id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
4811	Internal error: throwTo: unrecognised why_blocked value	mitar		"I am getting this error:

{{{
internal error: throwTo: unrecognised why_blocked value
    (GHC version 7.1.20101124 for x86_64_unknown_linux)
    Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
}}}

Sadly I was unable to make a simple test case. It is a program build upon [http://hackage.haskell.org/package/Etage Etage] with heavy FFI (X11, webcam capture, [http://hackage.haskell.org/package/NXT NXT interface]) and threading.

Problem is reproducible. It does not happen always, but in let's say 10 % of program runs. Program is compiled with `-threaded -O2` and it happens only if I pass `+RTS -N2` (or bigger `-N`) parameter. With only `-N1` it seems it does not happen.

If somebody wants I can send him/her whole program. You do not need a webcam or NXT as this happens when there is nothing connected to the computer and program prematurely exists because of this.

Or you can guide me what and how should I debug."	bug	closed	high	7.0.2	Runtime System	7.1	fixed		mmitar@…	Unknown/Multiple	Unknown/Multiple	Runtime crash