JVM内存问题诊断示例1

网站经常挂掉, 原因疑似Java进程被杀死。

服务器 : 阿里云ECS, CentOS 7.2
IP地址 : 192.168.1.52
CPU    : 4核-虚拟CPU Intel Xeon E5-2650 2.60GHz
物理内存: 8GB

sudo cat /var/log/messages | grep killer -A 2 -B 2

$ sudo cat /var/log/messages | grep killer -A 2 -B 2
May 21 09:55:01 ynjcws1 systemd: Started Session 500687 of user root.
May 21 09:55:02 ynjcws1 systemd: Starting Session 500687 of user root.
May 21 09:55:23 ynjcws1 kernel: java invoked oom-killer: gfp_mask=0x201da, order=0, oom_score_adj=0
May 21 09:55:24 ynjcws1 kernel: java cpuset=/ mems_allowed=0
May 21 09:55:24 ynjcws1 kernel: CPU: 3 PID: 25434 Comm: java Not tainted 3.10.0-514.6.2.el7.x86_64 #1
--
May 21 12:05:01 ynjcws1 systemd: Started Session 500843 of user root.
May 21 12:05:01 ynjcws1 systemd: Starting Session 500843 of user root.
May 21 12:05:22 ynjcws1 kernel: jstatd invoked oom-killer: gfp_mask=0x201da, order=0, oom_score_adj=0
May 21 12:05:22 ynjcws1 kernel: jstatd cpuset=/ mems_allowed=0
May 21 12:05:23 ynjcws1 kernel: CPU: 2 PID: 10467 Comm: jstatd Not tainted 3.10.0-514.6.2.el7.x86_64 #1

ifconfig

cat /proc/cpuinfo

free -h

top -o %MEM

cat /proc/meminfo | grep MemAvailable

sudo jps -v

whereis javac
whereis jstatd

sudo rz -y

sudo mkdir -p /etc/java
cd /etc/java/

# jstatd必须指定安全策略
$ cat jstatd.all.policy 

grant codebase "file:${java.home}/../lib/tools.jar" { 
   permission java.security.AllPermission; 
};

# 启动脚本
$ cat startjstatd.sh

/usr/local/jdk1.8.0_74/bin/jstatd -p 11099 -J-Djava.security.policy=/etc/java/jstatd.all.policy &

# 修改权限
$ sudo chmod 744 startjstatd.sh

sudo ./startjstatd.sh

$ sudo netstat -ntlp | grep jstatd

tcp        0      0 0.0.0.0:42582           0.0.0.0:*               LISTEN      10379/jstatd
tcp        0      0 0.0.0.0:11099           0.0.0.0:*               LISTEN      10379/jstatd

export JAVA_OPTS="$JAVA_OPTS 
	-Dcom.sun.management.jmxremote.port=19999
	-Dcom.sun.management.jmxremote.ssl=false
	-Dcom.sun.management.jmxremote.authenticate=false
	-Djava.rmi.server.hostname=192.168.1.52"