kelatebaru

Oftentimes, better runtime can result in higher memory usage. Here is an example to create some strings to test bulk inserts on Redis: $cmd = ""; $start = microtime(true); for ($i=0; $i<1000000; $i+=2) $cmd .= "SET entity:".$i.":key value_".($i+1)."\r\n"; echo number_format(microtime(true)-$start, 1)."s\n"; // 0.7s echo number_format(memory_get_usage(true)/1048576, 1)." MB\n"; // 17.5 MB echo number_format(memory_get_peak_usage(true)/1048576, 1)." MB\n"; // 17.5 MB $cmd = ""; $start = microtime(true); $cmd = vsprintf(str_repeat("SET entity:%d:key value_%d\r\n", 500000), range(0,1000000)); echo number_format(microtime(true)-$start, 1)."s\n"; // 0.4s echo number_format(memory_get_usage(true)/1048576, 1)." MB\n"; // 30.8 MB echo number_format(memory_get_peak_usage(true)/1048576, 1)." MB\n"; // 128.5 MB (PHP 5.4.5, 2.5 GHz, win64) We see that the same result can be c...

To handle a lot of traffic, we need a fast controller with very little memory overhead. First, we implement a dynamic controller . The design is based on the micro frameworks Slim and Silex . The first example maps the URL "http://server/index.php/blog/2012/03/02" to a function with the parameters $year, $month and $day: // index.php, handle /blog/2012/03/02 $app = new App(); $app->get('/blog/:year/:month/:day', function($year, $month, $day) { printf('%d-%02d-%02d', $year, $month, $day); }); Our controller is a class named App and uses the get() function to map a GET request. Parameters mapped to the function are marked with a colon. Optional parameters are written inside brackets. Here is an example: // handle /blog, /blog/2012, /blog/2012/03 and /blog/2012/03/02 $app = new App(); $app->get('/blog(/:year(/:month(/:day)))', function($year=2012, $month=1, $day=1) { printf('%d-%02d-%02d', $year, $month, $day); }); Instead of ...

i18n is always difficult to implement and costs a lot performance. Normally, implementations use gettext() or a custom t()-function to translate a string. t() searches a INI or XML file for a translation key and returns the value. For example t('setting', 'de'), gives the German translation 'Einstellung'. Typical optimizations use associative arrays (hashmaps) loaded into APC or Memcached. This requires a lot of memory for the array and produces a lot of cpu cycles for calling t() all the time. So the question is, can we do this better? Yes! We use a just-in-time compiler for our PHP files and write the compiled PHP files to disk, so APC can cache them like regular PHP files. An example PHP class looks like this: // example.php <?php class example { public function now() { return '{t}Hello World, now it is:{/t} '.date('{t}m/d/Y g:i a{/t}'); } } The "{t}" and "{/t}" patterns serve as opening and closing tags indi...

Here is a list of things you should not do in PHP. Most of the stuff is pretty obvious, but over the years I've seen a lot of them. In most cases, these problems remain hidden until data grows above 10000 entries. So on a development system, things are always fast and there are no problems with memory limits :-) Suppose we have a table with 100k entries: $db->query('create table stats (c1 int(11) primary key, c2 varchar(255))'); $db->query('begin'); for ($i=0; $i<100000; $i++) { $db->query('insert into stats values ('.$i.','.($i*2).')'); } $db->query('commit'); Populate a big array instead of streaming results: $result = $db->query('select * from stats'); $array = $result->fetch_all(); // 35M // or while ($row = $result->fetch_assoc()) $array[] = $row; // 35M // or while ($row = $result->fetch_array()) $array[] = $row; // 44.5M // process $array ... // instead of: while ($row = $result->fetch...

Lessons learned: objects need more memory than arrays (+ 2-10 percent) comparing 32bit to 64bit systems, memory consumption increases by 100-230 percent if array values are numeric, don't save them as strings! saving 1M integers takes 200M of memory with PHP on a 64bit plattform (increase by factor 25) using SplFixedArray can reduce memory usage by 20-130 percent avoid big Arrays and Objects in PHP whenever possible (don't use file('big_file') or explode("\n", file_get_contents('big_file')), etc.) use streams whenever possible (fopen, fsockopen, etc.) use generators when available with PHP 5.5 ( RFC ) If you need to save memory temporarily in your script, you can stringify your array (increasing cpu usage and runtime): $a = array(); for ($i=0; $i $a[] = $i; } $a = implode(',', $a); // or $a = json_encode($a); echo number_format(memory_get_usage(true)/1048576, 2)."\n"; // 8.0 M (64bit), 7.5 M (32bit) Here is a small script to sh...