我正在开发一个“本地” PHP 项目。这是一个在 Debian VM 中运行的 PHP 应用程序，供用户自己的 PC 使用。
我有几个从 /etc/init.d 作为根服务运行的 python 脚本，它们处理应用程序更新、日志、与 USB 外围设备的通信以及其他内容。
编辑1：VM 是 Turnkey Linux LAMP 映像，python 版本为 2.7.3，MySQL 5.5.47
PHP 应用程序通过 TCP 套接字与 python 服务通信，发送用户需要的特定任务的请求。
现在，我尝试让用户选择让 MySQL 服务器仅绑定到本地主机或与网络上的其他用户共享。为此，我让 python 服务浏览 my.cnf 文件，并注释掉 bind-address = 127.0.0.1 行，或取消注释以使服务器再次本地化。
my.cnf 编辑后，python 脚本调用 /etc/init.d/mysql restart 以使更改生效。
问题是，现在 mysql 最终在 python 服务监听 PHP 请求的端口上监听，如果我需要重新启动服务，Python 就会失败，声称它无法打开该端口，因为它已经在使用中。
我不明白为什么 mysql 最终会监听 python 服务使用的端口而不是 my.cnf 文件所说的 3306。
另外，如果我通过 ssh 连接到 VM 并手动重新启动 mysql，它会重新监听 3306，然后我就可以启动 python 服务了。
Python 端的一些代码：
RECV_BUFFER = 4096
DAEMON_PORT = 5555
daemon_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
daemon_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
daemon_socket.bind(("localhost", DAEMON_PORT))
daemon_socket.listen(10)
//// SOCKET HANDLING, QUEUE and etc
if (data =='share:enable'):
import fileinput
import re
import subprocess
for line in fileinput.input('/etc/mysql/my.cnf', inplace = 1):
print re.sub(r'#*bind-address',"#bind-address", line),
print subprocess.check_output(['/etc/init.d/mysql','restart'])
示例输出：
$> lsof -i
...
...
python 17219 root 4u IPv4 25311 0t0 TCP localhost:5555 (LISTEN)
mysqld 20773 mysql 10u IPv4 33299 0t0 TCP localhost:mysql (LISTEN)
$> echo 'share:enable' | netcat localhost 5555
$> lsof -i
....
....
python 17219 root 4u IPv4 25311 0t0 TCP localhost:5555 (LISTEN)
mysqld_sa 17361 root 4u IPv4 25311 0t0 TCP localhost:5555 (LISTEN)
mysqld 17856 mysql 4u IPv4 25311 0t0 TCP localhost:5555 (LISTEN)
mysqld 17856 mysql 13u IPv4 25782 0t0 TCP localhost:mysql (LISTEN)
logger 17857 root 4u IPv4 25311 0t0 TCP localhost:5555 (LISTEN)
编辑2：添加了我的 my.cnf MySQL 配置文件。
#
# The MySQL database server configuration file.
#
# You can copy this to one of:
# - "/etc/mysql/my.cnf" to set global options,
# - "~/.my.cnf" to set user-specific options.
#
# One can use all long options that the program supports.
# Run program with --help to get a list of available options and with
# --print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html
# This will be passed to all mysql clients
# It has been reported that passwords should be enclosed with ticks/quotes
# escpecially if they contain "#" chars...
# Remember to edit /etc/mysql/debian.cnf when changing the socket location.
[client]
port = 3306
socket = /var/run/mysqld/mysqld.sock
# Here is entries for some specific programs
# The following values assume you have at least 32M ram
# This was formally known as [safe_mysqld]. Both versions are currently parsed.
[mysqld_safe]
socket = /var/run/mysqld/mysqld.sock
nice = 0
[mysqld]
#
# * Basic Settings
#
user = mysql
pid-file = /var/run/mysqld/mysqld.pid
socket = /var/run/mysqld/mysqld.sock
port = 3306
basedir = /usr
datadir = /var/lib/mysql
tmpdir = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking
#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
bind-address = 127.0.0.1
#
# * Fine Tuning
#
key_buffer = 16M
max_allowed_packet = 16M
thread_stack = 192K
thread_cache_size = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover = BACKUP
#max_connections = 100
#table_cache = 64
#thread_concurrency = 10
#
# * Query Cache Configuration
#
query_cache_limit = 1M
query_cache_size = 16M
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file = /var/log/mysql/mysql.log
#general_log = 1
#
# Error logging goes to syslog due to /etc/mysql/conf.d/mysqld_safe_syslog.cnf.
#
# Here you can see queries with especially long duration
#log_slow_queries = /var/log/mysql/mysql-slow.log
#long_query_time = 2
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
# other settings you may need to change.
#server-id = 1
#log_bin = /var/log/mysql/mysql-bin.log
expire_logs_days = 10
max_binlog_size = 100M
#binlog_do_db = include_database_name
#binlog_ignore_db = include_database_name
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem
[mysqldump]
#quick quote-names
max_allowed_packet = 16M
[mysql]
#no-auto-rehash # faster start of mysql but no tab completition
[isamchk]
key_buffer = 16M
#
# * IMPORTANT: Additional settings that can override those from this file!
# The files must end with '.cnf', otherwise they'll be ignored.
#
!includedir /etc/mysql/conf.d/
答案1
这与 mysql 关系不大，与 python 关系较大。
当你启动一个进程时，它继承来自创建它的进程的大量信息，包括其文件描述符。您发现 mysql 继承了进程在生成时创建的侦听套接字。
为了解决这个问题，你需要将你的python代码改为不使用subprocess.check_output(...)，而是使用subprocess.Popen(..., close_fds=True)
或者，在套接字上设置 CLOEXEC 标志将完全阻止它被继承——尽管您需要测试此行为是否在所有代码路径中有效并且不会因此发生任何奇怪的事情。以下是执行此操作的基础。
from fcntl import fcntl, FD_CLOEXEC, F_GETFD, F_SETFD
flags = fcntl(socketfd, F_GETFD)
flags |= FD_CLOEXEC
fcntl(socketfd, F_SETFD, flags)
两者都可以解决您遇到的监听套接字问题。