Example of logging memory usage before and after invoking a function in Python using decorators

log_memory_usage_example.py

# Running the script below will yield the following results:
#
# $ ipython log_memory_usage_example.py
# INFO:root:memory use before calling make_large_string : 19,340 kb
# INFO:root:memory use after calling make_large_string  : 85,840 kb
#
import functools
import logging
import resource


def log_memory_usage(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        logging.info(
            'memory use before calling {} : {:,} kb'.format(
                func.__name__,
                resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
            )
        )
        return_value = func(*args, **kwargs)
        logging.info(
            'memory use after calling {}  : {:,} kb'.format(
                func.__name__,
                resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
            )
        )
        return return_value
    return wrapper


# keep a reference to prevent garbage collection
# when calling make_large_string()
large_string = None


@log_memory_usage
def make_large_string():
    global large_string
    # use >= 64MB of memory
    large_string = "a"*1024*1024*64

logging.basicConfig(level=logging.DEBUG)
make_large_string()