Wireshark · Wireshark-dev: Re: [Wireshark-dev] Memory consumption in tshark

[Anders Broman <a.broman@xxxxxxxxxxxx>]

Joerg Mayer skrev 2013-08-27 23:24:
> On Tue, Aug 27, 2013 at 05:09:19PM -0400, Evan Huus wrote:
> > > IIRC, two-pass allows for most/all of the reassembly/request-response
> > > stuff,
> > > which we want to do sometimes. Any ideas why we have to keep some
> > > information
> > > indefinitely?
> > Two-pass requires us to keep *all* the state around through the first pass
> > so that it is available during the second pass (at which point it can be
> > discarded).  Even in single-pass mode, there is some state that we can't
> > always immediately discard. If I see a fragment of a TCP message then it
> > doesn't make sense to discard that until the other fragments have arrived
> > and been reassembled. If I see a request, I probably need to keep state
> > from that request until the response (which may never show up).
> >
> > We already do reassembly and a lot of other stateful work in single-pass
> > mode. The only thing two-pass mode provides is the ability to "see the
> > future" (for example, saying: this request has a response 5 packets later).
> So (assuming we really free everything we could already) could add a
> possibly configurable foresight horizon of 10000 packets. If a packet
> number is older than 10000 packets, forget it?
I haven't really looked but we do keep the reassembled fragments around 
even in tshark as there is no
mechanism to discard them selectively if run by tshark as opposed to 
wireshark and that's the really big memory eater I would think.
Regards
Anders