bug in compacting GC
simonmarhaskell at gmail.com
Mon Feb 6 09:20:17 EST 2006
Bulat Ziganshin wrote:
> Hello ,
> yes, i found this famous "-c" bug! the humor of situation is what
> easiest way to got this bug is to run ghc itself! :) it seems that
> noone except me tried this ever. i just found that any large enough
> module raises this error!!! that, for example, results of compiling
> Data.Map module:
>>ghc Map.hs -cpp +RTS -c
> ghc.EXE: internal error: update_fwd: unknown/strange object 39004
> Please report this as a bug to glasgow-haskell-bugs at haskell.org,
> or http://www.sourceforge.net/projects/ghc/
> ghc 6.4.1/mingw32. the error is absolutely reproducible, so at least
> now we had case, even lot of cases :)
> or you wanna a smaller program? :)
I think this may be a different bug - I can reproduce it, but not with
the current STABLE branch. It is probably the freeze/thaw bug that was
fixed after 6.4.1.
However, I've still seen strange crashes in STABLE when using +RTS -c.
We build stage 3 of the nightly build with +RTS -c every night, and
right now we aren't getting any crashes, but a few weeks ago we were.
When I looked into it, I couldn't get a deterministically repeatable
crash - every tiny change made the crash go away.
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