id	summary	reporter	owner	description	type	status	priority	milestone	component	version	severity	resolution	keywords	cc
18738	Improving cron spawning and other non-blocking HTTP requests	johnbillion	dd32	"The order of preference for transport methods in the HTTP API is cURL, streams, fsockopen. However cURL and streams cannot perform non-blocking requests, but fsockopen can. Therefore, fsockopen should be the highest priority transport method for non-blocking HTTP requests.

Here's an example. I have a script at `http://ctftw.com/sleep.php` which sleeps for 5 seconds.
{{{
$start = microtime( true );
wp_remote_get( 'http://ctftw.com/sleep.php', array(
	'blocking' => false
) );
$end = microtime( true );
var_dump( $end - $start );
}}}
When the cURL or streams transports are used, this request blocks the page for 5 seconds (the default request timeout is 5 seconds).

Let's disable the cURL and streams transports (leaving only fsockopen) and try again:
{{{
add_filter( 'use_curl_transport',    '__return_false' );
add_filter( 'use_streams_transport', '__return_false' );

$start = microtime( true );
wp_remote_get( 'http://ctftw.com/sleep.php', array(
	'blocking' => false
) );
$end = microtime( true );
var_dump( $end - $start );
}}}
This request does not block the page because fsockopen returns immediately after sending the request.

== Cron Spawning ==

This is a benefit to core because it improves the cron spawner (and can potentially fix #8923). The cron spawner uses a timeout of 0.01 seconds and a non-blocking request, but actually takes longer than 0.01 seconds.

Example:
{{{
$cron_url = get_option( 'siteurl' ) . '/wp-cron.php?doing_wp_cron';
$start = microtime( true );
wp_remote_post( $cron_url, array(
	'timeout' => 0.01,
	'blocking' => false
) );
$end = microtime( true );
var_dump( $end - $start );
}}}
This request takes around 1.1 seconds on the three servers I've tested it on.

Let's disable cURL and streams again (leaving only fsockopen) and see what we get:
{{{
add_filter( 'use_curl_transport',    '__return_false' );
add_filter( 'use_streams_transport', '__return_false' );

$cron_url = get_option( 'siteurl' ) . '/wp-cron.php?doing_wp_cron';
$start = microtime( true );
wp_remote_post( $cron_url, array(
	'timeout' => 0.01,
	'blocking' => false
) );
$end = microtime( true );
var_dump( $end - $start );
}}}
On each of my three servers I see a time of around 0.001 seconds.

We can therefore improve the cron spawner by setting fsockopen as the preferred transport method for non-blocking HTTP requests.

In an attempt to address #8923, we can change the cron request timeout to 1 second. If fsockopen is used, the request is lightning fast at ~0.001 seconds. If it's not available and the HTTP API falls back to cURL or streams then it takes ~1.1 second, which is the same time it takes currently. (Hopefully that makes sense.)

Patch coming up for those who want to test it."	enhancement	accepted	high	Future Release	HTTP		normal		has-patch 3.6-early	kpayne@… mestovar