Messing around with garbage collection with circular references

jwasham · jwasham · commit f6802ef35353 · 2016-08-14T20:22:25.000-07:00
and the gc and sys modules.
diff --git a/experiments/garbage_collection.py b/experiments/garbage_collection.py
@@ -0,0 +1,46 @@
+"""
+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()
