Dear Reader,
Today we will discuss about "jstat". This is Java Virtual Machine Statistics Monitoring Tool.
I use this for watching live GC activity during post Production Deployment specifically if our new build contains
some JVM tuning or we deploy some thread related fix. You might be using visualvm, jstack, jmap utilities for JVM
analysis, verbose-gc files for GC. However if your JVM supports, jstat is best tool for watching live GC activities of a Java Process.
The jstat tool displays performance statistics for an instrumented HotSpot Java virtual machine (JVM).
The below Headers will be displayed in Console report, hence Abbrev are given as below:
Summary of Garbage Collection Statistics:
Column Description
S0 Survivor space 0 utilization as a percentage of the space's current capacity.
S1 Survivor space 1 utilization as a percentage of the space's current capacity.
E Eden space utilization as a percentage of the space's current capacity.
O Old space utilization as a percentage of the space's current capacity.
P Permanent space utilization as a percentage of the space's current capacity.
YGC Number of young generation GC events.
YGCT Young generation garbage collection time.
FGC Number of full GC events.
FGCT Full garbage collection time.
GCT Total garbage collection time.
Complete Details:
E:\Tools>jstat -gcutil 8792 3000 (Java Process Id is 8792, 3000 is Milliseconds interval.)
S0 S1 E O P YGC YGCT FGC FGCT GCT
99.88 0.00 83.94 0.92 92.06 2 0.061 0 0.000 0.061
99.88 0.00 83.94 0.92 92.06 2 0.061 0 0.000 0.061
0.00 99.95 8.73 2.03 99.04 3 0.071 0 0.000 0.071
0.00 99.95 26.33 2.03 99.51 3 0.071 0 0.000 0.071
99.86 0.00 3.74 10.45 98.34 4 0.089 0 0.000 0.089
99.86 0.00 45.33 10.45 98.94 4 0.089 0 0.000 0.089
99.86 0.00 75.27 10.45 99.43 4 0.089 0 0.000 0.089
0.00 99.86 15.00 12.74 98.18 5 0.100 0 0.000 0.100
0.00 99.86 57.14 12.74 98.28 5 0.100 0 0.000 0.100
0.00 99.86 94.67 12.74 98.41 5 0.100 0 0.000 0.100
97.80 0.00 26.22 12.74 98.50 6 0.109 0 0.000 0.109
97.80 0.00 60.60 12.74 98.61 6 0.109 0 0.000 0.109
97.80 0.00 94.61 12.74 98.72 6 0.109 0 0.000 0.109
0.00 96.29 37.34 14.30 98.77 7 0.123 0 0.000 0.123
0.00 96.29 66.33 14.30 98.87 7 0.123 0 0.000 0.123
61.50 0.00 4.67 17.04 98.92 8 0.137 0 0.000 0.137
61.50 0.00 42.56 17.04 98.99 8 0.137 0 0.000 0.137
61.50 0.00 80.11 17.04 99.03 8 0.137 0 0.000 0.137
0.00 95.05 7.00 19.42 99.07 9 0.153 0 0.000 0.153
0.00 95.05 45.77 19.42 99.11 9 0.153 0 0.000 0.153
0.00 95.05 87.16 19.42 99.21 9 0.153 0 0.000 0.153
20.67 0.00 23.91 20.96 99.34 10 0.162 0 0.000 0.162
20.67 0.00 55.89 20.96 99.41 10 0.162 0 0.000 0.162
20.67 0.00 89.74 20.96 99.51 10 0.162 0 0.000 0.162
.....This will keep printing.....
If you have issue regarding ProcessId, use below command to know Processes Running:
jps -l -m -v
If you want only limited number of records to see, use below command:
E:\Tools>jstat -gcutil 8792 1000 6 (8792:ProcessId, 1000:1 Second interval, 6:Only 6 Rows to display and then exit.)
E:\Tools>jstat -gcutil -h4 8792 1000 100 (-h4: Will reprint Header S0, S1, E etc after every 4 Lines. Total 100 Lines here.)
Other type of argument is: "gc": Statistics of the behavior of the garbage collected heap.
-gc: Garbage-collected heap statistics
Column Description
S0C Current survivor space 0 capacity (KB).
S1C Current survivor space 1 capacity (KB).
S0U Survivor space 0 utilization (KB).
S1U Survivor space 1 utilization (KB).
EC Current eden space capacity (KB).
EU Eden space utilization (KB).
OC Current old space capacity (KB).
OU Old space utilization (KB).
PC Current permanent space capacity (KB).
PU Permanent space utilization (KB).
YGC Number of young generation GC Events.
YGCT Young generation garbage collection time.
FGC Number of full GC events.
FGCT Full garbage collection time.
GCT Total garbage collection time.
E:\Tools>jstat -gc 8792 5000 20
S0C S1C S0U S1U EC EU OC OU PC PU YGC YGCT FGC FGCT GCT
5120.0 5120.0 0.0 4129.1 77312.0 44305.7 175104.0 68584.6 49664.0 24834.0 105 1.065 1 0.096 1.161
5120.0 5120.0 0.0 4129.1 77312.0 46390.8 175104.0 68584.6 49664.0 24834.0 105 1.065 1 0.096 1.161
5120.0 5120.0 0.0 4129.1 77312.0 52546.8 175104.0 68584.6 49664.0 24834.0 105 1.065 1 0.096 1.161
5120.0 5120.0 5116.1 0.0 77312.0 210.1 175104.0 69184.6 49664.0 24834.4 106 1.078 1 0.096 1.174
5120.0 5120.0 5116.1 0.0 77312.0 36339.2 175104.0 69184.6 49664.0 24834.4 106 1.078 1 0.096 1.174
5120.0 5120.0 5116.1 0.0 77312.0 74165.2 175104.0 69184.6 49664.0 24834.4 106 1.078 1 0.096 1.174
5120.0 5120.0 0.0 4000.0 77312.0 27741.9 175104.0 71402.5 49664.0 24834.4 107 1.086 1 0.096 1.182
5120.0 5120.0 0.0 4000.0 77312.0 60018.1 175104.0 71402.5 49664.0 24834.4 107 1.086 1 0.096 1.182
5120.0 5120.0 3904.0 0.0 77312.0 16572.7 175104.0 73227.0 49664.0 24834.4 108 1.097 1 0.096 1.193
5120.0 5120.0 3904.0 0.0 77312.0 53046.6 175104.0 73227.0 49664.0 24834.5 108 1.097 1 0.096 1.193
5120.0 5120.0 0.0 3713.1 77312.0 8212.0 175104.0 74979.1 49664.0 24834.5 109 1.105 1 0.096 1.201
5120.0 5120.0 0.0 3713.1 77312.0 43119.1 175104.0 74979.1 49664.0 24834.5 109 1.105 1 0.096 1.201
5120.0 5120.0 4352.0 0.0 77312.0 1189.1 175104.0 76731.5 49664.0 24834.5 110 1.110 1 0.096 1.206
5120.0 5120.0 4352.0 0.0 77312.0 36556.2 175104.0 76731.5 49664.0 24834.5 110 1.110 1 0.096 1.206
5120.0 5120.0 4352.0 0.0 77312.0 68395.2 175104.0 76731.5 49664.0 24834.5 110 1.110 1 0.096 1.206
5120.0 5120.0 0.0 4353.1 77312.0 27265.7 175104.0 78299.5 49664.0 24834.5 111 1.117 1 0.096 1.213
More Details: http://docs.oracle.com/javase/7/docs/technotes/tools/share/jstat.html
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Monday, March 27, 2017
jstat : Java GC Statistics Details
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