Python3 进程卡死调试方法
环境：Ubuntu（apt 包管理发行版本操作类似）、Python3.6（其余版本操作类似）
症状：线上一个 Python 进程总是莫名卡死，无日志输出。
调试步骤：
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安装基础包：
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apt update apt install gdb python-dbg
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找到当前Python 版本的 gdb.py 文件
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find / -name *gdb.py
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找到如下格式文件
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/usr/share/gdb/auto-load/usr/bin/python3.6-gdb.py
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找到需要 debug 的 Python 进程
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ps -aux | grep python
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root 147 0.0 0.5 1025752 44400 ? Sl Aug23 0:00 python3 main.py
- 进入进程
- - ```shell
gdb python3 147
# 请注意！！！ gdb 后面的解释器，必须是调试进程所使用的解释器！！！！
```
- 加载 gdb.py 文件
- - ```shell
(gdb) source /usr/share/gdb/auto-load/usr/bin/python3.6-gdb.py
```
- 查看卡在那一行代码了(可以看标记显示卡在了 **self._sock.recv_into(b) ** 调用上 )
- - ```shell
(gdb) py-list
584 self._checkReadable()
585 if self._timeout_occurred:
586 raise OSError("cannot read from timed out object")
587 while True:
588 try:
>589 return self._sock.recv_into(b)
590 except timeout:
591 self._timeout_occurred = True
592 raise
593 except error as e:
594 if e.args[0] in _blocking_errnos:
```
- 查看回溯
- - ```shell
(gdb) py-bt
Traceback (most recent call first):
File "/usr/local/python3.7.4/lib/python3.7/socket.py", line 589, in readinto
return self._sock.recv_into(b)
File "/usr/local/python3.7.4/lib/python3.7/smtplib.py", line 387, in getreply
line = self.file.readline(_MAXLINE + 1)
File "/usr/local/python3.7.4/lib/python3.7/smtplib.py", line 338, in connect
(code, msg) = self.getreply()
File "/usr/local/python3.7.4/lib/python3.7/smtplib.py", line 251, in __init__
(code, msg) = self.connect(host, port)
File "/home/work/public/mail.py", line 62, in create_connection
smtp_obj = smtplib.SMTP(self.host)
File "/home/work/public/mail.py", line 45, in send
mail_conn = self.create_connection
File "/home/work/app/xxx.py", line 416, in send_report
_subtype='HTML'
File "/home/work/app/xxx.py", line 355, in download_work
self.send_report("xxxxx")
File "/home/work/app/xxx.py", line 398, in branch
self.download_work(task)
File "/home/work/app/xxx.py", line 434, in start_work
dbs.branch(task)
File "/usr/local/python3.7.4/lib/python3.7/multiprocessing/process.py", line 99, in run
self._target(*self._args, **self._kwargs)
File "/usr/local/python3.7.4/lib/python3.7/multiprocessing/process.py", line 297, in _bootstrap
self.run()
File "/usr/local/python3.7.4/lib/python3.7/multiprocessing/popen_fork.py", line 74, in _launch
code = process_obj._bootstrap()
File "/usr/local/python3.7.4/lib/python3.7/multiprocessing/popen_fork.py", line 20, in __init__
self._launch(process_obj)
File "/usr/local/python3.7.4/lib/python3.7/multiprocessing/context.py", line 277, in _Popen
return Popen(process_obj)
File "/usr/local/python3.7.4/lib/python3.7/multiprocessing/context.py", line 223, in _Popen
return _default_context.get_context().Process._Popen(process_obj)
File "/usr/local/python3.7.4/lib/python3.7/multiprocessing/process.py", line 112, in start
self._popen = self._Popen(self)
File "main.py", line 63, in main
p.start()
File "main.py", line 83, in <module>
main()
(gdb)
```
以上完毕！！！