php - Results of a simple execution time check contradict Xdebug profiling results -

i have expensive method removecolumns(...), in addition gets called multiple times. want increase performance. analyze optimization results use 2 tools: (1) xdebug profiler webgrind , (2) simple execution time measuring script (that executed on command line within phpunit test method):

$timestart = microtime(true); ($i=0 ; $i < 1000000; $i++) {     // code measure     $this->...->removecolumns($testarray, $columnnames, $iswhitelist); } $timestop = microtime(true); $resulttime = $timestop - $timestart; $cycletime = $resulttime / $i; echo number_format($cycletime, 10, ',', '') . ' sec/run'; die(php_eol . '###' . php_eol); 

but i'm looking @ results -- , see, results ot both tooas absolutely contrarian each other.

the execution time measuring script's results are:

variant     sec/run (x69)       sec/run (x1000)     sec/run (x10000)    sec/run (x100000) 1           0,0000121144        0,0000102139        0,0000092316        0,0000089004 2           0,0000115650        0,0000112779        0,0000098540        0,0000098941 3           0,0000228260        0,0000240171        0,0000250236        0,0000800230  difference ms (1-2)     0,0000005494    -0,0000010640   -0,0000006224   -0,0000009937 yield % (1-2)           4,54%           -10,42%         -6,74%          -11,16% difference ms (1-3)     -0,0000107116   -0,0000138032   -0,0000157920   -0,0000711226 yield % (1-3)           -88,42%         -135,14%        -171,06%        -799,09% 

as can see, optimization failed. when method called not often, performance becomes better, more calls, worse (nonlinear, 900% performance losses on 100.000 calls).

now let's see xdebug profiler's results:

variant xdp-filename    xdp-filesize    calls   total self (ms) total inclusive (ms) 1       1474536556      445,678 kb      69      77325           77403 2       1474537523      402,208 kb      69      1267            1270 3       1474539908      402,963 kb      69      2443            2455  difference ms (1-2)                             76058           76133 yield % (1-2)                                   98,36%          98,36% difference ms (1-3)                             74882           74948 yield % (1-3)                                   96,84%          96,83% 

so here performance of improved variants (2 , 3) is/seems better, performance of variant 1.

what wrong here , how fix adequate performance testing results?

---

all 3 variants of method, i'm optimizing:

variant 1

public function removecolumns(array $table, array $columnnames, bool $iswhitelist = false) {     foreach ($table $rowkey => $row) {         if (is_array($row)) {             foreach ($row $fieldname => $fieldvalue) {                 $remove = $iswhitelist                     ? ! in_array($fieldname, $columnnames)                     : in_array($fieldname, $columnnames)                 ;                 if ($remove) {                     unset($table[$rowkey][$fieldname]);                 }             }         }     }     return $table; } 

variant 2

public function removecolumns(array $table, array $columnnames, bool $iswhitelist = false) {     $tablekeys = array_keys($table);     $firstrowkey = $tablekeys[0];     $firstrow = $table[$firstrowkey];     $allcolumnnames = array_keys($firstrow);     $resultcolumns = [];     foreach ($allcolumnnames $columnname) {         $remain = $iswhitelist             ? in_array($columnname, $columnnames)             : ! in_array($columnname, $columnnames)         ;         if($remain) {             $resultcolumns[$columnname] = array_column($table, $columnname);         }     }     $index = 0;     $resulttable = [];     foreach ($resultcolumns $resultcolumnname => $resultcolumn) {         foreach ($tablekeys $index => $tablekey) {             $resulttable[$tablekey][$resultcolumnname] = $resultcolumn[$index];         }     }     return $resulttable; } 

variant 3

public function removecolumns(array $table, array $columnnames, bool $iswhitelist = false) {     $tablekeys = array_keys($table);     $firstrowkey = $tablekeys[0];     $firstrow = $table[$firstrowkey];     $allcolumnnames = array_keys($firstrow);     $columns = [];     $i = 0;     $arraymapinputvarnames = [];     foreach ($allcolumnnames $columnname) {         $remain =             ($iswhitelist && in_array($columnname, $columnnames)) ||             (! $iswhitelist && ! in_array($columnname, $columnnames))         ;         if($remain) {             $varname = 'column' . $i++;             $$varname = $columns[$columnname] = array_column($table, $columnname);             $arraymapinputvarnames[] = '$' . $varname;         }     }     $arraymapinputstring = implode(', ', $arraymapinputvarnames);     eval('$rows = array_map(null, ' . $arraymapinputstring . ');');     foreach ($rows $index => $row) {         $rows[$index] = array_combine(array_keys($columns), array_values($row));     }     $table = array_combine(array_keys($table), $rows);     return $table; } 

is function intended do?

<?php $table=array(     'col1'=>'val1',     'col2'=>'val2',     'col3'=>'val3',     'col4'=>'val4' );  $columnnames=array(     'col2','col3' );  function removecolumns($table, $columnnames, $iswhitelist = false) {     if ($iswhitelist) return array_intersect_key($table,array_flip($columnnames));     return array_diff_key($table,array_flip($columnnames)); }  print 'blacklist:'.var_export(removecolumns($table,$columnnames,false),1).php_eol; print 'whitelist:'.var_export(removecolumns($table,$columnnames,true),1).php_eol; 

output:

blacklist:array (     'col1' => 'val1',     'col4' => 'val4', ) whitelist:array (     'col2' => 'val2',     'col3' => 'val3', ) 

but did not measured performance. upload xdebug output of code somewhere?