Related content about php session read-write lock
php session read-write lock
Let’s look at an example first, function:
1. Click a button on the page, ajax executes php, and session is used in php to record the execution step.
2. Use ajax to poll another php, obtain the data in the session, and output the execution step.
session.html Call php to execute and output the execution steps
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html;charset=utf-8">
<script src="//code.jquery.com/jquery-1.11.0.min.js"></script>
<title> session lock </title>
</head>
<body>
<input type="button" value="handle" onclick="handle()">
<p id="result"></p>
<script type="text/javascript">
function handle(){
$.get("handle.php"); // 执行handle
// 每500毫秒请求,获取执行到第几步
var et = setInterval(function(){
$.get("getstep.php",
function(data){
$('#result').html('当前执行:' + data + '<br>');
if(data=='complete'){
clearInterval(et);
}
}
);
},500);
}
</script>
</body>
</html>
handle.php Execute and record the execution step
<?php
session_start();
$_SESSION['step'] = '';
$n = 1;
while($n<=10){
$_SESSION['step'] = $n;
sleep(1);
$n++;
}
$_SESSION['step'] = 'complete';
?>
##getstep.php Get the execution step
<?php session_start(); echo isset($_SESSION['step'])? $_SESSION['step'] : ''; ?>
When executed, it was found that instead of returning at every step, complete was returned directly after waiting for 10 seconds.
After executing session_start(), the session will be locked. Until the page execution is completed.
Therefore, during the execution of the page, writing to the session will only be saved in the memory and will not be written to the session file.
#To read the session, you need to wait until the session lock is unlocked before it can be read.
We can use session_write_close() to write data to the session file and end the session process. In this way, there is no need to wait for the page execution to complete, and you can also get the execution step.
But there is a problem with this, that is, after executing session_write_close(), any write operation to the session will not work. Because the session process has ended.
Therefore, when you need to write a session again, add session_start() in front
session_start — Start new or resume existing session
##session_write_close — Write session data and end session
handle.php Click the following modifications to get the execution step Related recommendations: The above is the detailed content of Related content about php session read-write lock. For more information, please follow other related articles on the PHP Chinese website!<?php
session_start();
$_SESSION['step'] = '';
$n = 1;
while($n<=10){
$_SESSION['step'] = $n;
session_write_close(); // 将数据写入session文件,并结束session进程
session_start(); // 重新创建session进程
sleep(1);
$n++;
}
$_SESSION['step'] = 'complete';
?>This article explains the content about php session read-write lock. For more related information, please Follow php Chinese website.
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
What are public, private, and protected in php
Aug 24, 2025 am 03:29 AM
Public members can be accessed at will; 2. Private members can only be accessed within the class; 3. Protected members can be accessed in classes and subclasses; 4. Rational use can improve code security and maintainability.
How to execute an UPDATE query in php
Aug 24, 2025 am 05:04 AM
Using MySQLi object-oriented method: establish a connection, preprocess UPDATE statements, bind parameters, execute and check the results, and finally close the resource. 2. Using MySQLi procedure method: connect to the database through functions, prepare statements, bind parameters, perform updates, and close the connection after processing errors. 3. Use PDO: Connect to the database through PDO, set exception mode, pre-process SQL, bind parameters, perform updates, use try-catch to handle exceptions, and finally release resources. Always use preprocessing statements to prevent SQL injection, verify user input, and close connections in time.
How to use cURL in php
Aug 24, 2025 am 08:32 AM
cURLinPHPenablessendingHTTPrequests,fetchingAPIdata,anduploadingfiles.Initializewithcurl_init(),setoptionslikeCURLOPT_URLandCURLOPT_RETURNTRANSFER,useCURLOPT_POSTforPOSTrequests,sendJSONwithproperheaders,handleerrorsviacurl_errno()andHTTPcodeswithcur
How to read a CSV file in PHP?
Aug 29, 2025 am 08:06 AM
ToreadaCSVfileinPHP,usefopen()toopenthefile,fgetcsv()inalooptoreadeachrowasanarray,andfclose()tocloseit;handleheaderswithaseparatefgetcsv()callandspecifydelimitersasneeded,ensuringproperfilepathsandUTF-8encodingforspecialcharacters.
How to use AJAX with php
Aug 29, 2025 am 08:58 AM
AJAXwithPHPenablesdynamicwebappsbysendingasynchronousrequestswithoutpagereloads.1.CreateHTMLwithJavaScriptusingfetch()tosenddata.2.BuildaPHPscripttoprocessPOSTdataandreturnresponses.3.UseJSONforcomplexdatahandling.4.Alwayssanitizeinputsanddebugviabro
What is the difference between isset and empty in php
Aug 27, 2025 am 08:38 AM
isset()checksifavariableexistsandisnotnull,returningtrueevenforzero,false,oremptystringvalues;2.empty()checksifavariableisnull,false,0,"0","",orundefined,returningtrueforthese"falsy"values;3.isset()returnsfalsefornon-exi
Edit bookmarks in chrome
Aug 27, 2025 am 12:03 AM
Chrome bookmark editing is simple and practical. Users can enter the bookmark manager through the shortcut keys Ctrl Shift O (Windows) or Cmd Shift O (Mac), or enter through the browser menu; 1. When editing a single bookmark, right-click to select "Edit", modify the title or URL and click "Finish" to save; 2. When organizing bookmarks in batches, you can hold Ctrl (or Cmd) to multiple-choice bookmarks in the bookmark manager, right-click to select "Move to" or "Copy to" the target folder; 3. When exporting and importing bookmarks, click the "Solve" button to select "Export Bookmark" to save as HTML file, and then restore it through the "Import Bookmark" function if necessary.
How to configure SMTP for sending mail in php
Aug 27, 2025 am 08:08 AM
Answer: Using the PHPMailer library to configure the SMTP server can enable sending mails through SMTP in PHP applications. PHPMailer needs to be installed, set up SMTP host, port, encryption method and authentication credentials of Gmail, write code to set sender, recipient, topic and content, enable 2FA and use application password to ensure that the server allows SMTP connection, and finally call the send method to send email.
