Cross platform repeatable RTS

[cgibbard@…]

This bug seems to be reproducible on Linux, Windows, and OpenBSD, at least.

In the included package, run ./build.sh, which will build and run a program as follows:

ghc -lz -threaded --make unstuff.hs -o unstuff
./unstuff trace.dat

The program forks a lot of OS threads. After several seconds of running, it dies with:

unstuff: user error (ORANGE ALERT: 0s, 4s, SrvServerInfo, ix1: 6, size: 49722)

unstuff: internal error: scavenge_stack: weird activation record found on stack: 64384
    Please report this as a bug to glasgow-haskell-bugs@haskell.org,
    or http://www.sourceforge.net/projects/ghc/

The first message is simply an error printed by the program reporting that it took too long to compute a result.

[cgibbard@…]

I can't seem to attach the test case, even after splitting it into smaller pieces, so I'll make it available at  http://vx.hn.org/autoshare/repro.tar.bz2

[simonmar]

Now fixed, in both HEAD and STABLE. There was a problem with the state in which we leave the stack after a thread has been killed by an unhandled exception.