笺注：这是在 CentOS8_Yum安装MySQL8.0 的基础上进行的。
Jemalloc是内存分配器，可以提升MySQL/MariaDB的性能。
查看MySQL的版本：
[root@redhat8 ~]# mysql -V
mysql Ver 8.0.26 for Linux on x86_64 (MySQL Community Server - GPL)
先安装软件依赖包：
[root@redhat8 ~]# yum -y install bzip2 gcc-c++ make lsof
jemalloc-5.2.1.tar.bz2的下载链接：https://pan.baidu.com/s/1S1cdmL8yfBblEj6yY-Hssg
提取码：ghb9
安装Jemalloc：
[root@redhat8 ~]# tar -jxf jemalloc-5.2.1.tar.bz2
[root@redhat8 ~]# cd jemalloc-5.2.1
[root@redhat8 jemalloc-5.2.1]# ./configure
[root@redhat8 jemalloc-5.2.1]# make && make install
[root@redhat8 jemalloc-5.2.1]# ldconfig
[root@redhat8 jemalloc-5.2.1]# ln -sf /usr/local/lib/libjemalloc* /usr/lib/
查找MySQL的环境文件：
[root@redhat8 ~]# cat /usr/lib/systemd/system/mysqld.service |grep -A1 "malloc"
# Use this to switch malloc implementation
EnvironmentFile=-/etc/sysconfig/mysql
[root@redhat8 ~]# vi /etc/sysconfig/mysql
写入：
LD_PRELOAD=/usr/lib/libjemalloc.so
保存文件退出后，重启MySQL：
[root@redhat8 ~]# systemctl restart mysqld
验证MySQL是否使用了Jemalloc：
[root@redhat8 ~]# lsof -n |grep jemalloc
mysqld 1087 mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1379 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1382 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1383 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1385 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1386 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1387 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1388 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1389 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1391 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1392 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1393 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1400 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1401 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1402 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1403 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1404 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1447 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1449 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1452 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1498 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1499 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1500 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1501 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1502 xpl_worke mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1503 xpl_worke mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1504 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1508 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1509 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1510 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1511 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1512 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1513 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1514 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1515 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1516 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1517 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
mysqld 1087 1518 mysqld mysql mem REG 253,0 6123808 202124088 /usr/local/lib/libjemalloc.so.2
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