这里以tomcat为例
1 找出tomcat进程号
[root@local ~]# ps -aux | grep java
root 16708 6.8 9.8 28268812 6496460 ? Sl Dec25 72:41 /opt/software/jdk8/jdk1.8.0_201-amd64/bin/java -Djava.util.logging.config.file=/opt/software/apache-tomcat-8.5.41/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /opt/software/apache-tomcat-8.5.41/bin/bootstrap.jar:/opt/software/apache-tomcat-8.5.41/bin/tomcat-juli.jar -Dcatalina.base=/opt/software/apache-tomcat-8.5.41 -Dcatalina.home=/opt/software/apache-tomcat-8.5.41 -Djava.io.tmpdir=/opt/software/apache-tomcat-8.5.41/temp org.apache.catalina.startup.Bootstrap start
root 21104 0.0 0.0 112708 980 pts/0 S+ 10:23 0:00 grep --color=auto java
2 查看应用程序进程打开的文件数
[root@local ~]# lsof -p 16708 | wc -l
2183