How to test a url resource exists in squid cache or not

cachesquid

I use squid to cache some big files.
And I want to make sure if these big files are in squid's cache.
But I just don't want to download the file, then go to squid log to find this.
That will take too much time and squid resource.

Is there are cheap method to check this?
I can't find any method in squidclient, squid cache manager, and wget to do this.

Best Answer

Maybe a bit late for the OP, but can't you just make a HEAD request for the large resource and check the response headers to see if you got a cache hit?

Related Solutions

Squid or Other HTTP Caches with SSD Cache Store

We've been using varnish on ssd drives for the last 9 months, it has worked extremely well for us. We previously used a squid memory only cache with a carp layer. It worked, but memory fragmentation was a real problem requiring frequent restarts. Squid 2.x also will only use one core which makes it rather inefficient on current hardware.

For our site, which is very cache friendly, we see about about 10% cpu usage on an 8 core machine serving 100Mbit/s of traffic. In our tests we run out of bandwidth before we hit cpu limits with 2 1Gb ports.

I do have some advice for running varnish with an ssd cache.

Random write performance really matters. We tried several vendor's for ssd drives before settling on the intel x-25m. We've seen some post as little as .1MB/s for 4k random writes, we get 24MB/s 4k random writes with the x-25m.
Raid0. The cache in 2.0 is not persistent, so no need to worry about redundancy. This does make restarts hurt, but those are rare. You can do things like load a new config and purge objects without restart.
mmap mode. The varnish cache can be mmap'd to a file or use swap space. Using swap has not worked well for us, it tends to use more i/o bandwidth to serve the same amount of traffic. There is a 4 sector readahead in the linux swapin code, we wrote a patch to remove this but have not tried it in production.
Deadline scheduler. With 2.6.28+ this is ssd aware and performs well. We tried noop but found that deadline was fairer as i/o bandwidth becomes limited.
Disable read ahead. Since there is no rotational delay, no point in reading extra data just because you might need it. i/o bandwidth is precious on these things.
Run 2.6.28+. mmap of a lot of space on linux gives the memory manager a good workout, but the split lru patches help a lot. kswapd cpu usage dropped a lot when we updated.

We've posted our vcl file as well as several tools we use with varnish at link text. The vcl also includes a neat hack implementing a very fast geoiplookup server based on the maxmind database.

How to prevent Squid from caching HTML pages with the text/vnd.wap.wml MIME type

It would be better to adopt one of the no-caching methods on the server-side... but you can setup an ACL & deny caching on it... i.e.

acl NOCACHE rep_mime_type text/vnd.wap.wml
no_cache deny NOCACHE

(I think it's rep_mime_type ... might be req_mime_type...)

Best Answer

Related Solutions

Squid or Other HTTP Caches with SSD Cache Store

How to prevent Squid from caching HTML pages with the text/vnd.wap.wml MIME type

Related Topic