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I am new to jstat tool. Therefore I did a sample as below.
./jstat -gcutil -t 4001 5000 Timestamp S0 S1 E O P YGC YGCT FGC FGCT GCT 565088.4 0.00 0.89 75.86 40.59 84.80 405 3.822 4 0.549 4.371 565093.4 0.00 0.89 77.81 40.59 84.80 405 3.822 4 0.549 4.371 565098.4 0.00 0.89 77.81 40.59 84.80 405 3.822 4 0.549 4.371 565103.5 0.00 0.89 77.85 40.59 84.80 405 3.822 4 0.549 4.371 565108.5 0.00 0.89 77.85 40.59 84.80 405 3.822 4 0.549 4.371 565113.4 0.00 0.89 77.85 40.59 84.80 405 3.822 4 0.549 4.371 jstat -gc output S0C S1C S0U S1U EC EU OC OU PC PU YGC YGCT FGC FGCT GCT 704.0 704.0 0.4 0.0 6080.0 4013.8 14928.0 6335.2 21248.0 18019.6 436 3.957 4 0.549 4.506 704.0 704.0 0.4 0.0 6080.0 4016.6 14928.0 6335.2 21248.0 18019.6 436 3.957 4 0.549 4.506 704.0 704.0 0.4 0.0 6080.0 4135.4 14928.0 6335.2 21248.0 18019.6 436 3.957 4 0.549 4.506 704.0 704.0 0.4 0.0 6080.0 4135.4 14928.0 6335.2 21248.0 18019.6 436 3.957 4 0.549 4.506 704.0 704.0 0.4 0.0 6080.0 4135.4 14928.0 6335.2 21248.0 18019.6 436 3.957 4 0.549 4.506 704.0 704.0 0.4 0.0 6080.0 4135.4 14928.0 6335.2 21248.0 18019.6 436 3.957 4 0.549 4.506 What does this results indicates? Which are the columns to look out for possible memory problem e.g. memory leak etc.
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From the jstat usage message, we learn that the jstat command-line tool is executed by running the name of the command first ( jstat ) with the hyphenated option name next, followed by the optional -t and/or -h flags, followed by a vimid, and concluding with an optional interval and optional count of the number of ...
jstat is a simple utility tool, that is present in JDK to provide JVM performance-related statistics like garbage collection, compilation activities. The major strength of jstat is its ability to capture these metrics dynamically when JVM is running without any pre-requisite instrumentation.
Survivor Space: The pool containing objects that have survived the garbage collection of the Eden space. Tenured Generation or Old Gen: The pool containing objects that have existed for some time in the survivor space.
gcutil gives stats in terms of percentage utilization
-gcutil Option 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. gc gives statistics in terms of alloted space and utilized space.
-gc Option 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. Source : Docs
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