How mysql/mariadb generates core files

Be careful ： open core There are two risks after configuration

1、 Disk space may be full

    ---- Because it will mysql server All memory information of is exported to core In file , Include buffer pool The content in , There may be dozens of hundreds G size

2、mysql appear crash After starting, the speed will be slow

    ---- Because you need to export a large amount of data to core In file , Therefore, the startup speed will be much slower .

# Generate core File steps

1、 open linux Of core File configuration

    ulimit -c unlimited

2、 Modify the configuration file , add to core_file To configure （ remarks ： Configure in [mysqld] below ）, And restart the database

3、 To configure  suid_dumpable（ mysql Usually with suid Mode start ）

    echo 2 >/proc/sys/fs/suid_dumpable   # Before changing, the parameter value is 0

4、 Set up core File storage directory and set full control permissions

    mkdir -p /data/core && chmod 777 /data/core && echo "/data/core/core" > /proc/sys/kernel/core_pattern  # Before the reform /proc/sys/kernel/core_pattern The value is core

# simulation mysql Of crash scene

 kill -SEGV  Database process number

# Use gdb see core file

cd /data/core

gdb mysqld core.8983

-- This article refers to mysql core Correct opening posture of files - JavaShuo