#2153: r.viewshed fails on large raster: mktemp provides only 26 unique file names
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Reporter: wenzeslaus | Owner: grass-dev@…
Type: defect | Status: new
Priority: normal | Milestone: 7.0.0
Component: LibRaster | Version: svn-trunk
Keywords: r.viewshed, mktemp | Platform: MSWindows 7
Cpu: Unspecified |
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Citing original report from mailing list [http://lists.osgeo.org/pipermail
/grass-dev/2013-December/066718.html r.viewshed fails on large raster:
temp file already exists] ([http://osgeo-org.1560.x6.nabble.com/r
-viewshed-fails-on-large-raster-temp-file-already-exists-td5095763.html
nabble]):
> I was running r.viewshed in GRASS 7.0 under Win7 on a large raster with
11000 rows by 11000 columns. The algorithm ran in external memory mode
with temporary files being written to a local directory (on C:). On
starting sweeping, two temporary files were created, “STREAM_a06524” and
“STREAM_b06524”, of which the first never increased in size beyond 0 KB,
and the second grew to about 11 GB during sweeping. When sorting events,
additional temp files were created, each of about 255 MB size, which were
all named in the same logic, i.e. “STREAM_c06524”, “STREAM_d06524” etc,
with only the letter after the underscore in the file name changing to the
next letter in the alphabet. This continued until the file
“STREAM_z06524” had been created, then the algorithm crashed with “File
exists” (see sh output below). Obviously it had tried to create a file
that already existed, probably named “STREAM_a06524”. It seems that either
the programmer never counted on more files being necessary than the
alphabet has letters, or maybe something gets mixed up in the loop and the
code assumes that “STREAM_a06524” does not exist because it never wrote
any data to it.
{{{
_mktemp can create a maximum of 26 unique file names for any given
combination of base and template values. Therefore, FNZ12345 is the
last unique file name _mktemp can create for the base and template
values used in this example.
}}}
Because it [http://lists.osgeo.org/pipermail/grass-
dev/2013-December/066729.html works] on Linux, the problem is probably
connected only to MS Windows' `_mktemp` function.
"This file is part of the GNU Fortran runtime library (libgfortran).
Libgfortran is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
...
"
#2153: r.viewshed fails on large raster: mktemp provides only 26 unique file names
--------------------------------------------+-------------------------------
Reporter: wenzeslaus | Owner: grass-dev@…
Type: defect | Status: new
Priority: normal | Milestone: 7.0.0
Component: LibRaster | Version: svn-trunk
Keywords: r.viewshed, mktemp, g.tempfile | Platform: MSWindows 7
Cpu: Unspecified |
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Comment(by neteler):
Replying to [comment:3 neteler]:
> r58740 to be discussed and potentially used here
G_mkstemp() is now activated in libiostream (used by r.terraflow,
r.viewshed) in r58887. Please test in the winGRASS binaries which will be
generated in approx. 9 hours from now.
Replying to [comment:4 neteler]:
> Replying to [comment:3 neteler]:
> > r58740 to be discussed and potentially used here
>
> G_mkstemp() is now activated in libiostream (used by r.terraflow,
> r.viewshed) in r58887. Please test in the winGRASS binaries which will
be
> generated in approx. 9 hours from now.
>
> (Ticket #1902 not yet addressed)