yade-dev team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxxxxxx>]

Hi Robert,
Congrats for finding the bug and thanks for fixing.

On 02/13/2018 11:55 PM, Robert Caulk wrote:
> the issue was compiler related. GCC 5.4 on ubuntu 16.04 initialized 
> factorizeOnly to false by default, while GCC 7.2 on ubuntu 18.04 did 
> not do this.

That's a good example of "undefined" behavior when using non-initialized 
variables... Definitely a nasty bug.

> Therefore, the only necessary change ended up being the explicit 
> initialization of factorizeOnly=false.
Indeed. :)

> In addition to the bug fix, I edited the solvers so flow.useSolvers=3 
> and 4 can now be used with the default CPU build. I can confirm that 
> flow.useSolver=4 enables multicore CPU factorization, while 
> flow.useSolver=3 sticks to 1 core factorization :-).
Excellent. FYI multicore CPU factorization was faster than single core 
in my benchmarks, but multicore solve phase (using the factorized form) 
was not, it was even a bit slower than single core. Hence the distinct 
attributes  numFactorizeThreads and numSolveThreads.
Cheers

Bruno