[DPC] Fast, Not Furious: How to identify and fix slow code

There's a saying "hardware is cheaper than developers", but this only holds true if you treat your hardware with the respect it deserves.

Learn how to diagnose, confirm and fix bottlenecks in your application using new tools like XHProf and tried and true tools like xdebug.

Also, we'll take an in-depth look at apc (advanced PHP cache) and memcache; even if you know and use memcache, this one can probably teach you a thing or two.

Transcript

1. Fast, Not Furious
   How to identify and fix slow code
   Friday, June 8, 12
   

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2. •Engineer at Engine Yard for
   Orchestra.io PHP Platform as a
   Service (PaaS)
   •Author of Zend PHP 5 Certification
   Study Guide, Sitepoints PHP
   Anthology: 101 Essential Tips, Tricks
   & Hacks & PHP Master: Write
   Cutting Edge Code
   •A contributor to Zend Framework,
   phpdoc, FRAPI and PHP internals
   •@dshafik
   •(Buy My Books!)
   Davey Shafik
   Friday, June 8, 12
   

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3. One More Thing
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4. Hard of hearing:
   PLEASE SPEAK UP!
   (Everybody Forgets This!)
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5. About These Slides
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6. About These Slides
   • Two slides per “slide”
   • Title Slide (for when I’m talking)
   • Details slide (for later)
   • Nobody likes it when you can read the slide just as
   well as the speaker can
   • I like slides that are useful
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7. Hardware is Cheap,
   Programmers are
   Expensive
   - Jeff Atwood
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8. But only if you respect
   the hardware.
   - Me
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9. Anecdote
   OR: why you shouldn’t randomly optimize
   — and why you should be careful with
   PHP 5.3’s memory garbage collection
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10. Common Causes of
    Slowdowns
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11. Common Causes of Slowdown
    1. Datastore
    • Doesn’t matter if it’s PostgreSQL, MySQL, Oracle, MongoDB,
    CouchDB, or MSSQL
    2. External Resources
    • APIs, Filesystems, Network Sockets, External Processes
    3. Bad Code
    • The only great code, is code that never has to run.
    Everything else, is just good code.
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12. Do You Have a
    Problem?
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13. Do You Have a Problem?
    • The #1 issue with performance tuning, is assuming
    you even have a problem.
    • Premature Optimization is a waste of time.
    • Determine desired performance (e.g. 100 concurrent
    users with less than 1s response times). Benchmark
    on production hardware. Do you even have a
    problem? How big?
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14. The Performance
    Loop
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15. Benchmark
    Profile
    Make
    Changes
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16. But isn’t Profiling the
    same as
    Benchmarking?
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17. Benchmarking Vs Profiling
    • Profiling Records Relative Speed + Memory Usage +
    # of calls per function + Call graph
    • The act of profiling affects the speed (the outcome) of the code
    (just like quantum physics!)
    • Benchmarking Tests Actual Speed
    • What your users actually see
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18. Profiling with xhprof
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19. Grab the tarball:
    $ wget http://pecl.php.net/get/
    xhprof-0.9.2.tgz
    $ tar –zxvf xhprof-0.9.2.tgz
    Change to the sub-directory:
    $ cd xhprof-0.9.2/extension
    Compile:
    $ ./configure --enable-xhprof
    $ make
    $ make install
    Installing xhprof
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20. Update php.ini:
    [xhprof]
    extension=xhprof.so
    xhprof.output_dir="/tmp/xhprof"
    Restart your httpd.
    Installing xhprof (cont.)
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21. Clone from git:
    $ git clone git://github.com/preinheimer/xhprof.git
    Setup the correct Database adapter:
    $ cd xhprof/xhprof_lib/utils
    $ rm xhprof_runs.php
    $ ln –s xhprof_runs_mysql.php xhprof_runs.php
    Installing xh-gui
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22. Create the Database:
    CREATE TABLE `details` (
    `id` char(17) NOT NULL, `url` varchar(255) default NULL,
    `c_url` varchar(255) default NULL,
    `timestamp` timestamp NOT NULL default CURRENT_TIMESTAMP on update
    CURRENT_TIMESTAMP,
    `server name` varchar(64) default NULL, `perfdata` MEDIUMBLOB,
    `type` tinyint(4) default NULL, `cookie` BLOB,
    `post` BLOB, `get` BLOB, `pmu` int(11) default NULL,
    `wt` int(11) default NULL, `cpu` int(11) default NULL,
    `server_id` char(3) NOT NULL default 't11',
    `aggregateCalls_include` varchar(255) DEFAULT NULL,
    PRIMARY KEY (`id`), KEY `url` (`url`), KEY `c_url` (`c_url`),
    KEY `cpu` (`cpu`), KEY `wt` (`wt`), KEY `pmu` (`pmu`),
    KEY `timestamp` (`timestamp`)
    ) ENGINE=MyISAM DEFAULT CHARSET=utf8;
    Installing xh-gui
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23. Update the config:
    $ cd .. # back up to xhprof_lib
    $ cp config.sample.php config.php
    Change these:
    $_xhprof['dbhost'] = 'localhost';
    $_xhprof['dbuser'] = 'username';
    $_xhprof['dbpass'] = 'password';
    $_xhprof['dbname'] = 'xhprof';
    $_xhprof['servername'] = 'myserver';
    $_xhprof['namespace'] = 'myapp';
    $_xhprof['url'] = 'http://url/to/xhprof/xhprof_html';
    Installing xh-gui
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24. Setup Httpd:
    Apache:
    
    ServerName xh.dev
    DocumentRoot /path/to/xhprof/xhprof_html
    
    Nginx:
    server {
    listen 80 default_server;
    server_name xh.dev;
    root /path/to/xhprof/xhprof_html;
    index index.php;
    }
    Installing xh-gui
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25. Using xhprof/xh-gui
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26. Add prepend/append config to php.ini:
    auto_prepend_file = "/path/to/xhprof/external/header.php"
    auto_append_file = "/path/to/xhprof/external/footer.php"
    OR Apache VirtualHost:
    php_admin_value auto_prepend_file /path/to/xhprof/external/header.php
    php_admin_value auto_append_file /path/to/xhprof/external/footer.php
    Using xhprof/xh-gui
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27. Demo
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28. function _urlSimilartor($url) {
    $url = preg_replace("/[0-9]+/", "XXX", $url);
    $qs = parse_url($url, PHP_URL_QUERY);
    if ($qs) {
    $parts = array();
    parse_str($qs, $parts);
    $values = array_pad(array(), sizeof($parts), "XXX");
    $normalized = array_combine(array_keys($parts), $values);
    $replace = http_build_query($normalized);
    $url = str_replace($qs, $replace, $url);
    }
    $url = preg_replace("![?&]_profile=\d!", "", $url);
    return $url;
    }
    URL Similartor
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29. Caching
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30. Key-Value Stores
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31. Key-Value Stores
    • APC
    • memcache
    • Cassandra
    • redis
    • Most NoSQL implementations (CouchDB, MongoDB,
    MemBase)
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32. Memcache
    Namespacing
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33. Namespace 1
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Namespace 2
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Memcache Namespaces
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34. Namespace 1
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Namespace 2
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Data
    Memcache Namespaces
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35. • Create a namespace key in memcache if there isn’t
    one
    • memcache_set('mynamespace', rand(1, 1000));
    • Use the namespace name, value, and the items
    unique key to create a key
    • mynamespace_189_a1773d62a609dd09e98ea1aebeddbd94
    • When you want to clear the cache, increment the
    namespace key
    • memcache_increment(‘mynamespace’);
    The Code
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36. Namespace 1
    Namespace 1.1 Namespace 1.2
    Namespace 1.3 Namespace 1.4
    Data Data Data
    Data Data Data
    Data Data Data
    Data Data Data
    Data Data Data
    Data Data Data
    Data Data Data
    Data Data Data
    Memcache Namespace Segmenting
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37. The Code
    • Create a segment key in memcache if there isn’t one
    • memcache_set('mynamespace_config', rand(1, 1000));
    • Use the namespace name, value, segment name,
    value and the items unique key to create a key
    • mynamespace_189_config_4_a609dd09e98ea1aebeddbd94
    • When you want to clear the segment cache,
    increment the segment key
    • memcache_increment(‘mynamespace_config’);
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38. example.org
    example.org_session example.org_public
    example.org_admin example.org_config
    Data Data Data
    Data Data Data
    Data Data Data
    Data Data Data
    Data Data Data
    Data Data Data
    Data Data Data
    Data Data Data
    Practical Cache Layout
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39. require_once 'Cache/Memcache.php';
    $cache = new Cache_Memcache();
    $key = $_SERVER['REQUEST_URI'];
    $data = $cache->get($key, 'blog-pages');
    if ($data !== false) {
    echo $data;
    } else {
    ob_start();
    // output all the data to the buffer
    …
    $data = ob_get_flush();
    $cache->set($key, $data, 'blog-pages');
    }
    Using The Code
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40. require_once 'Cache/Memcache.php';
    $cache = new Cache_Memcache();
    $cache->clearCache('blog-pages');
    Clearing the Cache
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41. APC
    Use it.
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42. OR: Here be dragons
    Getting Inside PHP
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43. The Worst Hello World, Ever
    class Greeting {
    public function sayHello($to)
    {
    echo "Hello $to";
    }
    }
    $greeter = new Greeting();
    $greeter->sayHello("World");
    ?>
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44. Token Name Value Token Name Value
    T_OPEN_TAG T_CLASS class }
    T_WHITESPACE T_WHITESPACE
    T_STRING Greeting }
    T_WHITESPACE T_WHITESPACE
    { T_VARIABLE $greeter
    T_WHITESPACE T_WHITESPACE
    T_PUBLIC public =
    T_WHITESPACE T_WHITESPACE
    T_FUNCTION function T_NEW new
    T_WHITESPACE T_WHITESPACE
    T_STRING sayHello T_STRING Greeting
    ( (
    T_VARIABLE $to )
    ) ;
    T_WHITESPACE T_WHITESPACE
    { T_VARIABLE $greeter
    T_WHITESPACE T_OBJECT_OPERATOR ->
    T_ECHO echo T_STRING sayHello
    T_WHITESPACE (
    " T_CONSTANT_ENCAPSED_STRING "World"
    T_ENCAPSED_AND_WHITESPACE Hello )
    T_VARIABLE $to ;
    " T_WHITESPACE
    ; T_CLOSE_TAG ?>
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45. Execution Lifecycle: PHP vs Java
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46. Execution Lifecycle with APC
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47. Installing APC
    •$ pecl install apc
    •Add: extension=apc.so to php.ini
    •Done. What’s your excuse?
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48. Thank You!
    •Feedback:
    • https://joind.in/talk/view/6243
    • @dshafik
    • davey@engineyard.com
    • Slides:
    • http://daveyshafik.com/slides
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