我有一个PHP脚本可能需要几分钟才能完成。该脚本将文件下载到用户PC。
我有另一个PHP脚本，它的作用是监视主下载脚本的进度。该脚本由客户端通过AJAX调用调用，并应返回下载进度信息。
现在，我的测试显示，在执行主脚本期间（换句话说，在文件下载期间），AJAX - monitor脚本根本不返回任何值。当主 - 下载脚本完成时，它开始正常运行。
PHP是否可能无法同时运行两个或更多脚本，并且只允许按顺序运行脚本？
我可以插入我的代码，但我认为出于我的问题的目的，它不是必需的。我只需要知道，如果两个或多个PHP脚本可以同时为同一个客户端运行。
我用：
当我被要求向您展示我的代码时，请参阅以下代码部分。
主要PHP（稍后下载）脚本：
<?php
// disable script expiry
set_time_limit(0);
// start session if session is not already started
if (session_status() !== PHP_SESSION_ACTIVE)
{
session_start();
}
// prepare session variable
$_SESSION['DownloadProgress'] = 0;
for( $count = 0; $count < 60; $count++)
{
sleep(1);
echo "Iteration No: " . $count;
$_SESSION['DownloadProgress']++;
echo '$_SESSION[\'DownloadProgress\'] = ' . $_SESSION['DownloadProgress'];
flush();
ob_flush();
}
?>
监控PHP脚本：
// construct JSON
$array = array("result" => 1, "download_progress" => $_SESSION['DownloadProgress']);
echo json_encode($array);
?>
JavaScript代码，我调用这两个PHP脚本：
SearchResults.myDownloadFunction = function()
{
console.log( "Calling: PHP/fileDownload.php" );
window.location.href = 'PHP/fileDownload.php?upload_id=1';
console.log( "Calling: getUploadStatus()" );
FileResort.SearchResults.getUploadStatus();
console.log( "Called both functions" );
};
JavaScript AJAX：
// call AJAX function to get upload status from the server
SearchResults.getUploadStatus = function ()
{
var SearchResultsXMLHttpRequest = FileResort.Utils.createRequest();
if (SearchResultsXMLHttpRequest == null)
{
console.log("unable to create request object.");
}
else
{
SearchResultsXMLHttpRequest.onreadystatechange = function ()
{
console.log("Response Text: " + SearchResultsXMLHttpRequest.responseText);
console.log("AJAX Call Returned");
if ((SearchResultsXMLHttpRequest.readyState == 4) && (SearchResultsXMLHttpRequest.status == 200))
{
//if (that.responseJSON.result == "true")
{
var responseJSON = eval('(' + SearchResultsXMLHttpRequest.responseText + ')');
console.log("Download Progress: " + responseJSON.download_progress);
}
}
}
var url = "PHP/fileDownloadStatus.php";
SearchResultsXMLHttpRequest.open("POST", url, true);
SearchResultsXMLHttpRequest.send();
}
};
稍后将下载文件的PHP脚本：
<?php
// disable script expiry
set_time_limit(0);
for( $count = 0; $count < 60; $count++)
{
sleep(1);
}
?>
输出测试值的PHP监控脚本：
<?php
$test_value = 25;
// construct JSON
$array = array("result" => 1, "download_progress" => $test_value);
//session_write_close();
echo json_encode($array);
?>
以下都会调用这两个脚本：
SearchResults.myDownloadFunction = function()
{
console.log( "Calling: PHP/fileDownload.php" );
window.setTimeout(FileResort.SearchResults.fileDownload(), 3000);
console.log( "Calling: getUploadStatus()" );
window.setInterval(function(){FileResort.SearchResults.getDownloadStatus()}, 1000);
console.log( "Called both functions" );
};
答案 0 :(得分：5)
如果没有更多信息，这里有一些可能性，但我怀疑问题是你的会话。当使用会话文件的脚本启动时，PHP将锁定会话文件，直到调用session_write_close()或脚本完成。会话被锁定时，访问session的任何其他文件将无法执行任何操作，直到第一个脚本完成并写入/关闭会话文件（因此ajax调用必须等到会话文件被释放） 。尝试在第一个脚本上完成验证等后立即编写会话，后续脚本应该能够启动。
这是一种快速而肮脏的方法：
这是用户要点击下载链接的页面
<html>
<head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script>
$(document).ready(function(e) {
//Every 500ms check monitoring script to see what the progress is
$('#large_file_link').click(function(){
window.p_progress_checker = setInterval( function(){
$.get( "monitor.php", function( data ) {
$( ".download_status" ).html( data +'% complete' );
//we it's done or aborted we stop the interval
if (parseInt(data) >= 100 || data=='ABORTED'){
clearInterval(window.p_progress_checker);
}
//if it's aborted we display that
if (data=='ABORTED'){
$( ".download_status" ).html( data );
$( ".download_status" ).css('color','red').css('font-weight','bold');
}
})
}, 500);
});
});
</script>
</head>
<body>
<div class="download_status"><!-- GETS POPULATED BY AJAX CALL --></div>
<p><a href="download.php" id="large_file_link">Start downloading large file</a></p>
</body>
</html>
这是为大文件提供服务的PHP脚本...它将其分成块，并在发送每个块后关闭会话，以便会话可供其他脚本使用。另请注意，我添加了ignore_user_abort / connection_aborted处理程序，以便在终止连接时可以采取特殊操作。 这是实际处理session_write_close()问题的部分，因此请关注此脚本。
<?php
/*Ignore user abort so we can catch it with connection_aborted*/
ignore_user_abort(true);
function send_file_to_user($filename) {
//Set the appropriate headers:
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.basename($filename));
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate');
header('Pragma: public');
header('Content-Length: ' . filesize($filename));
$chunksize = 10*(1024); // how many bytes per chunk (i.e. 10K per chunk)
$buffer = '';
$already_transferred =0;
$file_size = filesize( $filename );
$handle = fopen($filename, 'rb');
if ($handle === false) {
return false;
}
while (!feof($handle)) {
/*if we're using a session variable to commnicate just open the session
when sending a chunk and then close the session again so that other
scripts which have request the session are able to access it*/
session_start();
//see if the user has aborted the connection, if so, set the status
if (connection_aborted()) {
$_SESSION['file_progress'] = "ABORTED";
return;
}
//otherwise send the next packet...
$buffer = fread($handle, $chunksize);
echo $buffer;
ob_flush();
flush();
//now update the session variable with our progress
$already_transferred += strlen($buffer);
$percent_complete = round( ($already_transferred / $file_size) * 100);
$_SESSION['file_progress'] = $percent_complete;
/*now close the session again so any scripts which need the session
can use it before the next chunk is sent*/
session_write_close();
}
$status = fclose($handle);
return $status;
}
send_file_to_user( 'large_example_file.pdf');
?>
这是一个通过Ajax调用的脚本，负责将进度报告回目标网页。
<?
session_start();
echo $_SESSION['file_progress'];
?>