[darcs-users] "darcs get" crashes (usually)

David Roundy droundy at abridgegame.org
Wed Jul 21 10:04:08 UTC 2004

On Tue, Jul 20, 2004 at 01:45:27PM +0200, Martin Schaffner wrote:
> I have a darcs repo which I can't "get", neither on Windows nor on Mac OS 
> X. On the mac, darcs usually does a "Bus error", sometimes a "Segmentation 
> fault", and rarely it succeeds. The error happens while writing the dots 
> after "Copying patches...", not always at the same place. It is in 
> relation to garbage collection, as can be seen from this gdb session on 
> Mac OS X:
> (gdb) r get /Volumes/bla/cpp/repo/
> Starting program: /private/tmp/darcs get /Volumes/bla/cpp/repo/
> Reading symbols for shared libraries +... done
> Copying patches...
> ..................................
> Program received signal EXC_BAD_ACCESS, Could not access memory.
> 0x0029d498 in evacuate ()
> (gdb) bt
> #0  0x0029d498 in evacuate ()
> #1  0x0029eac4 in scavenge ()
> #2  0x0029c2b8 in GarbageCollect ()
> #3  0x00266a48 in schedule ()
> #4  0x00267080 in waitThread_ ()
> #5  0x00266f98 in scheduleWaitThread ()
> #6  0x0027fbec in rts_evalLazyIO ()
> #7  0x0023b7d4 in main ()
> #8  0x00001ca4 in _start (argc=3, argv=0xbffffd8c, envp=0xbffffd9c) at /
> SourceCache/Csu/Csu-46/crt.c:267
> #9  0x00001b18 in start ()
> (gdb) 

Sounds like a problem with mmap and your volume, since mmapped files get
munmapped during the garbage collection.  Can you try running with a darcs
compiled without mmap? Is this a mounted windows volume? If so, that may be
the trouble.  On windows, mmap doesn't work right, since you can't maintain
an mmap to a file after it is deleted.

As to why it crashes on windows, I have no idea, since I hope your windows
darcs is compiled without mmap enabled.  My guess is that on windows you're
somehow getting a different crash.
David Roundy

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