id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
5226	<<loop>> with -threaded -feager-blackholing, but only sometimes	dreixel	simonmar	"While benchmarking the performance of GHC's SMP parallelism, I ran into an issue where (rarely) a test would fail with `<<loop>>`. I tried hard to reduce this to a single file, which I am attaching to this report.

To reproduce, compile the program with `--make -threaded -feager-blackholing -rtsopts -O1` and run multiple times with `-Nm` with `m>=2`. In my case, using `N8` (on a machine with 8 cores), I once got the error after 35 tries, but sometimes it takes thousands of attempts. I'm also attaching a bash script to compile and run the test repeatedly.

Tested with current HEAD, built on a Intel Xeon E5320, ""perf"" settings without dynamic linking. But I think I also encountered this behavior in GHC 7.0.3."	bug	closed	high	7.0.4	Runtime System	7.1	fixed			Unknown/Multiple	Unknown/Multiple	Runtime crash