# memorytop requires Python 3.4

#

# Usage: set PYTHONTRACEMALLOC=n in the environment of the hg invocation,

# where n>= is the number of frames to show in the backtrace. Put calls to

# memorytop in strategic places to show the current memory use by allocation

# site.

import gc

import tracemalloc

def memorytop(limit=10):

    gc.collect()

    snapshot = tracemalloc.take_snapshot()

    snapshot = snapshot.filter_traces(

        (

            tracemalloc.Filter(False, "<frozen importlib._bootstrap>"),

            tracemalloc.Filter(False, "<frozen importlib._bootstrap_external>"),

            tracemalloc.Filter(False, "<unknown>"),

        )

    )

    stats = snapshot.statistics('traceback')

    total = sum(stat.size for stat in stats)

    print("\nTotal allocated size: %.1f KiB\n" % (total / 1024))

    print("Lines with the biggest net allocations")

    for index, stat in enumerate(stats[:limit], 1):

        print(

            "#%d: %d objects using %.1f KiB"

            % (index, stat.count, stat.size / 1024)

        )

        for line in stat.traceback.format(most_recent_first=True):

            print('    ', line)

    other = stats[limit:]

    if other:

        size = sum(stat.size for stat in other)

        count = sum(stat.count for stat in other)

        print(

            "%s other: %d objects using %.1f KiB"

            % (len(other), count, size / 1024)

        )

    print()