The Arcive of Official vBulletin Modifications Site.

About Developer · **Released**: 10-17-2007

How vB's Cron Jobs Work (and the problem with them)
vBulletin has a great, built-in scheduled task system. It relies on an invisible pixel image output on the bottom of the forum pages to run the scheduled tasks (cron jobs). It works like this: When a user visits a page, vB checks to see if there are any pending cron jobs to execute. If there are, the cron image is inserted at the bottom of the page. That image, instead of displaying a real image, actually calls the scheduled task script which first returns the image, then proceeds to execute the scheduled task. This setup can cause the page load to hang, depending on what browser you're using. vB goes to great lengths to send the content-length header, then flush the image data to the browser. This causes some browsers to stop loading the page even though the script isn't finished running (it has to execute the cron job), since the data returned matches the content-length header. However, not all browsers are that smart. Sometimes they sit there with whatever indicator they have spinning, saying the page is still loading, until the scheduled task has finished.

How this product works, and how it fixes the problem
This add-on fixes the problem. How it works:
1. First it checks to see if the user has Javascript enabled. No Javascript means the standard vB cron image is used, so your scheduled tasks keep running.
2. If Javascript is enabled, then a short snippet of Javascript is inserted at the bottom of the page instead of the cron image.
3. What this Javascript does is first wait until the page is completely loaded. After the page is loaded, it ask for the standard vB cron image, which runs your scheduled task. After the image is loaded, it displays it (it's invisible) at the bottom of the page. It's as simple as that.

The advantage of this setup is that the cron image is requested via Javascript after the page is done loading, so that the user doesn't think something is wrong and wonder why the page won't finish loading.

Installation
Import the product XML via the Product Manager. You can enable/disable the product in the JS Cron Image Options group.

Technical Specs
This product adds one plugin which inserts Javascript where the vB cron image used to go. That's it.

History
Version 1.0.0 - Initial Release
Version 1.0.1 - Better compatibility with vBa and other 'portal' scripts. $vbulletin->options['bburl'] is prepended to the cron image URL.

This product doesn't change how cron jobs execute at all, it only requests the cron image (which starts cron job execution) in a different way, so that the user doesn't have forever-loading pages.

If you use this, please click Mark As Installed.

Milad · #12 10-18-2007, 08:13 PM

Very good.

But, will be there a conflict with the <body onload="bla bla bla">?

Is it compatible with all browsers? especially IE6-7 FF1.5 FF2.

Mrdby · #13 10-18-2007, 08:45 PM

When i refresh using Mozilla..it gives me a grey screen and then goes back to normal.Why is that?

PoetJA-1975 · #14 10-18-2007, 11:40 PM

Interesting share = Thanx

Jacquii.

Lizard King · #15 10-19-2007, 02:29 AM

<a href="https://vborg.vbsupport.ru/showthread.php?t=123719" target="_blank">https://vborg.vbsupport.ru/showthread.php?t=123719</a>

Analogpoint · #16 10-19-2007, 03:23 AM

Quote:

Originally Posted by Milad

Very good.

But, will be there a conflict with the <body onload="bla bla bla">?

No.

Quote:

Originally Posted by Milad

Is it compatible with all browsers? especially IE6-7 FF1.5 FF2.

Yes.

Quote:

Originally Posted by Mrdby

When i refresh using Mozilla..it gives me a grey screen and then goes back to normal.Why is that?

This doesn't affect the display of your forums layout in any way.

Quote:

Originally Posted by Lizard King

https://vborg.vbsupport.ru/showthread.php?t=123719

That's a classic case of using a bulldozer to knock over a molehill. You have to upload a Javascript file, and a php file, as well as install the product. It uses AJAX where AJAX is not needed. It makes you run a hacked version of vB's cron.php file. It doesn't work with vBadvanced, vBdruapal and others. I'm not sure how it deals with users who don't have Javascript enabled. This mod has none of those problems. Shall I continue?

PoetJA-1975 · #17 10-19-2007, 06:43 AM

was waiting for the above statement to install

Thanx for the share!

Jacquii.

succo · #18 10-19-2007, 08:33 AM

ehm... to make it work under vbadvanced (i mean, the portal) i had to subst cron.php in the plugin with the full path to cron, or it was searching for cron in the root folder, obviously not finding it

btw, yes, this seems to speed up loading very much, thanks!

Mecho · #19 10-19-2007, 09:59 AM

would u plz someone explain how we should kno that it works or not ?? i mean where we can find any detail that how it works in our board and ... !!

thanks

Analogpoint · #20 10-19-2007, 02:02 PM

Quote:

Originally Posted by succo

ehm... to make it work under vbadvanced (i mean, the portal) i had to subst cron.php in the plugin with the full path to cron, or it was searching for cron in the root folder, obviously not finding it

btw, yes, this seems to speed up loading very much, thanks!

It has the same behaviour as the default vB cron image, which also wouldn't be inserted into vBa pages.

Quote:

Originally Posted by Mecho

would u plz someone explain how we should kno that it works or not ?? i mean where we can find any detail that how it works in our board and ... !!

thanks

View your cron log and see if the scheduled tasks are being run.

Analogpoint · #21 10-19-2007, 02:33 PM

Quote:

Originally Posted by succo

ehm... to make it work under vbadvanced (i mean, the portal) i had to subst cron.php in the plugin with the full path to cron, or it was searching for cron in the root folder, obviously not finding it

btw, yes, this seems to speed up loading very much, thanks!

I've updated the product (version 1.0.1) to use $vbulletin->options['bburl'] so that it will have better out-of-the-box compatibility with vBa and other portal scripts. If you're not using a portal script, there's no reason to update, but it also won't hurt anything if you do update.

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