How to increase PHP over HTML speed?

Question

I have a PHP file that gets HTML from Memcached and serves it to user. When I test it like this:

ab -n 1000 -c 100 http://website.com/test.php

It does 22 requests per second.

But when I put the same HTML to a html file and do this test:

ab -n 1000 -c 100 http://website.com/test.html

I get like 4500 requests per second.

I need to stick to PHP because first time I need to generate HTML and next times I just get generated one from Memcached. And moreover HTML I display is different for every other user (recognized based on $_GET ['user_id'] value). Is there any way to make RPS higher? Closer to serving plain HTML?

I use as a server Lighttpd.

Answer 1

Chain of thoughts (to be continued....):
First I would test if the problem is triggered by or significantly worsened by concurrency. With your -n 1000 -c 100 test you had a ratio of 22/4500. What about -n 1000 -c 10 or -n 1000 -c 1?

Then I would try the same again + keeping track of memory consumption, disc i/o and cpu usage. Is any of this clearly the limiting factor?

Then I'd test simple php scripts:

• an empty script
• <?php echo 'x';
• no script at all, but the contents of test.html copied over to test.php
• only serving a small memcached item. As simple a script as possible, construct the memchached object and get an item, no test, no expiration, no add, only echo $mc->get(string $key)

How do those compare to test.html?

edit:

Let's take Web Server Performance Comparison: LiteSpeed 2.0 VS as a comparison point. The benchmark was performed "for" another "rivaling" webserver product but for the moment let's assume they weren't (too) biased ;-)

They had a

• CPU: Single Intel Xeon 2.4GHz/533FSB/512KB L2 Cache
• memory: 256MB ECC PC2700
• Hard Drive: 36GB 10K RPM SCSI drive Seagate ST336607LW
• NIC: on board Intel PRO/1000 Gigabit Adapter

The lighthttpd served 15475/s files of 100 bytes, 1593/s helloworld.php and 399/s phpinfo.php scripts (both fastcgi). That's a ration of ~ 1:10 (hello world) or 1:40 (phpinfo). "Your" ratio is 22:4500 ~ 1:200. And even stranger it doesn't change when the script changes. Your "real" script or an empty php script, no matter always 1:22. That raises the "strangeness factor" quite a bit (even though the tests are not identical).
First of all I would double-check if php was compiled with fastcgi-support, see http://www.fastcgi.com/docs/faq.html#PHP. Then I'd test "my" lighthttpd with a simple c/c++ fastcgi program as mentioned in the test, a real simple "hello world". There's an example at http://www.fastcgi.com/devkit/doc/fastcgi-prog-guide/ch2c.htm#4263. If this scales "well", i.e. significantly better than your php-fastcgi, I'd try it with a "barely running" php version, i.e. compiled with --disable-all and only those modules (re)actived and built-in that are necessary to start php and let it print "hello world". Also use the default php.ini. Does this change anything?

Answer 2

You could try (psuedo code):

if file myfilecache/$user_$request_$today.html does not exist 
then do
     format page 
     write page to myfilecache/$user_$request_$today.html
done
redirect to myfilecache/$user_$request_$today.html

The file system makes is a pretty good cache and lightpd will do the actual work of serving up the page.

Answer 3

Going faster than script? Try writing plain html files and serving those. And make an "updater" script that updates your html files from time to time, or on a certain event if you really need speed like that.

Try using SSI in some places and see how that works out (http://httpd.apache.org/docs/1.3/howto/ssi.html)

Try using Eaccelerator (http://eaccelerator.net/ ) or APC (http://www.php.net/apc/) to speed up the script parser, but it wont do wonders on PHP5...

Make sure the physical server has enough free resources (FAST hdd, lots of ram, multiple-processors).

Its pretty normal that your script is slower than the html page:) Serving up the html page means a simple copy-of-the-file-over-the-wire. The php script means initializing the script engine, caching, parsing classes, functions, memory allocations, session locking/unlocking and saving, reading from the memcached server, reading config files.... for each of the requests...

Answer 4

You might also want to consider putting a HTTP cache in front of your PHP server. This will reduce the load on your web server and will handle the re-sending of previously rendered pages for you.

See Varnish for example. Another option is Squid

Obviously these are not options if you are on shared hosting - in that case rendering to .html files is a great solution.