Hi everyone,
All this talk on Threads has encouraged me to relate a problem I'm having with Java3D
and Threads. Hopefully it's something I'm doing wrong that I can fix.
My application essentially animates an articulated arm (a TransformGroup for each
joint). The user drags a JSlider which sends data over a socket to a C application
(historic kin/invkin engine that i must use), which processes the data quickly and
sends joint data back over the socket to my Java app.
I have a few threads involved, but here's my basic scheme:
1) One thread continually reads the socket and updates a set of transforms in my
Manipulator object. These transforms are not placed in the live Transform groups.
// This method is called by the socket-reading thread with new joint values
void synchronized Manipulator::setJointValues(double[] newJointValues)
{
for (int j = 0; j < jointTransforms.length; j++) {
jointTransforms[j].rotX(newJointValues[j]);
}
}
2) A behaviour runs every 31ms and calls a synchronized "latchJoints" method on the
Manipulator object which places the transforms into the live TransformGroups.
// This method is called from processStimulus of the behaviour
void synchronized Manipulator::latchJoints()
{
for (int j = 0; j < jointTransforms.length; j++) {
jointTG[j].setTransform(jointTransforms[j]);
}
}
This works fine for a while, then eventually stalls the Java3D Behaviour thread. The
socket-reading thread continues. It's worse with a smaller scene.
I have tried using the InputDevice mechanism but it had the same problem (albeit an
older version of Java3D). I have also tried waking the behaviour after every frame,
but it's much worse.
Alas, when I run the app in a debugger it never crashes! Typically Threading problem,
right?
Unfortunately my app is too huge to be useful as a test app and I haven't the time
right now to pare it down, but if anyone sees an obvious blunder on my part I'd
appreciate some insight. I'd appreciate debugging strategies too.
Thanks everyone,
Josh
----------------------------------------------------
Joshua L. Richmond, BASc, MSc.
Systems Engineering (R&D)
MD Robotics
9445 Airport Rd, Brampton, ON, Canada
(905) 790-2800 x4332
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