nodejs response speed and nginx - node.js

Question

Just started testing nodejs, and wanted to get some help in understanding following behavior:
Example #1:
var http = require('http');
http.createServer(function(req, res){
res.writeHeader(200, {'Content-Type': 'text/plain'});
res.end('foo');
}).listen(1001, '0.0.0.0');
Example #2:
var http = require('http');
http.createServer(function(req, res){
res.writeHeader(200, {'Content-Type': 'text/plain'});
res.write('foo');
res.end('bar');
}).listen(1001, '0.0.0.0');
When testing response time in Chrome:
example #1 - 6-10ms
example #2 - 200-220ms
But, if test both examples through nginx proxy_pass
server{
listen 1011;
location / {
proxy_pass http://127.0.0.1:1001;
}
}
i get this:
example #1 - 4-8ms
example #2 - 4-8ms
I am not an expert on either nodejs or nginx, and asking if someone can explain this?
nodejs - v.0.8.1
nginx - v.1.2.2
update:
thanks to Hippo, i made test with ab on my server with and without nginx,
and got opposite results.
also added to nginx config proxy_cache off
server{
listen 1011;
location / {
proxy_pass http://127.0.0.1:1001;
proxy_cache off;
}
}
example #1 direct:
ab -n 1000 -c 50 http:// 127.0.0.1:1001/
Server Software:
Server Hostname: 127.0.0.1
Server Port: 1001
Document Path: /
Document Length: 65 bytes
Concurrency Level: 50
Time taken for tests: 1.018 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Total transferred: 166000 bytes
HTML transferred: 65000 bytes
Requests per second: 981.96 [#/sec] (mean)
Time per request: 50.919 [ms] (mean)
Time per request: 1.018 [ms] (mean, across all concurrent requests)
Transfer rate: 159.18 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.6 0 3
Processing: 0 50 44.9 19 183
Waiting: 0 49 44.8 17 183
Total: 1 50 44.7 19 183
example #1 nginx:
ab -n 1000 -c 50 http:// 127.0.0.1:1011/
Server Software: nginx/1.2.2
Server Hostname: 127.0.0.1
Server Port: 1011
Document Path: /
Document Length: 65 bytes
Concurrency Level: 50
Time taken for tests: 1.609 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Total transferred: 187000 bytes
HTML transferred: 65000 bytes
Requests per second: 621.40 [#/sec] (mean)
Time per request: 80.463 [ms] (mean)
Time per request: 1.609 [ms] (mean, across all concurrent requests)
Transfer rate: 113.48 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.6 0 3
Processing: 2 77 44.9 96 288
Waiting: 2 77 44.8 96 288
Total: 3 78 44.7 96 288
example #2 direct:
ab -n 1000 -c 50 http:// 127.0.0.1:1001/
Server Software:
Server Hostname: 127.0.0.1
Server Port: 1001
Document Path: /
Document Length: 76 bytes
Concurrency Level: 50
Time taken for tests: 1.257 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Total transferred: 177000 bytes
HTML transferred: 76000 bytes
Requests per second: 795.47 [#/sec] (mean)
Time per request: 62.856 [ms] (mean)
Time per request: 1.257 [ms] (mean, across all concurrent requests)
Transfer rate: 137.50 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.3 0 2
Processing: 0 60 47.8 88 193
Waiting: 0 60 47.8 87 193
Total: 0 61 47.7 88 193
example #2 nginx:
ab -n 1000 -c 50 http:// 127.0.0.1:1011/
Server Software: nginx/1.2.2
Server Hostname: 127.0.0.1
Server Port: 1011
Document Path: /
Document Length: 76 bytes
Concurrency Level: 50
Time taken for tests: 1.754 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Total transferred: 198000 bytes
HTML transferred: 76000 bytes
Requests per second: 570.03 [#/sec] (mean)
Time per request: 87.715 [ms] (mean)
Time per request: 1.754 [ms] (mean, across all concurrent requests)
Transfer rate: 110.22 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.4 0 2
Processing: 1 87 42.1 98 222
Waiting: 1 86 42.3 98 222
Total: 1 87 42.0 98 222
Now results looks more logic, but still there is a strange delay when calling res.write()
I guess it was (sure looks like) a stupid question, but i still get huge difference in response time in browser with this server configuration (Centos 6) and this concrete server (vps).
On my home computer (Ubuntu 12) but with older versions testing from localhost everything works fine.

Answer 1

Peeking into http.js reveals that case #1 has special handling in nodejs itself, some kind of a shortcut optimization I guess.
var hot = this._headerSent === false &&
typeof(data) === 'string' &&
data.length > 0 &&
this.output.length === 0 &&
this.connection &&
this.connection.writable &&
this.connection._httpMessage === this;
if (hot) {
// Hot path. They're doing
// res.writeHead();
// res.end(blah);
// HACKY.
if (this.chunkedEncoding) {
var l = Buffer.byteLength(data, encoding).toString(16);
ret = this.connection.write(this._header + l + CRLF +
data + '\r\n0\r\n' +
this._trailer + '\r\n', encoding);
} else {
ret = this.connection.write(this._header + data, encoding);
}
this._headerSent = true;
} else if (data) {
// Normal body write.
ret = this.write(data, encoding);
}
if (!hot) {
if (this.chunkedEncoding) {
ret = this._send('0\r\n' + this._trailer + '\r\n'); // Last chunk.
} else {
// Force a flush, HACK.
ret = this._send('');
}
}
this.finished = true;

Answer 2

I've took you examples files and used ab (Apache Benchmark) as a proper tool for benchmarking HTTP server performance:
Example 1:
Concurrency Level: 50
Time taken for tests: 0.221 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Total transferred: 104000 bytes
HTML transferred: 3000 bytes
Requests per second: 4525.50 [#/sec] (mean)
Time per request: 11.049 [ms] (mean)
Time per request: 0.221 [ms] (mean, across all concurrent requests)
Transfer rate: 459.62 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.7 0 4
Processing: 1 11 6.4 10 32
Waiting: 1 11 6.4 10 32
Total: 1 11 6.7 10 33
Example 2:
Concurrency Level: 50
Time taken for tests: 0.256 seconds
Complete requests: 1000
Failed requests: 0
Write errors: 0
Total transferred: 107000 bytes
HTML transferred: 6000 bytes
Requests per second: 3905.27 [#/sec] (mean)
Time per request: 12.803 [ms] (mean)
Time per request: 0.256 [ms] (mean, across all concurrent requests)
Transfer rate: 408.07 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.6 0 4
Processing: 1 12 7.0 12 34
Waiting: 1 12 6.9 12 34
Total: 1 12 7.1 12 34
Note:
The second example is as fast as the first one. The small differences are probably caused by the the additional function call in the code and the fact that the document size is larger then with the first one.