Slides accompanying a lightning talk I gave at the Altamira Fall 2013 conference.

1. jps & jvmtop
Scott Leberknight

2. "How you monitor your
software is as important as
its functionality"
- Nathan Marz, "Your Code is Wrong"

3. jps
Like ps, but lists Java processes

4. jps

5. jps -l
(that's a lowercase L)

6. jps -m

7. jps -v

8. jps -lmv
(of course you can combine arguments...)

9. monitor remote host
jps foo.bar.com:6666
(a jstatd process must be running on remote host)

10. beware tmpwatch!
jps gets info from /tmp/hsperfdata_<username>/<pid>

11. beware tmpwatch! (2)

12. beware tmpwatch! (3)
tmpwatch could delete hsperfdata files for long
running VMs, e.g. Hadoop NameNode
jps won't see JVMs if process file deleted!
oops!

13. jps summary
list process id and class name
options:
-q: suppress class name
-l: fully-qualified class name
-m: arguments to main()
-v: VM arguments
-V: VM arguments via flag file

14. jvmtop
Like top, but for Java processes

15. ./jvmtop.sh

16. jvmtop columns
PID: process id
MAIN-CLASS: "jvm name"; class with main() method
HPCUR: currently used heap memory
HPMAX: maximum heap memory used
NHCUR: current non-heap memory used (e.g. PermGen)
NHMAX: maximum non-heap memory JVM can allocate

17. jvmtop columns (2)
CPU: the CPU utilization
GC: % of time spent in garbage collection
VM: information about the JVM (S6U31 = Sun 6, update 31)
USERNAME: process owner
#T: number of JVM threads
DL: deadlock indicator (shows !D if deadlock detected)

18. ./jvmtop.sh <pid>

19. jvmtop detail columns
TID: thread id
NAME: thread name
STATE: thread state
CPU: the CPU utilization (relative to all processors)
TOTALCPU: CPU utilization since thread started
BLOCKEDBY: thread that is blocking a thread

20. jvmtop profiler
./jvmtop.sh --profile <PID>

21. References
Nathan Marz, "Your Code is Wrong":
www.slideshare.net/nathanmarz/your-code-is-wrong
http://www.youtube.com/watch?v=QOu4e5y6sg4
jps:
docs.oracle.com/javase/7/docs/technotes/tools/share/jps.html
jstatd:
docs.oracle.com/javase/7/docs/technotes/tools/share/jstatd.html
jstack:
docs.oracle.com/javase/7/docs/technotes/tools/share/jstack.html
jvmtop project:
code.google.com/p/jvmtop/

22. My Info
scott.leberknight@altamiracorp.com
@gmail.com
www.altamiracorp.com/blog
www.sleberknight.com/blog
twitter: sleberknight