Linux
Mysql在重啟時監聽錯誤的埠
我正在開發一個“本地”PHP 項目。這是一個在 Debian VM 中執行的 PHP 應用程序，旨在在使用者自己的 PC 上使用。
我有幾個 python 腳本作為 /etc/init.d 的根服務執行，它們處理應用程序更新、日誌、與 USB 外圍設備的通信和其他內容。
編輯 1： VM 是交鑰匙 Linux LAMP 映像，python 版本是 2.7.3，MySQL 5.5.47
PHP 應用程序通過 TCP 套接字與 python 服務對話，發送使用者需要的特定任務的請求。
現在，我試圖讓使用者選擇讓 MySQL 伺服器只綁定到 localhost 或與網路上的其他使用者共享。為此，我讓 python 服務遍歷 my.cnf 文件，並註釋掉 bind-address = 127.0.0.1 行，或者取消註釋以使伺服器再次本地化。
在 my.cnf 編輯後，python 腳本呼叫 /etc/init.d/mysql restart 使更改生效。
問題是，現在 mysql 最終偵聽了 python 服務正在偵聽 PHP 請求的埠，如果我需要重新啟動服務 Python 失敗，聲稱它無法打開該埠，因為它已經在使用中。
我不明白為什麼mysql最終會監聽python服務正在使用的埠，而不是my.cnf文件所說的3306。
此外，如果我 ssh 到 VM 並手動重新啟動 mysql，它會返回到監聽 3306，我可以啟動 python 服務。
python端的一些程式碼：
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'])樣本輸出：
$> 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)**編輯 2：**添加了 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/
這與 mysql 關係不大，而與 python 關係更大。
當你啟動一個程序時，它會從創建它的程序中繼承很多資訊，包括它的文件描述符。您的發現是 mysql 繼承了您的程序在生成時創建的偵聽套接字。
要解決此問題，您需要將 python 程式碼更改為不使用
subprocess.check_output(...)，而是使用subprocess.Popen(..., close_fds=True)或者，在您的套接字上設置 CLOEXEC 標誌將完全阻止它被繼承——儘管您需要測試此行為在您的所有程式碼路徑中是否有效，並且不會因此而發生任何奇怪的事情。以下是這樣做的基礎。
from fcntl import fcntl, FD_CLOEXEC, F_GETFD, F_SETFD flags = fcntl(socketfd, F_GETFD) flags |= FD_CLOEXEC fcntl(socketfd, F_SETFD, flags)兩者都可以解決您遇到的偵聽套接字問題。