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Here Be Dragons: PHP at Its Limits.

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.

Andrew Carter

May 20, 2015

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  1. Here Be Dragons
    PHP at Its Limits
    Presentation by Andrew Carter

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  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!

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  3. CGI: Common Gateway Interface

    When a request comes in, a program is started with a
    series of environment variables

    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

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  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...

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  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!

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  6. PHP-FPM

    PHP-FPM uses FastCGI

    Don't need to load the PHP interpreter for each

    But PHP still has to reload our application
    for each request. We can do better...

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  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...

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  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.

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

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  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

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  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

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  12. PHPFastCGI – A collection of packages...

    Listens for FastCGI requests
    Listens for FastCGI requests

    Integrates the FastCGIDaemon with symfony2

    Simple site for speed testing

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  13. An alternative: PHP-PM

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  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

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  15. Benchmarks
    1 2 3 4 5 10 15 20
    Concurrent connections
    Requests per second
    VMWare Fusion: Ubuntu 15.04 (64 bit), 4 cores, 2 GB RAM, NGINX

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  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

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  17. Thank you for listening!
    Any questions?
    Presentation by Andrew Carter

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