[Thad House]

Originally Posted by virtuald

Not true for Java... if you look at the Java code most of the methods are marked as 'synchronized'. The DriverStation thread task calls getData() which goes into HAL a bunch so it's probably not particularly fast (JNI overhead) -- and it's also marked as synchronized, so they'll all block each other in various ways.

I didn't realize that C++ did this differently though, very interesting.

Yeah Java does it differently. I have some patches that bring Java and C++ closer together in Gerrit, but they are not going to be merged until after the season. They also use ReaderWriterLocks and double buffering in order to reduce memory usage and increase speed as well. Also Javas GetData doesn't get the status data anyway, so those are not cached and called individually.

Also, its not HAL or JNI overhead. For some reason, any call into the FRC_NetworkCommunication library takes 0.2-0.3ms. Doesn't matter which language, just entering those takes the time. So when the DriverStation Robot Mode check methods are called, every single time they enter that library, and every single call takes 0.2-0.3ms. If you run a loop in Teleop, that in a for loop calls DriverStation.IsEnabled 300 times, that entire sequence will take about 60 ms to run.