解決RuntimeError: maximum recursion depth exceeded遞歸異常

/ 前言 /

       不久前寫了一個腳本檢測Linux某一個服務是否是啓動狀態, 因爲服務啓動時間較長就加了一個遞歸操作, 結果報錯RuntimeError: maximum recursion depth exceeded, 我們來看下如何解決

/ 1 / 問題分析

       問題出現後我去網上查找發現報錯原因是遞歸次數超過了Python3.x的默認遞歸深度, 那麼我們來測試一下Python3.x和Python2.x的遞歸深度是多少

測試代碼

# -*- coding: UTF-8 -*-

def recursion_test (num):
	print("當前遞歸次數 : {%s}"%num)
    num += 1
    recursion_test(num)

if __name__ == '__main__':
    recursion_test(1)

Python3.7測試結果

在遞歸997次時報錯

/usr/bin/python /Users/wise/projects/one-box/python/test.py
當前遞歸次數 : {1}
...
當前遞歸次數 : {997}
Traceback (most recent call last):
  File "/Users/wise/projects/one-box/python/test.py", line 10, in <module>
    recursion_test(1)
  File "/Users/wise/projects/one-box/python/test.py", line 6, in recursion_test
    print("當前遞歸次數 : {%s}"%num)
RuntimeError: maximum recursion depth exceeded while getting the str of an object

Process finished with exit code 1

Python2.7測試結果

在遞歸999次時報錯

/usr/bin/python /Users/wise/projects/one-box/python/test.py
當前遞歸次數 : {1}
...
當前遞歸次數 : {999}
Traceback (most recent call last):
  File "/Users/wise/projects/one-box/python/test.py", line 10, in <module>
    recursion_test(1)
  File "/Users/wise/projects/one-box/python/test.py", line 6, in recursion_test
    print("當前遞歸次數 : {%s}"%num)
RuntimeError: maximum recursion depth exceeded while getting the str of an object

Process finished with exit code 1

/ 2 / 解決方法

修改Python默認遞歸次數

import sys
sys.setrecursionlimit(2000)

測試結果

當前遞歸次數 : {1}
...
當前遞歸次數 : {1998}
Traceback (most recent call last):
  File "/Users/wise/PycharmProjects/csdn/test.py", line 10, in recursion_test
  [Previous line repeated 996 more times]
  File "/Users/wise/PycharmProjects/csdn/test.py", line 8, in recursion_test
    print("當前遞歸次數 : {%s}"%num)
RecursionError: maximum recursion depth exceeded while calling a Python object