Calculate memory with cg-mem

[dmeneses]

I want to calculate the memory usage of my program and reproduce the a memory limit exceeded. No luck so far.

To run isolate I'm using this:

./isolate --cg -i $SANDBOX_INPUT --cg-mem=$SANDBOX_MEMORY --cg-timing -t $SANDBOX_TIME -M run-stats --run ./main

I've always get time limit but not memory limit.

To reproduce the memory limit I'm using this:

int main() {
    while(true) new int;
}

[gollux]

I want to calculate the memory usage of my program and reproduce the a memory limit exceeded. No luck so far.

This is strange. Could you please try the same without control groups? (I.e., normal "--mem" limit.)

[bblackham]

The reason for this is because the pointer is never dereferenced. The
new operation will be returning NULL when the memory limit is hit, but
nothing in the program uses the return value.

Out of memory errors are difficult to identify, because typically the
program just segfaults when it tries to dereference a NULL pointer from
malloc() or new.

[bblackham]

Additionally, there is no "out of memory" result from isolate, for pretty much this reason.

However, you should be able to see when the process terminates that the cg memory is equal to the limit, which is a pretty good indication that it ran out of memory. In at least one contest system I know of, it uses the fact that the memory usage maxed out and that the program died on a SIGSEGV to assume that it is an out of memory error. It's just a guess, but a reasonable one.

dmeneses : given this, are you happy to close the issue?

[dmeneses]

Yeap, thanks!