Practical Python Garbage Collection and Memory Analysis: 10 Useful Code Examples

In Python, garbage collection automatically manages memory by detecting objects that are no longer in use and freeing their memory, while memory analysis tools help identify leaks and optimize usage.

1. Reference counting garbage collection:

import sys

a = [1, 2, 3]
b = a
del a
print(sys.getrefcount(b))  # 输出: 2

2. Cyclic references and mark‑sweep garbage collection:

import gc

class Node:
    def __init__(self):
        self.next = None

a = Node()
b = Node()
a.next = b
b.next = a

# 手动触发垃圾回收
gc.collect()

3. Inspect an object's reference count:

import sys

a = [1, 2, 3]
print(sys.getrefcount(a))  # 输出: 2

4. Use gc.get_objects() to view currently existing objects:

import gc

objects = gc.get_objects()
print(len(objects))  # 输出: 当前存在的对象数量

5. Use gc.get_referents() to see an object's referents:

import gc

a = [1, 2, 3]
b = a
referents = gc.get_referents(b)
print(referents)  # 输出: [1, 2, 3]

6. Use gc.get_referrers() to see an object's referrers:

import gc

a = [1, 2, 3]
b = a
referrers = gc.get_referrers(a)
print(referrers)  # 输出: [b, globals()]

7. Use tracemalloc for memory profiling:

import tracemalloc

tracemalloc.start()
# 执行一些代码
snapshot = tracemalloc.take_snapshot()
top_stats = snapshot.statistics("lineno")

for stat in top_stats[:10]:
    print(stat)

8. Use memory_profiler for line‑by‑line memory analysis:

from memory_profiler import profile

@profile
def my_function():
    # 函数代码
    pass

my_function()

9. Use pympler.muppy() to list all current objects:

from pympler import muppy, summary

all_objects = muppy.get_objects()
sum1 = summary.summarize(all_objects)

summary.print_(sum1)

10. Use objgraph to generate an object reference graph:

import objgraph

a = [1, 2, 3]
b = [4, 5, 6]
a.append(b)
b.append(a)

objgraph.show_refs([a], filename="ref_graph.png")

These examples illustrate common scenarios for Python garbage collection and memory analysis, showing how to inspect reference counts, detect cyclic references, list existing objects, and employ tools such as tracemalloc , memory_profiler , pympler , and objgraph to understand and optimize memory usage.

Hope these examples are helpful; feel free to ask further questions.