[GRASS-dev] GRASS on cluster: G_malloc: out of memory management

[Glynn Clements]

Markus Neteler wrote:

> I am running GRASS on an external cluster and have to specify in the
> job scheduler how much memory I need. Despite a large amount
> defined, I always get:
> 
> v.vol.rst ...
> WARNING: Points are more dense than specified 'DMIN'--ignored 49295 points
>          (remain 9976)
> Percent complete: ERROR: G_malloc: out of memory
> 
> Is there a way to make this message more descriptive? Then I could
> try to figure out if my memory request was simply ignored. Currently
> I am quite in the dark (since the same job runs on our FEM-CEA
> cluster with the same about of RAM but different job scheduler).
> 
> Knowing how much v.vol.rst tried to allocate would be already useful.

--- lib/gis/alloc.c	(revision 34189)
+++ lib/gis/alloc.c	(working copy)
@@ -42,7 +42,7 @@
     if (buf)
 	return buf;
 
-    G_fatal_error(_("G_malloc: out of memory"));
+    G_fatal_error(_("G_malloc: unable to allocate %lu bytes"), (unsigned long) n);
     return NULL;
 }
 
A slightly more informative option would be to report the immediate
caller e.g.:

	void *G__malloc(const char *file, int line, size_t n)
	{
	    void *buf;
	
	    if (n <= 0)
		n = 1;			/* make sure we get a valid request */
	
	    buf = malloc(n);
	    if (buf)
		return buf;
	
	    G_fatal_error(_("G_malloc: unable to allocate %lu bytes at %s:%d"),
	                  (unsigned long) n, file, line);
	    return NULL;
	}

Then in gisdefs.h:

	-void *G_malloc(size_t);
	+void *G__malloc(const char *, int, size_t);
	+#define G_malloc(n) G__malloc(__FILE__, __LINE__, (n))

Alternatively, have G_malloc() call abort() on error; this will
normally generate a coredump (if coredumps are enabled) which can be
examined with gdb to determine the complete call chain and the exact
state of the process.

However, bear in mind that abort()ing on out-of-memory is likely to
produce large coredumps; ensure that "ulimit -c" is set accordingly.

-- 
Glynn Clements <glynn at gclements.plus.com>