两个同步AJAX请求将无法并行运行 [英] Two simultaneous AJAX requests won't run in parallel

问题描述

我有问题，两个同时发生的AJAX请求运行。我有一个PHP脚本是将数据导出到XSLX。此操作需要大量的时间，所以我想，以显示进度给用户。我使用AJAX和数据库的方法。其实，我是pretty的确保其用于工作，但我想不出为什么，它不再在任何浏览器中工作。做了一些变化，新的浏览器？

I have problem with two simultaneous AJAX requests running. I have a PHP script which is exporting data to XSLX. This operation take a lot of time, so I'm trying to show progress to the user. I'm using AJAX and database approach. Actually, I'm pretty sure it used to work but I can't figure out why, it's no longer working in any browser. Did something change in new browsers?

$(document).ready(function() {

        $("#progressbar").progressbar();

        $.ajax({
            type: "POST",
            url: "{$BASE_URL}/export/project/ajaxExport",
            data: "type={$type}&progressUid={$progressUid}" // unique ID I'm using to track progress from database
        }).done(function(data) {
            $("#progressbar-box").hide();
            clearInterval(progressInterval);
        });

        progressInterval = setInterval(function() {
            $.ajax({
                type: "POST",
                url: "{$BASE_URL}/ajax/progressShow",
                data: "statusId={$progressUid}" // the same uinque ID
            }).done(function(data) {
                data = jQuery.parseJSON(data);
                $("#progressbar").progressbar({ value: parseInt(data.progress) });
                if (data.title) { $("#progressbar-title").text(data.title); }
            });
        }, 500);

    });

• 进度正确更新数据库
• JS​​的定时器正在试图获得的进展，我可以看到它在控制台中，但所有这些请求都加载一个脚本的整个期间，只要在脚本结束，这些AJAX进度调用加载

  那么，为什么第二AJAX调用等待第一个完成？

  So, why is the second AJAX call waiting for the first one to finish?

  推荐答案

  听起来像是一个会话阻塞问题

  Sounds like a session blocking issue

  在默认情况下PHP写的会话数据到一个文件中。当您启动与在session_start会话（），它会打开文件进行写入，并锁定至prevent并发编辑。这意味着，对每个请求使用会话经历一个PHP脚本必须等待第一次会议上的文件来完成。

  By default PHP writes its session data to a file. When you initiate a session with session_start() it opens the file for writing and locks it to prevent concurrent edits. That means that for each request going through a PHP script using a session has to wait for the first session to be done with the file.

  要解决这个问题的方法是更改​​PHP会话不使用的文件或关闭会话写像这样：

  The way to fix this is to change PHP sessions to not use files or to close your session write like so:

  <?php
      session_start(); // starting the session
  
      $_SESSION['foo'] = 'bar'; // Write data to the session if you want to
  
      session_write_close(); // close the session file and release the lock
  
      echo $_SESSION['foo']; // You can still read from the session.
  

  这篇关于两个同步AJAX请求将无法并行运行的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！