Reload reload reload reload.

May 31, 2008 12:04 PM

Why on some web hosts do uploaded file changes not appear immediately?

On some web hosts I've used in the past, like my university's, I can upload a changed file by FTP but not see the changes through a browser for several minutes. Clearing cache, reloading the page, even uploading a *completely* different file with the same name fails. I have to wait several minutes until the server finally believes it's a new file. I assume it is some setting on the server to conserve resources?

posted by wastelands to computers & internet (4 comments total)

Sounds like the problem I ran into a while back.
posted by MrMoonPie at 12:31 PM on May 31, 2008

Sometimes there is a cache on the server side as well, especially if the pages are dynamically generated. That way, commonly loaded pages can be cached for some set amount (could be minutes, could be hours, could be days) so that there isn't a load on the server or the database (which is what happens when pages are dynamically loaded).

Probably once the new content does show up, that's when a new cache has been generated.
posted by kosmonaut at 1:17 PM on May 31, 2008

Try adding <META HTTP-EQUIV="CACHE-CONTROL" CONTENT="NO-CACHE"> to your page - in theory this will prevent caching, but it's still up to the server to respect it.
posted by nicwolff at 3:42 PM on May 31, 2008

I don't know if this is your situation, but some installations use a cluster of identical servers, designating one as the master which receives all http requests, then hands them off to other servers in the cluster according to which has the smallest load (or by some other algorithm). All file changes are made on the master, and the new file(s) is then replicated across the rest of the servers. It may be that the replication is performed only once every n seconds/minutes, or at specific times, etc.
posted by davcoo at 6:41 PM on May 31, 2008