Multithreading

[tony]

Hi,

I've got the following code which mimicks a trail sop:

SOP_TrailIfExists::cookMySop(OP_Context &context)
{
fpreal t = context.getTime();
fpreal f = context.getFloatFrame();
fpreal new_t;
const GU_Detail *current_frame_gdp;
const GU_Detail *trail_frame_gdp;
GU_Detail blank_gdp;
GU_Detail trail_gdp;
OP_Context trail_context = context;

//get trail length and increment amount from UI
fpreal len = LEN(t);
fpreal inc = INC(t);

// Lock the input context
if (lockInput(0, context) >= UT_ERROR_ABORT)
return error();

//get the geometry
current_frame_gdp=inputGeo(0, context);

//start copying
gdp->copy(blank_gdp, GEO_COPY_START);
//copy current frame
gdp->copy(*current_frame_gdp, GEO_COPY_ADD);

//unlock the context
unlockInput(0);

//do the trail
for(int i = 1;i<len;i++)
{

// This is the frame number we want to evaluate
new_t = f-(i*inc);

// The context takes seconds, not frame, so we convert.
new_t = OPgetDirector()->getChannelManager()->getTime(new_t);

// Adjust our cooking context to reflect this
trail_context.setTime(new_t);

// Lock the input context
if (lockInput(0, trail_context) >= UT_ERROR_ABORT)
return error();

//get the geometry
trail_frame_gdp=inputGeo(0, trail_context);
// copy the geometry
gdp->copy(*trail_frame_gdp, GEO_COPY_ADD);

}

//end copying geometry
gdp->copy(blank_gdp, GEO_COPY_END);

//unlock the input
unlockInput(0);


return error();
}
[/CODE]

I'd like to be able to make it run on multiple threads, but I'm a bit unsure about how to go about it. I've had a look at:

http://www.sidefx.co...ingChildThreads

which seems to suggest I need to wrap it all up into a class and use the UT_ThreadedAlgorithm THREADED_METHOD options. But then I looked at the slides in: $HFS/toolkit/slides/HDK12_Intro.pdf

and they mention the UTparallelFor option. My main questions are:

1. Which one should I go for?

2. Will I need to wrap all of my code into a class or can I just put the for loop into a seperate function and thread that function?

Cheers,

Tony

[Guest mantragora]

If I remember correctly PDF mentioned both methods. It wasn't specified why one is better over other so I suppose both are equally good.

PS. I have somewhere example of threaded code, not made by me, but I can't find it now.

Edited July 19, 2013 by mantragora

[graham]

I'm skeptical that this could actually be multithreaded. Houdini doesn't really support threaded network cooking which is essentially what this could would be doing. I suppose it's worth a shot, but I wouldn't expect any gains and there might even be some crashing.