http.js: util.inspect() called even when debug is off.

[bgaff]

When process.env.NODE_DEBUG is not defined, then in lib/http.js the debug function is defined as function () { } (line 35). Nonetheless, in OutgoingMessage.prototype.write it calls debug as: debug('string chunk = ' + util.inspect(chunk)) (line 612), thus even when debug is disabled util.inspect() is being called, after profiling I found that my application was spending a considerable amount of time in util.inspect(). Fixing this bug resulted in a considerable performance improvement.

[isaacs]

Are you running node_g? I thought that the debug() calls were stripped out by a macro in the non-debug binary builds?

[koichik]

@isaacs - since v0.4.8, debug statements has been enabled in normal build (c409aab).

[isaacs]

Oh, I see. Then this is a valid issue.

[ry]

Benching version 5e37e10. Applied this change to http_simple.js to avoid hot path

diff --git a/benchmark/http_simple.js b/benchmark/http_simple.js
index 8d66190..8dbbf06 100644
--- a/benchmark/http_simple.js
+++ b/benchmark/http_simple.js
@@ -85,8 +85,8 @@ var server = http.createServer(function (req, res) {

   res.writeHead(status, { "Content-Type": "text/plain",
                           "Content-Length": content_length });
-  res.end(body);
-
+  res.write(body);
+  res.end();
 });

 server.listen(port, function () {

ab -t 10 -c 1 http://127.0.0.1:8000/bytes/12345 | grep Req

With fix:
1814.68
1817.17
1814.15

Without fix:
1808.33
1811.59
1824.45