processes in php

proc.php

<?php
while (count($standby) > 0) {
                if (count($running) < $threads_per_second - 1) {
                    $item = array_shift($standby);
                    if ($item['attempts'] < $item_attempts) {
                        array_unshift($running, $item);
                        $spawned++;
                        echo "Processing " . ++$this->total_count . ": " . $running[0]['code'] . "\n";
                        
                        //spawn off a child
                        $running[0]['attempts']++; //increase the attempts
                        $running[0]['process'] = proc_open('exec nice -n 10 php -f ' . ROOT_DIR . '/trade/process/request_offers.php '
                                . ' "'.$this->email_arg.'" '
                                .' "'.$this->session_id_arg.'" '
                                .' "'. $this->name_arg.'" '
                                .' "'. $this->file_name_arg.'"'
                                . ' "'. $this->admin_arg .'" '
                                . ' "'.$this->current_file.':'.$this->total_files.'" '
                                .' "'.$this->bulk_flag.'" '
                                .' "'.$running[0]['code'].'" '
                                .' "'.$this->marketplace.'" '
                                .DEBUG_LEVEL,
                                $process_description, $running[0]['pipes']);
                    }
                    else {
                        echo "UPC " . $item['code'] . " has utterly failed processing due to unknown reasons.\n";
                    }
                }
                
                // check the status of all children
                for($process = 0; $process < $spawned; $process++) {
                    $status = proc_get_status($running[$process]['process']);
                    //if we are no longer running
                    if (!$status['running']) {
                        //lower the spawn count as a process has died/exited
                        $spawned--;
                        // close the handle to the process and unset it
                        proc_close($running[$process]['process']);
                        unset($running[$process]['process']);
                        //get the status code -- if its not 2 then readd to the standby queue
                        if($status['exitcode'] != 2) {
                            array_push($standby, $running[$process]);
                            echo "UPC " . $running[$process]['code'] . " failed to resolve to an item - requeing item\n";
                        }
                        else {
                            //echo "UPC " . $running[$process]['code'] . " completed successfully after " . $running[$process]['attempts'] . " attempts.\n";
                            $this->update_statement->execute(array('count' => $completed_count++, 'total' => $total, 'id' => $this->session_id_arg));
                        }
                        //regardless, release this usless mess into the world
                        unset($running[$process]);
                    }
                }
                // reindex the array
                $running = array_values($running);
                // wait 1/4 a second before looping
                $wait = (int) (250000);
                usleep($wait);
              }