[GRASS-user] memory requirement of v.net.allpairs module

Pankaj Kr Sharma pkscwc at gmail.com
Sun Dec 25 11:04:36 EST 2011

Dear Developers and users,

On a small test region (11000x11000 cells), with a threshold of 1000sqkm,
r.stream.extract resulted in a stream vector network of 190 points and
lines. The v.net.allpairs generated a table of distances between each point
within 10 seconds on my home machine (only 4gb ram).  I thought that I got
my solution for finding sub-basins of a very large area. (Please refer to
my earlier posts in this regard.)

On my work setup, (better machine, 16gb RAM , six cores), I followed this
1. r.grow by one cell  on area of interest. (It's an important step. Thanks
to Markus Metz for this tip.) Time taken by the module: approximately 2

2. r.stream.extract on my area of interest.(42000*42000 cells) with 100
sq.km. as threshold (12345 in number of cells.)
    Please note that the r.stream.extract module's vector output was a
network of 1,45,000 (approx) points and lines.
Time taken by module: approximately 24 hours.

3. Then I ran "v.net.allpairs" on this network. Now, v.net.allpairs is
still running. Approximately, one week has elapsed.
After three days, a message appeared on the console that says "writing data
into the table". After four days of this message, the progress bar is still
without any colour. ( Which I consider as progress being less than one

The other thing which I noticed was the memory consumption. The module has
consumed 15.5 gb ram out of 16gb, thereafter it consumed 166gb of swap
space out of 500gb swap space available.( Earlier, I had kept complete one
disk of 1 tb for swap.)

Some of the answers for this response of the module, I have myself.

Like, the module has more calculations to do.
Still, as per my calculation of time required 582410*10 seconds/(24*60*60)~
6.75 days

And, I should have my postgres table ready for further calculations.
But, still there is no sign of any progress.
Is the time and memory being consumed by the module as per design and ok.

I can definitely sub-divide into basins and work further.
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