Question

给出以下Python代码：

# Use impyla package to access Impala
from impala.dbapi import connect
import logging

def process():
    conn = connect(host=host, port=port)  # Mocking host and port
    try:
        cursor = conn.cursor()
        # Execute query and fetch result
    except:
        loggin.error("Task failed with some exception")
    finally:
        cursor.close()  # Exception here!
        conn.close()

创建了与Impala的连接。但由于Impala超时，cursor.close()出现了异常。

在给定潜在异常的情况下关闭cursor和conn的正确方法是什么？

Answer 1

你必须嵌套try-blocks：

def process():
    conn = connect(host=host, port=port)  # Mocking host and port
    try:
        cursor = conn.cursor()
        try:
            # Execute query and fetch result
        finally:
            # here cursor may fail
            cursor.close()
    except:
        loggin.error("Task failed with some exception")
    finally:
        conn.close()

要避免使用此类try-finally-blocks，您可以使用with - 语句：

def process():
    conn = connect(host=host, port=port)  # Mocking host and port
    try:
        with conn.cursor() as cursor:
            # Execute query and fetch result
            # cursor is automatically closed
    except:
        loggin.error("Task failed with some exception")
    finally:
        conn.close()

如何处理＆＃34;最终＆＃34;块？

1 个答案: