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#4452 – [BUG] Cache content being dumped in website on line 1

Posted in ‘sh404SEF’

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Thursday, 04 January 2018 05:13 UTC

chizuoka

Hello,

I found a very serious bug in SH404. One day it happen suddenly that when i open my website, the whole site was filled with garbage, and because there was so much of it, it caused the site to load forever. When it finally did load, the content was below.

Upon further investigation it turned out for some reason SH404 dumped the entire content of it URL cache file from line 1 onward of the page code. (Please see screeenshot) The issue was only resolved by manually deleting the cache file from the filesystem.

I also have more than one domain pointing to the same files, but other domain is fine...
www.xxxx.com (cache was dumped)
www.xxxx.co.uk (ok)
www.xxxx.com.sg (ok)
www.xxxx.com.au (ok)

So it seems it was like it saw the .com so it dumped ... but if it was not .com it did not. Just some debugging to help you out. Is there any impace to sh404sef if multiple domains access the same files?

Thursday, 04 January 2018 08:06 UTC

wb_weeblr

I found a very serious bug in SH404.

You did not find any bug. This happens on some servers when they cannot cope with the speed write required fro caching the URLs (related to the traffic on the site and the URL creation rate). On such servers, this can be prevented by disabling the "Url disk cache feature", under the "Advanced" tab of sh404SEF configuration (or move to a faster server of course).

Rgds

Thursday, 04 January 2018 08:46 UTC

chizuoka

Should I use memcached then to avoid this? Will SH404 recreate the cache in memcache should the memcache empty its memory for some reason.

Thursday, 04 January 2018 09:46 UTC

wb_weeblr

Hi

You can use memcache, or just disable this feature (it is now off by default), which is less important nowadays with more modern servers.

Rgds

Thursday, 04 January 2018 10:42 UTC

chizuoka

why would you say that? In your tooltip you say it improves performances significantly?

Thursday, 04 January 2018 12:27 UTC

wb_weeblr

Hi

Because it depends on the server. It will improve perfs on lower end MYSQL servers, and it is generally a good thing but on most servers these days, and for most sites, it's not needed. And as some servers have the problem you are facing, I now recommend to switch it off, as it's not worth the trouble for most sites.

Rgds

Monday, 08 January 2018 11:20 UTC

chizuoka

thanks then.

Monday, 08 January 2018 11:20 UTC

chizuoka

One last q.. would memcached as cache improve it considerably

Monday, 08 January 2018 12:31 UTC

wb_weeblr

Hi

I can't really say, it depends entirely on the number of URLs on your site, the URLs distribution on your pages and your site visit patterns by users. Those are the factors that will affect whether URLs are taken from cache or recreated. High cache hit rate will certainly speed up the site, but that's not related to memcache vs file really.

What can make a difference is whether you use the URL cache or not at all. So did you see a vast slowdown since you disable the "Use URL disk cache" feature? if so, it might be worth replacing the file backend by memcache. If not, then maybe not worth the trouble.

Rgds

Tuesday, 23 January 2018 05:34 UTC

system

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