[Iftop-users] CPU use bug?

[Alex Page]

Hello,
I am seeing strange behavior recently in iftop on Ubuntu (x64, 12.04 and 
13.10).  With Port Display disabled, iftop simply uses more CPU than 
normal (say, 20% instead of a negligible amount).  Then, when Port 
Display is enabled, CPU use goes straight to 100% and iftop becomes 
unresponsive.

This behavior started sometime in the last few months, and occurs on 2 
of the 4 Ubuntu machines that I've tested it on.  I compiled iftop 0.17 
and 1.0-pre2 from source and observed the same behavior as the 
precompiled version (1.0-pre2 from the Ubuntu repo) on these computers.

I cannot figure out what is unique (other than physical hardware) about 
the 2 machines that still work, except that they use 3.2 and 3.6 kernels 
(vs. 3.5 and 3.11 on the machines that don't work).  So maybe there's a 
network driver issue?  I checked the version numbers of libc6, 
libncurses, libpcap, and libtinfo (all the dependencies I know of) and 
they are the same on 1 of the working machines vs. 1 of the non-working 
ones.  And iftop worked properly on all of these machines until some 
relatively recent update.

So, iftop is completely unusable on at least 2 of my computers.  Can 
anyone recommend further troubleshooting steps that I could take to 
isolate this problem, preferably without rebooting?  Are there any other 
library versions I should check?

Thanks,
Alex