连接到远程数据库脚本后不退出

Question

我连接到远程数据库。我正在为此使用 sshtunnel。我可以毫无问题地连接到数据库并访问数据。

我的问题是，我的脚本在完成所有操作后都没有退出。我创建连接、下载数据、打印数据、停止 ssh 连接、打印 'exit'。该脚本在行 server.stop() 处停止工作并且不打印 'stop'。我需要中断它来停止运行这段代码。

这是代码：

from sshtunnel import SSHTunnelForwarder
from sqlalchemy import create_engine
import pandas as pd


server = SSHTunnelForwarder(
    ('host', 22),
    ssh_password='password',
    ssh_username='username',
    remote_bind_address=('127.0.0.1', 3306)
)
server.start()

engine = create_engine(
    'mysql+mysqldb://db_user:db_pass@127.0.0.1:{}/temps'.format(server.local_bind_port))

query = 'SELECT * FROM temp'

df = pd.read_sql(query, engine)
print(df.head())
print(df.tail())

server.stop()
print('stop')

此脚本不打印 'stop'。

问题：为什么这段代码不能停止工作？

编辑：

我加了

trace_logger = create_logger(loglevel="TRACE")

在此之后我注意到一些有趣的事情。带有数据传输的代码没有包含一行：Transport is closed。我在没有发送 sql 查询的情况下检查了我的代码，脚本已正确完成。

带数据传输的日志

2018-10-07 18:41:43,274| WAR | MainThrea/0967@sshtunnel | Could not read SSH configuration file: ~/.ssh/config
2018-10-07 18:41:43,275| INF | MainThrea/0993@sshtunnel | 0 keys loaded from agent
2018-10-07 18:41:43,275| INF | MainThrea/1042@sshtunnel | 0 keys loaded from host directory
2018-10-07 18:41:43,275| INF | MainThrea/0914@sshtunnel | Connecting to gateway: 192.168.0.102:22 as user ‘xxx’
2018-10-07 18:41:43,275| DEB | MainThrea/0917@sshtunnel | Concurrent connections allowed: True
2018-10-07 18:41:43,275| DEB | MainThrea/1369@sshtunnel | Trying to log in with password: xxx
2018-10-07 18:41:43,600| INF | Srv-56620/1389@sshtunnel | Opening tunnel: 0.0.0.0:56620 <> 127.0.0.1:3306
….. # data transfer
2018-10-07 18:41:43,945| INF | MainThrea/1328@sshtunnel | Closing all open connections...
<Logger sshtunnel.SSHTunnelForwarder (TRACE)>
2018-10-07 18:41:43,945| DEB | MainThrea/1332@sshtunnel | Listening tunnels: 0.0.0.0:56620
2018-10-07 18:41:43,945| INF | MainThrea/1408@sshtunnel | Shutting down tunnel ('0.0.0.0', 56620)
2018-10-07 18:41:44,048| INF | Srv-56620/1395@sshtunnel | Tunnel: 0.0.0.0:56620 <> 127.0.0.1:3306 released

没有数据传输的日志

2018-10-07 18:37:54,016| WAR | MainThrea/0967@sshtunnel | Could not read SSH configuration file: ~/.ssh/config
2018-10-07 18:37:54,017| INF | MainThrea/0993@sshtunnel | 0 keys loaded from agent
2018-10-07 18:37:54,017| INF | MainThrea/1042@sshtunnel | 0 keys loaded from host directory
2018-10-07 18:37:54,017| INF | MainThrea/0914@sshtunnel | Connecting to gateway: 192.168.0.102:22 as user ‘xxx'
2018-10-07 18:37:54,017| DEB | MainThrea/0917@sshtunnel | Concurrent connections allowed: True
2018-10-07 18:37:54,017| DEB | MainThrea/1369@sshtunnel | Trying to log in with password: xxx
2018-10-07 18:37:54,342| INF | Srv-56560/1389@sshtunnel | Opening tunnel: 0.0.0.0:56560 <> 127.0.0.1:3306
2018-10-07 18:37:54,363| INF | MainThrea/1328@sshtunnel | Closing all open connections...
<Logger sshtunnel.SSHTunnelForwarder (TRACE)>
2018-10-07 18:37:54,363| DEB | MainThrea/1332@sshtunnel | Listening tunnels: 0.0.0.0:56560
2018-10-07 18:37:54,363| INF | MainThrea/1408@sshtunnel | Shutting down tunnel ('0.0.0.0', 56560)
2018-10-07 18:37:54,448| INF | Srv-56560/1395@sshtunnel | Tunnel: 0.0.0.0:56560 <> 127.0.0.1:3306 released
2018-10-07 18:37:54,448| DEB | MainThrea/1422@sshtunnel | Transport is closed

Answer 1

日志检查后发现 sqlalchemy 个打开的连接是问题所在。

我们创建了 trace_logger = sshtunnel.create_logger(loglevel="TRACE") 并将其传递给 SSHTunnelForwarder

任何人供将来参考：

在 df.read_sql 之后添加 engine.dispose() 将关闭所有挂起的数据库连接，从而关闭 ssh 隧道。

Relevant documentation from sqlalchemy

Answer 2

只是想补充一下，以防有人遇到 engine.dispose() 不起作用的相同问题。我在 windows python 3.7。我花了几个小时才找到解决方案

在 server.start() 之前发布 server.daemon_forward_servers = True 为我解决了这个问题。

这里有更多参考资料： https://github.com/pahaz/sshtunnel/issues/138

连接到远程数据库脚本后不退出

after connect to remote database script doesn't exit

ssh-tunnel

python-3.x

pandas

编辑：

带数据传输的日志

没有数据传输的日志