"""

Messing around with garbage collection with circular references

and the gc and sys modules. Sys provides getrefcount()

"""

import gc

import sys

def main():

a = 4

b = 5

c_list = []

c_list.append(123)

c_list.append(456)

# reference cycle

c_list.append(c_list)

c_list[2].append(789)

# foo = ['hi']

# c_list = foo

print(c_list)

print("Stats: {}".format(gc.get_stats()))

print("Count: {}".format(gc.get_count()))

print("GC enabled: {}".format(gc.isenabled()))

print("Threshold: {}".format(gc.get_threshold()))

print("c_list is tracked: {}".format(gc.is_tracked(c_list)))

"""

The count returned is generally one higher than you might expect,

because it includes the (temporary) reference as an argument to getrefcount().

"""

print("Reference count for c_list: {}".format(sys.getrefcount(c_list)))

del c_list[2]

print("Reference count for c_list: {}".format(sys.getrefcount(c_list)))

print("Collecting: {}".format(gc.collect()))

print("Done.")

if __name__ == "__main__":

main()