I am new to JavaMelody and benchmark. I am using JavaMelody to monitor my Jersey Application in tomcat following https://dzone.com/articles/a-step-by-step-guide-to-tomcat-performance-monitor.
My application setup: 4 docker containers setup by docker-compose: myapplication (tomcat, jersey application), kafka, postgres, zookeeper.
I got the following details from javaMelody monitoring page:
Host: 16a180e86bba@172.18.0.5
Java memory used: 784 Mb / 7,124 Mb ++++++++++++
Nb of http sessions: 0
Nb of active threads
(current http requests): 9
Nb of active jdbc connections: 0
Nb of used jdbc connections
(opened if no datasource): 0
System load 27.89
% System CPU 93.36 ++++++++++++
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# Details
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OS: OS Linux, 4.11.0-32-generic , amd64/64 (8 cores)
Java: OpenJDK Runtime Environment, 1.8.0
JVM: OpenJDK 64-Bit Server VM
PID of process: 1
Nb of opened files 418 / 1,048,576 ++++++++++++
Server: Server Apache Tomcat/8.0.50
Webapp context: /event-bus
Start: 2/28/18 2:47 PM
JVM arguments: -Djava.util.logging.config.file=/usr/local/tomcat/conf/logging.properties
-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
-Djdk.tls.ephemeralDHKeySize=2048
-Djava.protocol.handler.pkgs=org.apache.catalina.webresources
-Xdebug
-Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=9999
-Dignore.endorsed.dirs=
-Dcatalina.base=/usr/local/tomcat
-Dcatalina.home=/usr/local/tomcat
-Djava.io.tmpdir=/usr/local/tomcat/temp
Mean age of http sessions (min): -1
Tomcat "http-apr-8080": Busy threads = 17 / 200 ++++++++++++
Bytes received = 65,071,259
Bytes sent = 4,411,314
Request count = 538,335
Error count = 19,253
Sum of processing times (ms) = 17,998,558
Max processing time (ms) = 3,161
Memory: Non heap memory = 99 Mb (Perm Gen, Code Cache),
Buffered memory = 33 Mb,
Loaded classes = 9,535,
Garbage collection time = 1,420 ms,
Process cpu time = 854,410 ms,
Committed virtual memory = 14,718 Mb,
Free physical memory = 21,865 Mb,
Total physical memory = 32,052 Mb,
Free swap space = 32,651 Mb,
Total swap space = 32,651 Mb
Free disk space: 408,262 Mb
Dependencies: Dependencies Dependencies View Maven's pom View Maven's pom
Threads Threads
Threads on 16a180e86bba@172.18.0.5: Number = 624, Maximum = 681, Total started = 1,182
I have some questions:
1, I setup 4 docker containers and tomcat is running in one of them. Does JavaMelody give out accurate result on CPU and memory usage of my application or just docker containers?
2, There are 8 cores in my machine, does % System CPU 93.36
mean my application used 93.36% of all 8 cores CPU resource?
I used docker stats <docker id>
and got CPU %
of my application is about 336%. I am confused.
3, what does system load
mean?
4, what does 7124 Mb
mean in Java memory used: 784 Mb / 7,124 Mb ++++++++++++
?
5, In Tomcat "http-apr-8080": Busy threads = 17 / 200 ++++++++++++
and Threads on 16a180e86bba@172.18.0.5: Number = 624, Maximum = 681, Total started = 1,182
.
Does 17/200
mean the maximum number of threads to accept connections is 200, but only 17 are used. but what does Number = 624, Maximum = 681, Total started = 1,182
mean?
6, I used ab to send 20000 requests in 200 concurrency. But why only 17/200
used? How to make 200/200
?
7, from report of ab, I found 1.3% failed requests. Does this mean I setup too many concurrency in ab test? Or does this mean tomcat cannot handle all requestion (but only 17/200 used in tomcat)?
Thanks.
Theads on ...: Number = 624, Maximum = 681, Total started = 1,182
means 624 threads are live, 681 were alive at the maximum some time ago, 1182 threads were started since starting Tomcat