[Plugin: Broken Link Checker] 0.9.5 problems

I doubt it’s a plugin conflict, but I can’t say I’ve got a better idea. Debugging performance problems tends to be tricky. What’s your PHP version and how many links do you have?

WP 3.01 multisite. PHP 5.3. 250 links.

Multisite mode is not officially supported by Broken Link Checker. The plugin hasn’t ever been tested for compatibility with setups like that, so mysterious bugs are to be expected.

It’s a small miracle that it worked at all on your site.

Got it. I must have been very fortunate, in that BLC worked great on MU and multi-site up to the most recent update.

Here’s an official request for multi-site support in future.

By the way, that’s why I reported the plugin as broken … but I didn’t ask: does BLC Pro work with multisite?

No, right now neither version works with WPMU. I’ll see what I can do about this when I work on the next release.

Ok. Thanks ;(

Err, I just looked into this problem and, surprisingly, I can’t find anything that would prevent it from working on WPMU. Perhaps you have some more clues? Server error logs, maybe?

Let me activate it again and catch the server logs.

I tried activating three ways:

Automatically, then network activate – white screen on all backends
Automatically, then single-site activate – first site works fine, next one, white screen
Manually in /mu-plugins/ with no effect at all.

My server access logs didn’t show anything unusual. If there’s a plugin conflict, I’ll try disabling them in development.

Do the plugin’s DB tables get created and populated when the plugin is activated on the first/next site? You can identify the tables by the “blc” part of the table name. If the tables are created, do they contain any data?

Bingo.

Since I’d deleted the blc plugin files to get back my admin screens, there were left-over blc database tables, so I deleted all of them and started over.

Good news: now, no white screens.

I tried a “network activate” and in my “next” site, I received the following error:

“Database error : Table ‘TABLE-NAME.wp_12_blc_links’ doesn’t exist”

So, I deactivated, and reactivated one site at a time. First site worked great. Subsequent sites timed out; perhaps the script was busy with the initial (major) link scan, because about 1 minute later, I refreshed the page and all of the links were accounted for (more than 500).

Overall, everything slowed down for about 10 minutes, probably during initial checking, and timed out. Then, as I activated each site, working great!

So, initial questions:

– Is there any way to throttle initial checking so it doesn’t slow down the whole instance, causing timeouts?

– Would it then be possible to network activate?

That said, now that the initial check is done, all is working great (with site-by-site activation)!

Good to hear that.

I agree that having a way to throttle the initial scan would be useful, but so far I haven’t been able to come up with a way to do it. There’s a “Server load limit” setting in Settings -> Link Checker -> Advanced that you could tweak, but it won’t help much in this case because the first scan will already be running by the time you get to that settings screen.

I’ll need to think about this.

I have found two possible causes for the time outs I was experiencing when activating BLC on a site with many links.

First, I replaced “Reveal IDs for WP Admin” with “Simply Show IDs” and the backend screens are being delivered much more quickly.

Second, I increased the default timeout in Firefox, which appears to have been shortened in a recent update.

So far, so good. When I can, I will deactivate BLC for one site with many links, delete tables, and reactivate, and see whether I get the timeouts on the initial processing.

You can also try the latest dev. version. It fixes a bug that would cause the plugin to perform a lot of redundant DB scans when it gets deactivated and then immediately re-activated (as when upgrading). The total number of queries issued during activation has also been trimmed down a bit.

(Of course, the dev. version could contain a couple of brand new bugs…)