[petsc-dev] SuperLU link error on BGP FEN

[Jed Brown]

On Thu, Dec 2, 2010 at 23:19, Matthew Knepley <knepley at gmail.com> wrote:

> How exactly does that happen? I have just checked that I ran multiple
> configures and did not clobber those logs.
>

When a new configure process starts, it truncates the file.  You only
relocate it later.  It's a race condition, so may not happen every time, or
you might not have correct contents in each of your files.


> I do not think this works on NTFS.
>

NTFS is lame and does not have a way to atomic rename when the destination
file exists.  But it does have both hardlinks and symlinks.  In the proposed
model $PETSC_DIR/configure.log is only a convenience for the user, it is not
being read or written concurrently, so the fact that redirecting the symlink
cannot be done atomically should not be a problem (racing a human is safer
than racing another process).

Jed
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