Teach you how to monitor Tomcat's JVM memory through JConsoler

1. How to monitor Tomcat
2. Java's own monitoring commands
3. Tomcat troubleshooting case
4. Configure Tomcat JMX monitoring
5. Use Jsconsole to connect to JMX to view monitoring data

Monitoring Tomcat's JVM memory through JConsoler

1. How to monitor Tomcat

Simple commands
Ready-made scripts
Custom monitoring through zabbix

Custom monitoring: anything that can be obtained by command can be monitored

Monitoring java through jmx

Other monitoring

Monitoring hardware via ipmi

Monitor network devices through snmp, as long as they support snmp

2. Java's own monitoring commands

jps exports java related processes
Format: jps -lvm
Parameter options: -lvm most detailed

[root@localhost ~]# jps -lvm
7457 org.apache.catalina.startup.Bootstrap start start -Djava.util.logging.config.file=/application/tomcat/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= -Dcatalina.base=/application/tomcat -Dcatalina.home=/application/tomcat -Djava.io.tmpdir=/application/tomcat/temp
7525 org.apache.catalina.startup.Bootstrap start start -Djava.util.logging.config.file=/application/tomcat_8082/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= -Dcatalina.base=/application/tomcat_8082 -Dcatalina.home=/application/tomcat_8082 -Djava.io.tmpdir=/application/tomcat_8082/temp
9144 sun.tools.jps.Jps -lvm -Denv.class.path=.:/application/jdk/lib:/application/jdk/jre/lib:/application/jdk/lib/tools.jar -Dapplication.home=/application/jdk1.8.0_60 -Xms8m
7482 org.apache.catalina.startup.Bootstrap start start -Djava.util.logging.config.file=/application/tomcat_8081/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= -Dcatalina.base=/application/tomcat_8081 -Dcatalina.home=/application/tomcat_8081 -Djava.io.tmpdir=/application/tomcat_8081/temp

jmap exports jvm information, often used for custom monitoring
Format: jmap pid
Parameter: -heap

[root@localhost ~]# jmap -heap 7457
Attaching to process ID 7457, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.60-b23

using thread-local object allocation.
Mark Sweep Compact GC

Heap Configuration:
   MinHeapFreeRatio = 40
   MaxHeapFreeRatio = 70
   MaxHeapSize = 255852544 (244.0MB)
   NewSize = 5570560 (5.3125MB)
   MaxNewSize = 85262336 (81.3125MB)
   OldSize = 11206656 (10.6875MB)
   NewRatio = 2
   SurvivorRatio = 8
   MetaspaceSize = 21807104 (20.796875MB)
   CompressedClassSpaceSize = 1073741824 (1024.0MB)
   MaxMetaspaceSize = 17592186044415 MB
   G1HeapRegionSize = 0 (0.0MB)

Heap Usage: #For monitoring, pay attention to this column New Generation (Eden + 1 Survivor Space):
   capacity = 12779520 (12.1875MB)
   used = 11689352 (11.147834777832031MB)
   free = 1090168 (1.0396652221679688MB)
   91.46941356169872% used
Eden Space: #For monitoring, please pay attention to this column capacity = 11403264 (10.875MB)
   used = 11059616 (10.547271728515625MB)
   free = 343648 (0.327728271484375MB)
   96.98640669899426% used
From Space: #For monitoring, please pay attention to this column capacity = 1376256 (1.3125MB)
   used = 629736 (0.6005630493164062MB)
   free = 746520 (0.7119369506835938MB)
   45.75718470982143% used
To Space: #For monitoring, please pay attention to this column capacity = 1376256 (1.3125MB)
   used = 0 (0.0MB)
   free = 1376256 (1.3125MB)
   0.0% used
tenured generation: #For monitoring, please pay attention to this column capacity = 28164096 (26.859375MB)
   used = 18313224 (17.46485137939453MB)
   free = 9850872 (9.394523620605469MB)
   65.02329774760035% used

21146 interned Strings occupying 1882520 bytes.

jstatck exports Java process information, which is often used for Java program failures. It is necessary to export thread information for research with developers.
Format: jstack -l pid

[root@localhost ~]# jstack -l 7457

3. Tomcat troubleshooting case

The system load is high and Tomcat occupies a high CPU

1. jps/top/htop accurately determine which java process caused
2.jstack exports java threads
3.catalina.out log analysis
4.jmap exports jvm information, which can be analyzed by mat tool

4. Configure Tomcat JMX monitoring

Custom monitoring: Write the script directly on the tomcat server and in the zabbix configuration file
First, you need to install zabbix-java-gateway on the zabiix server and then enable the monitoring function on the tomcat server.
tomcat enables jmx monitoring function

#Modify bin/catalina.sh
[root@localhost tomcat]# vim bin/catalina.sh
#Note that you cannot write it in separate lines, otherwise you will get an error message saying that the command cannot be found. Write it on one line CATALINA_OPTS="$CATALINA_OPTS"
-Dcom.sun.management.jmxremote
-Dcom.sun.management.jmxremote.port=12345
-Dcom.sun.management.jmxremote.authenticate=false
-Dcom.sun.management.jxmremote.ssl=false
-Djava.rmi.server.hostname="192.168.81.210"
#Correct way to write CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=12345 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jxmremote.ssl=false -Djava.rmi.server.hostname=192.168.81.210"


#DescriptionCATALINA_OPTS="$CATALINA_OPTS" #Modify the tomcat startup parameters -Dcom.sun.management.jmxremote #Enable the tomcat remote management function -Dcom.sun.management.jmxremote.port=12345 #In addition to port 12345, the remote management function will also generate 2 random ports. We can open all ports Dcom.sun.management.jmxremote.authenticat=false #Is authentication required during monitoring? -Dcom.sun.management.jmxremote.ssl=false #Is SSL connection enabled? -Djava.rmi.server.hostname="192.168.81.210" #Set the ip of the server where tomcat is located

After the configuration is complete, restart tomcat and you can use the ps command to see that the output information has a few more lines we wrote [root@localhost tomcat]# ps aux | grep java
root 17786 5.7 10.6 2306592 105860 pts/1 Sl 15:52 0:08 /application/jdk/bin/java
-Djava.util.logging.config.file=/application/tomcat/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
-Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=12345
-Dcom.sun.management.jmxremote.authenticate=false 
-Dcom.sun.management.jxmremote.ssl=false 
-Djava.rmi.server.hostname=192.168.81.210 
-Dignore.endorsed.dirs= 
-classpath /application/tomcat/bin/bootstrap.jar:/application/tomcat/bin/tomcat-juli.jar 
-Dcatalina.base=/application/tomcat 
-Dcatalina.home=/application/tomcat 
-Djava.io.tmpdir=/application/tomcat/temp org.apache.catalina.startup.Bootstrap start

Use the ss/netstat command to see the three additional ports [root@localhost tomcat]# ss -lnptu | grep java
tcp LISTEN 0 100 :::8080 :::* users:(("java",pid=17786,fd=56))
#Our set tcp LISTEN 0 50 :::12345 :::* users:(("java",pid=17786,fd=22))
#Random 1
tcp LISTEN 0 50 :::46272 :::* users:(("java",pid=17786,fd=21))
# Random 2
tcp LISTEN 0 50 :::46081 :::* users:(("java",pid=17786,fd=24))
tcp LISTEN 0 1 ::ffff:127.0.0.1:8005 :::* users:(("java",pid=17786,fd=65))

5. Use Jsconsole to connect to JMX to view monitoring data

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