close a connection early

Question

I'm attempting to do an AJAX call (via JQuery) that will initiate a fairly long process. I'd like the script to simply send a response indicating that the process has started, but JQuery won't return the response until the PHP script is done running.

I've tried this with a "close" header (below), and also with output buffering; neither seems to work. Any guesses? or is this something I need to do in JQuery?

<?php

echo( "We'll email you as soon as this is done." );

header( "Connection: Close" );

// do some stuff that will take a while

mail( '[e-mail]', "okay I'm done", 'Yup, all done.' );

?>

Answer 1

You can use Fast-CGI with PHP-FPM to use the fastcgi_end_request() function. In this way, you can continue to do some processing while the response has already been sent to the client.

• example of how to use fastcgi_finish_request() (Nov 2010)

You find this in the PHP manual here: FastCGI Process Manager (FPM); But that function specifically is not further documented in the manual. Here the excerpt from the PHP-FPM: PHP FastCGI Process Manager Wiki:

---

fastcgi_finish_request()

Scope: php function Category: Optimization

This feature allows you to speed up implementation of some php queries. Acceleration is possible when there are actions in the process of script execution that do not affect server response. For example, saving the session in memcached can occur after the page has been formed and passed to a web server. fastcgi_finish_request() is a php feature, that stops the response output. Web server immediately starts to transfer response "slowly and sadly" to the client, and php at the same time can do a lot of useful things in the context of a query, such as saving the session, converting the downloaded video, handling all kinds of statistics, etc.

fastcgi_finish_request() can invoke executing shutdown function.

Answer 2

You could try to do multithreading.

you could whip up a script that makes a system call ( using shell_exec ) that calls the php binary with the script to do your work as the parameter. But I don't think that is the most secure way. Maybe you can thighten stuff up by chrooting the php process and other stuff

Alternatively, there's a class at phpclasses that do that http://www.phpclasses.org/browse/package/3953.html. But I don't know the specifics of the implementation

Answer 3

After trying many different solutions from this thread (after none of them worked for me), I've found solution on official PHP.net page:

function sendResponse($response) {
    ob_end_clean();
    header("Connection: close\r\n");
    header("Content-Encoding: none\r\n");
    ignore_user_abort(true);
    ob_start();

    echo $response; // Actual response that will be sent to the user

    $size = ob_get_length();
    header("Content-Length: $size");
    ob_end_flush();
    flush();
    if (ob_get_contents()) {
        ob_end_clean();
    }
}

Answer 4

It's necessary to send these 2 headers:

Connection: close
Content-Length: n (n = size of output in bytes )

Since you need know the size of your output, you'll need to buffer your output, then flush it to the browser:

// buffer all upcoming output
ob_start();
echo "We'll email you as soon as this is done.";

// get the size of the output
$size = ob_get_length();

// send headers to tell the browser to close the connection
header("Content-Length: $size");
header('Connection: close');

// flush all output
ob_end_flush();
ob_flush();
flush();

// if you're using sessions, this prevents subsequent requests
// from hanging while the background process executes
if (session_id()) session_write_close();

/******** background process starts here ********/

Also, if your web server is using automatic gzip compression on the output (ie. Apache with mod_deflate), this won't work because actual size of the output is changed, and the Content-Length is no longer accurate. Disable gzip compression the particular script.

For more details, visit http://www.zulius.com/how-to/close-browser-connection-continue-execution

Answer 5

Here's a modification to Timbo's code that works with gzip compression.

// buffer all upcoming output
if(!ob_start("ob_gzhandler")){
    define('NO_GZ_BUFFER', true);
    ob_start();
}
echo "We'll email you as soon as this is done.";

//Flush here before getting content length if ob_gzhandler was used.
if(!defined('NO_GZ_BUFFER')){
    ob_end_flush();
}

// get the size of the output
$size = ob_get_length();

// send headers to tell the browser to close the connection
header("Content-Length: $size");
header('Connection: close');

// flush all output
ob_end_flush();
ob_flush();
flush();

// if you're using sessions, this prevents subsequent requests
// from hanging while the background process executes
if (session_id()) session_write_close();

/******** background process starts here ********/

Answer 6

If flush() function does not work. You must set next options in php.ini like:

output_buffering = Off  
zlib.output_compression = Off