[ODE] SIGSEGV in dSolveLCP() at ode/src/lcp.cpp:1137

[Olivier Michel]

Thanks for the replies. However, I cannot work around this problem:

(1) I tryed increasing the heap size under Linux: "ulimit -s unlimited" 
to increase the heap size from 8192 to unlimited, but that didn't helped 
(might be ineffective).

(2) I tryed to use dWorldStepFast1 instead of dWorldStep, but then all 
my bodies are falling down breaking the joints I set. I set all the 
masses to 1 to try to avoid this problem but it didn't change anything 
(still collapsing the model).

It seems the simulation works with fine dSolveLCP() when the n parameter 
remains below ~200. However, when my two humanoid robots hit each other 
(~44 bodies connected through joints), n reaches 384 and the SIGSEGV 
occurs...

I will try to replace all the ALLOCA from lcp.cpp to dynamical 
allocations / desallocations as it seems to be the only way to work 
around this problem, isn't it ?

If it works, may I contribute this alternative to the ODE cvs if this is 
usefull for others ?

-Olivier

Martin C. Martin wrote:

> Search the docs for "stack," and you'll see at least two things you 
> can do.
>
> - Martin
>
> Olivier Michel wrote:
>
>> Hi there,
>>
>> I have a bug in my ODE simulation which occurs in ODE dSolveLCP() 
>> function after a while and when two objects enter in collision, but I 
>> don't understand why a SIGSEGV occurs while creating a stack object 
>> in ode/src/lcp.cpp:1137. Here is what I get from gdb (under 
>> Linux/woody):
>>
>> Program received signal SIGSEGV, Segmentation fault.
>> [Switching to Thread 1024 (LWP 6180)]
>> 0x0817333e in dSolveLCP (n=351, A=0xbfef1630, x=0xbfeef480, 
>> b=0xbfeeff90,
>>   w=0xbfeee970, nub=0, lo=0xbfff9af0, hi=0xbfff8fe0, findex=0xbfff8a54)
>>   at ode/src/lcp.cpp:1137
>> 1137      dLCP lcp 
>> (n,nub,A,x,b,w,lo,hi,L,d,Dell,ell,delta_w,state,findex,p,C,Arows);
>>
>> How can the creation of a dLCP object cause a SIGSEGV ? Shall I try 
>> to replace it by something like:
>>
>> dLCP *lcp = new dLCP(...);
>>
>> Any hint would be appreciated.
>>
>> -Olivier
>