pfsockopen is useful for having scripts executing others in the background.
I'm writing an intra-site search engine with spidering capabilities. To spider a ~200 page site and index all the text takes about 60 seconds. Because I don't want the user waiting 60s for the script to finish and thinking it's timing out, I use pfsockopen to have the server open an HTTP connection with itself to execute the script in the background. Once the spidering is done, the connection is closed without capturing the HTTP response. The output isn't important, the spidering is!
I just make the script execute the following:
<?php
$st = pfsockopen($_SERVER['HTTP_HOST'], 80, $erstr, $errno, 5);
fwrite($st, "GET {$_SERVER['PHP_SELF']}?$key HTTP/1.0\r\nHost: {$_SERVER['HTTP_HOST']}\r\n\r\n");
?>
Where $key is the QUERY_STRING trigger which starts the spidering process. This script is executed in the background while the main script is free to finish loading and display a message like: "The database is being reindexed, please wait."
BTW, I set a flag in another MySQL table which prevents searches while the spider is crawling.
pfsockopen
(PHP 3 >= 3.0.7, PHP 4, PHP 5)
pfsockopen -- Open persistent Internet or Unix domain socket connectionDescription
resource pfsockopen ( string hostname [, int port [, int &errno [, string &errstr [, float timeout]]]] )This function behaves exactly as fsockopen() with the difference that the connection is not closed after the script finishes. It is the persistent version of fsockopen().
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User Contributed Notes
grey at greywyvern dot moc
07-Aug-2004 12:06
07-Aug-2004 12:06
pulstar at ig dot com dot br
24-Sep-2003 07:15
24-Sep-2003 07:15
Persistent connections either in socket or databases should be used only in servers where the limits are well defined. For example, the number of allowed connections in a database must be greater than the number of Apache's processes, or the connections will be refused by the database (this will surely occur if you use persistent connections). The same may occur with socket connections. This is up to the service configuration. In my opinion, persistent connections are useful only if you have total control over the one or more servers involved, like on a heavy loaded dedicated server for example, where the little gain in performance worth the use of such connections. Never use them in a shared server.
dietrich at ganx4 dot com
09-May-2003 05:08
09-May-2003 05:08
Re: persisting connections across script executions
SAPI modules allow this (i've only tried w/ ISAPI, but others might also allow).
also, Shane Caraveo's FastCGI allows this.
php dot net at domainofdarkness dot com
30-Jan-2001 07:26
30-Jan-2001 07:26
OK, WRT to the p* functions opening a new connection when one already exists. It is my understanting that (under Apache anyways) this is on a per-process basis. If you do a 'ps auxw|grep httpd' on your server you will see more than one process. What p* does is make a p-connection on one of those processes only, the one that actually handles your request. Chances are that when you hit the page again it will be answered by a different process. I'm guessing if you keep hitting reload you'll get around to the original process again and there will be no error message or second connection open. Anyhow, this is true of all p* functions; they open not one connection per server, but one connection per server _process_.