We (CricInfo) are looking to deploy pound as a reverse proxy across a number 
of areas of our site. As a first stage of this I deployed the latest Debian 
pound package (Version: 1.7-1) on a single P4 server running a 2.6.7 kernel 
with 512Meg RAM in front of our image servers (three thttpds serving small 
site graphics such as the ubiquitous spacer.gif).
All ran very well while we we receiving fewer than around 100hits/sec but as 
deman rose above this level we rapidly started to see lines such as

Aug 16 08:56:26 stewart pound: HTTP pthread_create: Cannot allocate memory

in syslog. These occuring mainly in large blocks (up to 80 consecutive 
lines). Between these blocks we were still successfully serving around 100 
hits/sec but over time the error lines start to overwhealm the good lines 
forcing me to abandon the test as complaints of incomplete webpages started 
to come in. We had not reached limits of physical RAM or worrying server 
loads at this point. After redirecting the DNS away from the pound and the 
numbers of requests falling it took a very long time for these error lines 
to dissappear.
Does anyone have any experience of this problem and/or any suggestions on 
changing anything before a recompile and a new test.
Jeff
--
Jeff Green
Systems Manager, Wisden CricInfo Limited