Re: nmap 5 memory usage

[David Fifield <david () bamsoftware com>]

On Sun, Nov 08, 2009 at 12:15:39PM +0200, Dimitrios Apostolou wrote:
> Hello nmap hackers,
>
> I just run latest nmap on an old PC with 128MB RAM and a few other 
> programs running. The system slowed down significantly and started  
> swapping like crazy.
>
> I'm just reporting it here because it seems that system requirements have 
> been significantly raised without anyone noticing (if this is intentional 
> please just ignore me). By pmap'ing the process I got about 70MB of  
> anonymous memory mappings. My command line was as simple as 'nmap -A  
> $IPADDR'. What do you think?

I tried this command with the Massif memory profiler. For me it grows to
about 70 MB too. It turns out that almost all of this (over 80%) is from
parsing the nmap-os-db file.

http://www.bamsoftware.com/wiki/Nmap/Memory#a20091120

The OS database has been growing, but the bigger cause is probably the
increase in the size of each test value, which was increased from 128 to
256 in r11074 in November 2008. All test values are allocated the same
amount of memory, which is very wasteful because most values a shorter
than 10 bytes. This is another target of the memory use reduction
campaign.

David Fifield
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