Here Be Dragons: PHP at Its Limits.

PHP application frameworks come with many well known benefits. The Request-Response structure exposed by many of these frameworks also gives us the opportunity to reduce overheads in our applications significantly. By using PHPFastCGI and the Speedfony Bundle - you can take a simple application from 250 rq/s to over 2200 rq/s. This talk gives a brief overview of the process, the dragons and the rewards.

Transcript

1. Here Be Dragons
   PHP at Its Limits
   Presentation by Andrew Carter
   @AndrewCarterUK
   http://github.com/AndrewCarterUK
   http://github.com/PHPFastCGI
   

   View Slide

2. What do we need for a web application?
   ●
   We need a web server – something to serve our
   application to the outside world
   ●
   Our application is a 'function'. It takes an input
   and produces an output... Response = F ( Request )
   ●
   We need some way to write this 'function' and tell
   our web server about it!
   

   View Slide

3. CGI: Common Gateway Interface
   ●
   When a request comes in, a program is started with a
   series of environment variables
   REQUEST_URI, REQUEST_METHOD, SERVER_ADDR, ...
   ●
   What the executable prints out is sent as the response
   ●
   At least one new process per request
   ●
   Can use any language to make our application
   

   View Slide

4. CGI and PHP
   ●
   Originally PHP was a CGI program
   ●
   Server modules are now more common
   ●
   Even with 'mod_php', each apache worker thread
   needs to load the PHP interpreter
   ●
   Enter FastCGI...
   

   View Slide

5. ●
   FastCGI applications run as a server/daemon.
   ●
   FastCGI applications receive the same variables
   and send the same response as a CGI
   application - but over a local connection.
   ●
   One process can handle many requests!
   

   View Slide

6. PHP-FPM
   ●
   PHP-FPM uses FastCGI
   ●
   Don't need to load the PHP interpreter for each
   request
   ●
   But PHP still has to reload our application
   for each request. We can do better...
   

   View Slide

7. Legacy PHP Applications
   How could we 'daemonize' this script?
   We could use output buffering? But it's hard to see how a third party
   piece of software could do this without a fixed application structure...
   

   View Slide

8. Request-Response Frameworks
   How could we 'daemonize' this script?
   All we need to do is set up the kernel, create a 'Request' object for
   each request and relay the returned response.
   

   View Slide

9. Dragons!!!
   Can you think of any dangers?
   

   View Slide

10. Dragon #1
    ●
    PHP isn't designed to live for very long
    ●
    Applications tend to be quite careless about
    memory allocation
    ●
    Long running PHP scripts need to be
    supervised – consider restarting process after
    'N' requests have been served
    

    View Slide

11. Dragon #2
    ●
    Static memory is now shared between requests
    ●
    Previously all the memory accessible from our
    application was limited to the current request scope
    ●
    This is no longer true – we have to be very careful
    about static memory and application state
    

    View Slide

12. PHPFastCGI – A collection of packages...
    ●
    FastCGIDaemon
    Listens for FastCGI requests
    Listens for FastCGI requests
    ●
    SpeedfonyBundle
    Integrates the FastCGIDaemon with symfony2
    ●
    SpeedfonyBenchmarkingApp
    Simple site for speed testing
    

    View Slide

13. An alternative: PHP-PM
    

    View Slide

14. PHPFastCGI vs. PHP-PM
    ●
    Both not yet stable – don't even think about going
    near them in production!
    ●
    FastCGI applications can be process managed by
    the web server... can restart our workers without the
    web server sending out 5XX error messages
    ●
    Easier to put FastCGI applications on a shared
    server
    

    View Slide

15. Benchmarks
    1 2 3 4 5 10 15 20
    0
    500
    1000
    1500
    2000
    2500
    PHP-FPM
    PHP-PM
    PHPFastCGI
    Concurrent connections
    Requests per second
    VMWare Fusion: Ubuntu 15.04 (64 bit), 4 cores, 2 GB RAM, NGINX
    

    View Slide

16. The Future & PSR-7
    ●
    PHP extensions and web server modules could
    make this process a lot easier!
    ●
    PSR-7: Standard 'Request' and 'Response'
    objects allow for FastCGIDaemon and similar
    packages to become framework agnostic
    

    View Slide

17. Thank you for listening!
    Any questions?
    Presentation by Andrew Carter
    @AndrewCarterUK
    http://github.com/AndrewCarterUK
    http://github.com/PHPFastCGI
    

    View Slide