[igraph] memory problem(?) in largest clique finding

[Sinan Kalkan]

hello there,

i am not sure whether this is a problem really. i have an
example graph with 143 nodes and i need to find its
largest clique. the program crashes, however, with the
following output:
"Error at cliques.c:61 :cliques failed, Out of memory
Aborted"

i was hoping that a 1GB memory would be enough for such
a graph. i checked the memory usage with the "top" command
and i didn't observe any suspicious growth in memory usage
(it was fixed at 0.4 percent all the time till the abort). so, probably
this is not a memory leak problem.

i looked at the code src/cliques.c:57-61 and observed that the
program tried to realloc a memory storage with the following line:
*new_member_storage=Realloc(*new_member_storage,
                              size*old_clique_count*(old_clique_count-1)/2,
                              igraph_real_t);
size, and old_clique_count are roughly the same. assuming that they
are the maximum, i.e., 143, the reallocation requests a maximum
of 143*143*143/2 * 8 (igraph_real_t is 8 bytes on my machine) which
makes 11696828 bytes ~ 10MB.
so, if i am not mistaken, the reallocation should succeed for 10MB.

can anyone suggest what the problem is, or whether i am missing a point,
or how i can get around the problem?

thank you in advance,
best regards

ps: at the time of running the program, there is a roughly 1GB of free memory
(including the swap space) and there is no other process running
that demands extensive memory.