How to use the gc module for garbage collection in Python 2.x

How to use the gc module for garbage collection in Python 2.x

Introduction:
When programming in Python, we usually do not need to manually manage memory because there is a memory management mechanism in Python, that is Garbage Collection. The Garbage Collector will automatically detect and reclaim memory space that is no longer in use, thereby avoiding memory leaks and memory overflow problems. In Python 2.x version, we can control and influence the garbage collection process through the gc module. This article will introduce how to use the gc module for garbage collection in Python 2.x.

1. gc module introduction:
   The gc module (Garbage Collector module) is a garbage collection module in Python. It provides a series of functions and classes for managing and controlling the garbage collection process. The main function of the gc module is to track and mark memory objects that are no longer needed and recycle them for subsequent use.
2. Garbage collection process:
   When an object is no longer referenced in memory, the garbage collector will mark the object as a garbage object and add it to the garbage collection list. When there is insufficient memory space, the garbage collector will trigger the garbage collection process, clean up the garbage objects in the linked list and release the memory space occupied by them. The garbage collection process is divided into two stages, namely marking (Mark) and cleaning (Sweep).
3. Examples of commonly used gc module functions:
   The following are examples of some commonly used gc module functions:

(1) Enable or disable garbage collection:
gc.enable () # Enable garbage collection
gc.disable() # Disable garbage collection

(2) Manually trigger garbage collection:
gc.collect() # Manually trigger garbage collection

(3) Set the threshold for garbage collection:
gc.get_threshold() # Get the current threshold for garbage collection
gc.set_threshold(threshold) # Set the threshold for garbage collection

(4) Judgment Whether an object is reachable:
gc.is_tracked(obj) # Determine whether an object is reachable

(5) Get or set the reference count of an object:
gc.get_referents(obj) # Get the reference count of an object
gc.set_referents(obj, referents) # Set the reference count of an object

4. Sample code:
   The following is a simple sample code that demonstrates How to use gc module for garbage collection:

import gc

def create_objects():
    obj1 = object()
    obj2 = object()
    obj1.ref = obj2
    obj2.ref = obj1

def collect_garbage():
    gc.collect()

def main():
    create_objects()
    collect_garbage()

if __name__ == "__main__":
    main()

In the above code, we have created two objects obj1 and obj2 and reference each other. When calling the collect_garbage function, we manually trigger the garbage collection process. Since a circular reference is formed between obj1 and obj2, these objects will be marked as garbage objects and cleaned up by the garbage collector.

Summary:
This article introduces the method of using the gc module for garbage collection in Python 2.x, including an introduction to the gc module, the garbage collection process and examples of commonly used functions. By rationally using the gc module, we can better control and manage memory and avoid memory leaks and memory overflow problems. In actual programming, we can choose to enable or disable garbage collection as needed, manually trigger garbage collection, set the threshold for garbage collection, determine and obtain the reference count of objects, and other operations to improve code performance and memory utilization.

The above is the detailed content of How to use the gc module for garbage collection in Python 2.x. For more information, please follow other related articles on the PHP Chinese website!