Higher-priority processes are not scheduled

[LinqLover]

Higher-priority processes are not scheduled

[fniephaus]

Maybe you are right though, not sure why primitiveYield doesn't resolve the problem. Looks like I may need to take another look at the primitive.

[fniephaus]

#busyWait uses [Time utcMicrosecondClock >= proceedTime] whileFalse, which is a block that includes primitive calls only. Therefore, this is a different form of the issue documented in #104.

[LinqLover]

But Processor yield didn't help, so isn't there something wrong with primitiveYield?

[fniephaus]

But Processor yield didn't help, so isn't there something wrong with primitiveYield?

No, as you mentioned, Processor yield is a primitive calls as well so the loop body remains trivial in the sense that there is no actual send that would trigger a check for interrupts. As a consequence, TruffleSqueak's bytecode loop will not be interrupted until the loop is exited. In 581730f, I drafted an idea that adds interrupt checks to the bytecode loop for such trivial loops. While this fixes both #167 and #104, we need to run the benchmarks to see how much it impacts peak performance.

[fniephaus]

Nope, my first comment was correct: you put the yield into busyWait and not into the block itself. Since the block contains no actual sends and no explicit yield, the bytecode loop is not exited until the timer expires. So indeed, we need to make sure to check for interrupts in such trivial loops.