http: free listeners on free sockets

Reduced memory usage by ensuring free sockets don't have extra
listeners while in the pool.
PR-URL: #29259
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: ronag

lib/_http_client.js

@@ -612,6 +612,8 @@ function responseKeepAlive(req) {
 }
 socket.removeListener('close',socketCloseListener);
 socket.removeListener('error',socketErrorListener);
+socket.removeListener('data',socketOnData);
+socket.removeListener('end',socketOnEnd);
 socket.once('error',freeSocketErrorListener);
 // There are cases where _handle === null. Avoid those. Passing null to
 // nextTick() will call getDefaultTriggerAsyncId() to retrieve the id.

test/parallel/test-http-agent-keepalive.js

@@ -140,9 +140,21 @@ server.listen(0, common.mustCall(() => {
 
 // Check for listener leaks when reusing sockets.
 functioncheckListeners(socket){
-assert.strictEqual(socket.listenerCount('data'),1);
-assert.strictEqual(socket.listenerCount('drain'),1);
+constcallback=common.mustCall(()=>{
+if(!socket.destroyed){
+assert.strictEqual(socket.listenerCount('data'),0);
+assert.strictEqual(socket.listenerCount('drain'),0);
+// Sockets have freeSocketErrorListener.
+assert.strictEqual(socket.listenerCount('error'),1);
+// Sockets have onReadableStreamEnd.
+assert.strictEqual(socket.listenerCount('end'),1);
+}
+
+socket.off('free',callback);
+socket.off('close',callback);
+});
 assert.strictEqual(socket.listenerCount('error'),1);
-// Sockets have onReadableStreamEnd.
 assert.strictEqual(socket.listenerCount('end'),2);
+socket.once('free',callback);
+socket.once('close',callback);
 }