Seems like it could be a compiler or GC bug (or a bug with the safe pointing interaction between compiler and GC).
It's possible that a write to the counts array is misdirected so it doesn't occur.
Is the sum of counts always less than the sum of vals?
On second thought, if counts is mmapped, GC might not be in play. But a similar bug might occur due to state being lost during an On-stack-replacement of one of the loops.
I'm not familiar with deep jvm stuff, but is there a way to ask the jvm for a compilation log to see if JIT OSR is happening?
It's possible that a write to the counts array is misdirected so it doesn't occur.
Is the sum of counts always less than the sum of vals?
On second thought, if counts is mmapped, GC might not be in play. But a similar bug might occur due to state being lost during an On-stack-replacement of one of the loops.
I'm not familiar with deep jvm stuff, but is there a way to ask the jvm for a compilation log to see if JIT OSR is happening?