http: reset parser.incoming when server request is finished

This resolves a memory leak for keep-alive connections and does not
regress in the way that 779a05d5d1bfe2eeb05386f did by waiting for
the incoming request to be finished before releasing the
`parser.incoming` object.

Refs: https://github.com/nodejs/node/pull/28646
Refs: https://github.com/nodejs/node/pull/29263
Fixes: https://github.com/nodejs/node/issues/9668

PR-URL: https://github.com/nodejs/node/pull/29297
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/lib/_http_server.js b/lib/_http_server.js
index 862b7c970b..6dc29c855e 100644
--- a/lib/_http_server.js
+++ b/lib/_http_server.js
@@ -611,6 +611,19 @@ function onParserExecuteCommon(server, socket, parser, state, ret, d) {
   }
 }
 
+function clearIncoming(req) {
+  req = req || this;
+  const parser = req.socket && req.socket.parser;
+  // Reset the .incoming property so that the request object can be gc'ed.
+  if (parser && parser.incoming === req) {
+    if (req.readableEnded) {
+      parser.incoming = null;
+    } else {
+      req.on('end', clearIncoming);
+    }
+  }
+}
+
 function resOnFinish(req, res, socket, state, server) {
   // Usually the first incoming element should be our request.  it may
   // be that in the case abortIncoming() was called that the incoming
@@ -618,6 +631,7 @@ function resOnFinish(req, res, socket, state, server) {
   assert(state.incoming.length === 0 || state.incoming[0] === req);
 
   state.incoming.shift();
+  clearIncoming(req);
 
   // If the user never called req.read(), and didn't pipe() or
   // .resume() or .on('data'), then we call req._dump() so that the