Re: Producing memory traces of C storage allocation?

Corndog <ratatat@army.net> wrote:
> Hmm..this is quite the question Im sure, but does anyone know of a C
> compiler or is anyone able to tell me how to create one (roars of
> laughter) that is able to force the program being generated to log all
> calls to memory allocation routines like malloc and free in order for
> me to be able to determine the size of the heap at any point during
> the program execution? Or is there another simpler more intelligent
> way of doing it? Just writing wrappers for them doesnt work (I think)
> cos I wont intercept such calls by library routines.


This depends on the setup of the library routines and the linker.
I've worked with a compiler that has a debug version of malloc/free; all
inter-library calls to malloc/free will use these.
As for the intra-library calls: the debug library already uses the debug
versions of malloc/free, so no need to worry.


> I also know I can
> just write a separate program that will monitor the heap size of a
> target program, only doing it this way I cannot make any guarantees
> about the shape of the resulting graph cos I cant control the way the
> OS decides to interleave the execution of the two! Right?


You can give the monitoring thread a higher priority and let it sleep.
This is good for gathering general time-related memory statistics, but
it's difficult to relate that statistics to actions within the
application software.


You could also try a tool like BoundsChecker, which tries to trace
memory leaks. Checking tools like this can even work without explicit
debugging support compiled into the software, though I don't know how
they do this.


Regards,
Joachim

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