How to manage memory leaks in a long-running Python 2.7 web application?
I'm confused about I need help solving I'm running a Flask web application on Python 2.7, and I've noticed that it gradually consumes more memory over time, leading to performance degradation and eventual crashes. While monitoring memory usage using `objgraph` and `gc` modules, I found that certain objects are not being garbage collected, which suggests potential memory leaks. Here’s a simplified version of how I’m currently managing my routes: ```python from flask import Flask, jsonify app = Flask(__name__) # Simulated global variable for caching data cache = {} @app.route('/data/<key>') def get_data(key): if key in cache: return jsonify({'value': cache[key]}) # Simulate data fetching data = fetch_data_from_db(key) cache[key] = data return jsonify({'value': data}) def fetch_data_from_db(key): # Simulated database call return "Data for " + key if __name__ == '__main__': app.run() ``` I suspect the `cache` dictionary might be holding onto references longer than necessary, especially if it keeps growing with unique keys. I've tried manually clearing the cache with `cache.clear()` after a certain period, but it hasn't solved the issue. I also attempted using weak references with `collections.OrderedDict` as a limited cache, but I ran into issues where expired keys weren’t being properly removed: ```python from collections import OrderedDict import weakref class WeakValueDict(OrderedDict): def __setitem__(self, key, value): super(WeakValueDict, self).__setitem__(key, weakref.ref(value)) def __getitem__(self, key): ref = super(WeakValueDict, self).__getitem__(key) if ref() is None: del self[key] raise KeyError(key) return ref() ``` But this approach led to a `TypeError: 'NoneType' object is not callable` when trying to access the cached values, indicating that the weak reference might have been collected prematurely. I’m unsure how to effectively manage the cache's lifetime without introducing significant overhead or complexity. Any insights into best practices for memory management in a long-running Python 2.7 application would be greatly appreciated! This is part of a larger web app I'm building. Thanks in advance! Could this be a known issue? Hoping someone can shed some light on this.