A possible signal handling bug in Solaris

I know that combining threads and signals is a bad idea, but I just couldn't resist the temptation. It seemed like a nice solution until I've hit what seems to be a possible signal handling bug: sometimes the signal is not delivered on the alternate signal stack, even though a thread has requested so. You can read the full description here. I wonder whether I'll get a reply. In the mean-time, I'm abandoning threads in favor of multiple processes operating over a large shared memory segment.