multithreading - php exec() haphazardly working in pthreads -

i use loop exec() file 300 times in pthreads. full 300 exec() calls successful, times few of exec() fail , between 295 or 299 successful executes of file.

the error code exec() comes @ #127, checked file_exists on failures , says "file exists", says "file not executable" on failures. strange because executable other 295 times within loop.

my pthread version 2 months old. confident don't have pthread workers sharing files or writing same spots. scratching head else can do.

class workerthreads extends thread {     private $workerid;      public function __construct($id)     {         $this->workerid = $id;     }      public function run()     {  $mainfile="/pastlotto_1/".$this->workerid."/preset_pthread.php";          for($x=0; $x<100; $x++) {      for($o=0; $o<3; $o++)     {         $command="php $mainfile";         $finde=exec($command,$output,$return_var);          if($return_var !== 0){       echo " file not executed @ worker id ".$this->workerid."\n";     echo $return_var."\n";      if (file_exists($mainfile)) {     echo "the file $mainfile exists\n"; } else {     echo "the file $mainfile not exist\n"; }   if(is_executable($mainfile))   {   echo ("file executable\n");   } else   {   echo ("file not executable\n");   }  } else{     echo "file executed successfully"; }     } }         }//end of run  }  for($r=0; $r<1; $r++) { $workers = [];  // initialize , start threads foreach (range(0,2) $j) {      $workers[$j] = new workerthreads($j);     $workers[$j]->start();       //echo $i." worker started\n"; }  // let threads come foreach (range(0,2) $j) {     $workers[$j]->join();  } unset($workers);  } 

i able solve problem changing code fires pthreads from:

for($r=0; $r<1; $r++) { $workers = [];  // initialize , start threads foreach (range(0,2) $j) {      $workers[$j] = new workerthreads($j);     $workers[$j]->start();       //echo $i." worker started\n"; }  // let threads come foreach (range(0,2) $j) {     $workers[$j]->join();  } unset($workers);  } 

to replacement code:

$p = new pool(3);    // initialize , start threads  for($b=0; $b<3; $b++) {         $tasks[$b]= new workerthreads($b);       }     // add tasks pool queue     foreach ($tasks $task) {         $p->submit($task);     }      // shutdown wait current queue completed     $p->shutdown();