BSD/etc Tor servers? (was Re: Tor takes too much RAM)

[Roger Dingledine]

On Fri, Nov 30, 2007 at 11:35:23PM -0600, Scott Bennett wrote:
>      However, I would be interested in knowing why I see this:
> 
> -rw-------  1 _tor  _tor    365907 Nov 30 23:10 cached-consensus
> -rw-------  1 _tor  _tor  39096827 Nov 30 23:11 cached-descriptors
> -rw-------  1 _tor  _tor    174297 Nov 30 23:17 cached-descriptors.new
> 
> The cached-descriptors file contains *six* differing descriptors for my tor
> server, five of which are obsolete.  What gives?

The apparently obsolete ones are valid for some v2 networkstatus that
is still live. That is, there might be a client out there with an old
but still valid v2 networkstatus that lists one of those old descriptors.

So since you're a cache, you need to keep copies of those around too,
in case some client asks for them.

You discard them once the networkstatus that listed them becomes obsolete.

See https://www.torproject.org/svn/trunk/doc/spec/dir-spec-v2.txt

Once the v2 directory design disappears in favor of v3 (which is used
in the Tor 0.2.0.x branch), the number of descriptors the caches will
need to cache should go down.

https://www.torproject.org/svn/trunk/doc/spec/dir-spec.txt

>  Are the obsolete descriptors
> taking up memory in the tor address space?  Seems to me that 1300 - 1700 tor
> server descriptors should not require over 37 MB, but if they appear multiple
> times, I suppose that would account for the waste.

No, Tor mmaps that file, so it isn't all in memory.

--Roger