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Table 1-13 Options to the jstat Command (continued)
Prints statistics of the sizes of the old generation
-gcoldcapacity
Prints statistics of the sizes of the permanent generation
-gcpermcapacity
Prints a summary of garbage collection statistics
-gcutil
Prints Java compilation method statistics
-printcompilation
A complete description of the jstat tool, including examples, can be found at:
http://java.sun.com/j2se/1.5.0/docs/tooldocs/share/jstat.html
Following is an example jstat command which attaches to pid 27395 and takes five samples
at 250 millisecond intervals. The -gcnew option specifies that statistics of the behavior of the
new generation is output.
$ jstat -gcnew 27395 250 5
S0C S1C S0U S1U TT MTT DSS EC EU YGC YGCT
64.0 64.0 0.0 31.7 31 31 32.0 512.0 178.6 249 0.203
64.0 64.0 0.0 31.7 31 31 32.0 512.0 355.5 249 0.203
64.0 64.0 35.4 0.0 2 31 32.0 512.0 21.9 250 0.204
64.0 64.0 35.4 0.0 2 31 32.0 512.0 245.9 250 0.204
64.0 64.0 35.4 0.0 2 31 32.0 512.0 421.1 250 0.204
Following is a description of the column headings in the example:
Table 1-14 jstat — New Generation Statistics
DescriptionColumn
Current survivor space 0 capacity (KB)S0C
Current survivor space 1 capacity (KB)S1C
Survivor space 0 utilization (KB)S0U
Survivor space 1 utilization (KB)S1U
Tenuring thresholdTT
Maximum tenuring thresholdMTT
Desired survivor size (KB)DSS
Current Eden space capacity (KB)EC
Eden space utilization (KB)EU
Number of young generation GC eventsYGC
Young generation garbage collection timeYGCT
1.18 jstatd (1.5+ only)
The jstatd tool launches an RMI (remote method invocation) server that monitors the creation
and termination of Java VMs and provides an interface to allow remote monitoring tools to attach
to Java VMs running on the local host.
For more information, refer to the following website:
http://java.sun.com/j2se/1.5.0/docs/tooldocs/share/jstatd.html
1.19 jvmstat Tools
The Java VM shipped with SDK 1.4.2 and later provides always-on instrumentation needed to
support monitoring tools and utilities.
1.18 jstatd (1.5+ only) 41