On Mon, Aug 3, 2015 at 11:58 PM, Bart Schaefer wrote:
}
} If you can get a stack trace from the deadlocked zsh, that would be
} helpful.

I've tried to produce a stack trace on OS X with dtruss, but it slows
down zsh too much and I am never able to reproduce the deadlock
scenario. I have however managed to get a dump with strace on Gentoo
(also here, I've applied the patch discussed earlier), see attachment.

}
} A stack trace from the SIGILL's zsh might also be helpful, but that is
} less likely.

I will see if I manage to do it, but even without a debugger, I have
rarely seen this error.