[GRASS-dev] r.contour - G_malloc:out of memory

[Henning Lorenz]

Hi!

In Grass 6.3 on Mac OSX 10.5 I try to contour the following raster  
file (from r.info):

Type of Map:  raster               Number of Categories: 255
Data Type:    CELL
Rows:         38002
Columns:      50276
Total Cells:  1910588552
Projection: UTM (zone 40)
N: 7949005.04157202    S:    7816000   Res: 3.49994847
E:     523000    W: 347033.98326284   Res: 3.50000033
Range of data:    min = 0  max = 255

with the region set to the raster file (from g.region -p):

GRASS 6.3.0 (NovZem(old)):~ > g.region -p
projection: 1 (UTM)
zone:       40
datum:      wgs84
ellipsoid:  wgs84
north:      7949005.04157202
south:      7816000
west:       347033.98326284
east:       523000
nsres:      3.49994847
ewres:      3.50000033
rows:       38002
cols:       50276
cells:      1910588552

The file size on disk is 1.22 GB. I have 8 GB RAM, whereof 5929 MB  
free when I execute r.contour on the command line. r.contour fails  
with the following message after reading in ca. 25% of the data  
(reproduceable):

GRASS 6.3.0 (NovZem(old)):~ > r.contour --overwrite  
input=NovZem_S_highrres_red at enhanced output=NovZem_shoreline levels=1
Reading data:
r.contour(13162) malloc: *** mmap(size=405504) failed (error code=12)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug
ERROR: G_malloc: out of memory

This happens while 3020 MB memory are still free! On the other hand it  
means that r.contour used ca. 3 GB of memory for load ca. 300 MB of  
data from the disk, i.e. the whole 1.22 GB dataset would require ca.  
12 GB of free memory.

Is this behaviour expected?

Best wishes,

Henning


-- 
Henning Lorenz
Research scientist (Arctic tectonics)
The Swedish Deep Drilling Program (http://www.sddp.se; Scientific  
coordinator)

Uppsala University
Department of Earth Sciences
Villavägen 16
752 36 Uppsala
Sweden
phone:  +46 (0)18 471 23 24
mobile: +46 (0)733 622 655
fax:        +46 (0)18 50 11 10
e-mail: henning.lorenz at geo.uu.se
http://www.geofys.uu.se/?q=view/home/63

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