PHP Performance Tuning Timing Program Execution by Statement - Web Development and Design | Tutorial for Java, PHP, HTML, Javascript PHP Performance Tuning Timing Program Execution by Statement - Web Development and Design | Tutorial for Java, PHP, HTML, Javascript

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Sunday, July 7, 2019

PHP Performance Tuning Timing Program Execution by Statement

PHP Performance Tuning


Timing Program Execution by Statement


Problem

You have a block of code and you want to profile it to see how long each statement takes to execute.

Solution

Use the declare construct and the ticks directive:

       function profile($display = false) {
              static $times;
          
              switch ($display) {
              case false:
                     // add the current time to the list of recorded times
                     $times[] = microtime();
                     break;
              case true:
                     // return elapsed times in microseconds
                     $start = array_shift($times);
       
                     $start_mt = explode(' ', $start);
                     $start_total = doubleval($start_mt[0]) + $start_mt[1];
       
                     foreach ($times as $stop) {
                            $stop_mt = explode(' ', $stop);
                            $stop_total = doubleval($stop_mt[0]) + $stop_mt[1];
                            $elapsed[] = $stop_total - $start_total;
                     }

                     unset($times);
                     return $elapsed;
                     break;
              }
       }

       // register tick handler
       register_tick_function('profile');
       
       // clock the start time
       profile();

       // execute code, recording time for every statement execution
       declare (ticks = 1) {
              foreach ($_SERVER['argv'] as $arg) {
                     print "$arg: " . strlen($arg) ."\n";
              }
       }

       // print out elapsed times
       print "---\n";
       $i = 0;
       foreach (profile(true) as $time) {
              $i++;
              print "Line $i: $time\n";
       }

Discussion

The ticks directive allows you to execute a function on a repeatable basis for a block of code. The number assigned to ticks is how many statements go by before the functions that are registered using register_tick_function() are executed.

In the Solution, we register a single function and have the profile() function execute for every statement inside the declare block. If there are two elements in $_SERVER['argv'], profile() is executed six times: once when the clocks starts; twice for the two times through the foreach loop; another two when the print strlen($arg) line is executed; and finally, once when foreach returns false:

       Line 1: 5.3882598876953E-5
       Line 2: 5.6982040405273E-5
       Line 3: 6.2942504882812E-5
       Line 4: 6.5803527832031E-5
       Line 5: 6.7949295043945E-5
       Line 6: 6.9856643676758E-5

You can also set things up to call two functions every three statements:

       register_tick_function('profile');
       register_tick_function('backup');

       declare (ticks = 3) {
              // code...
       }

You can also pass additional parameters into the registered functions, which can be object methods instead of regular functions:

       // pass "parameter" into profile()
       register_tick_function('profile', 'parameter');

       // call $car->drive();
       $car = new Vehicle;
       register_tick_function(array($car, 'drive'));

If you want to execute an object method, pass the object and the name of the method encapsulated within an array. This lets the register_tick_function() know you’re referring to an object instead of a function.

Call unregister_tick_function() to remove a function from the list of tick functions:

       unregister_tick_function('profile');

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