STOP state in top + segmentation fault and core dump?

[Pierre-Luc Drouin]

Hi,

When I run many heavily multi-threaded (1000+ threads/process) and 
memory intensive (1800 MB+/process) processes on FreeBSD 8.0 amd64, some 
of them get in STOP state in top and then seg fault and core dump. Are 
stop states in top caused by seg faults or it is the OS that stops the 
processes because they exceed some limit? I do not see any message about 
any limit being exceeded. The machine has 12GB of memory so it should  
be able to sustain 4 processes using 1800MB each of memory I guess (I 
have 12 GB of swap space anyway but it stays unused). Everything runs 
fine if I run a single process and I have never encountered such 
problems when running these on Linux. Anyone has an idea?

I am using the default limits right now:
 >limit
cputime      unlimited
filesize     unlimited
datasize     33554432 kbytes
stacksize    524288 kbytes
coredumpsize unlimited
memoryuse    unlimited
vmemoryuse   unlimited
descriptors  11095
memorylocked unlimited
maxproc      5547
sbsize       unlimited
swapsize     unlimited

Thank you!