing that line?

[indutny]

@DamianEdwards yeah. Sorry, I forgot to mention it.

[DamianEdwards]

@indutny 😄
I'll see what I can do. That change was added in 4.1.2?

[indutny]

Yep.

[indutny]

Found one bug, already:

diff --git a/lib/_http_outgoing.js b/lib/_http_outgoing.js
index 6650c06..366c516 100644
--- a/lib/_http_outgoing.js
+++ b/lib/_http_outgoing.js
@@ -663,6 +663,9 @@ OutgoingMessage.prototype._flush = function() {
       this.output = [];
       this.outputEncodings = [];
       this.outputCallbacks = [];
+      if (this._onPendingData !== null)
+        this._onPendingData(-this.outputSize);
+      this.outputSize = 0;
     }

     if (this.finished) {

Looking for more.

[indutny]

Second part of issue is handling of paused parser in consumed socket. Working on fix.

[indutny]

Full fix:

diff --git a/lib/_http_outgoing.js b/lib/_http_outgoing.js
index 6650c06..366c516 100644
--- a/lib/_http_outgoing.js
+++ b/lib/_http_outgoing.js
@@ -663,6 +663,9 @@ OutgoingMessage.prototype._flush = function() {
       this.output = [];
       this.outputEncodings = [];
       this.outputCallbacks = [];
+      if (this._onPendingData !== null)
+        this._onPendingData(-this.outputSize);
+      this.outputSize = 0;
     }

     if (this.finished) {
diff --git a/lib/_http_server.js b/lib/_http_server.js
index c11d369..ffaa0b8 100644
--- a/lib/_http_server.js
+++ b/lib/_http_server.js
@@ -270,6 +270,7 @@ function connectionListener(socket) {
     // need to pause TCP socket/HTTP parser, and wait until the data will be
     // sent to the client.
     outgoingData += delta;
+    console.log(outgoingData);
     if (socket._paused && outgoingData < socket._writableState.highWaterMark)
       return socketOnDrain();
   }
@@ -405,6 +406,7 @@ function connectionListener(socket) {
     if (socket._paused) {
       // onIncoming paused the socket, we should pause the parser as well
       debug('pause parser');
+      parser.unconsume(socket._handle._externalStream);
       socket.parser.pause();
     }
   }

@DamianEdwards may I ask you to give it a try?