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25.\" Software: JDK 8
rgallard04b0ca42014-10-17 11:33:22 -070026.\" Date: 03 March 2015
rgallardb6435452013-11-25 20:19:02 -080027.\" SectDesc: Monitoring Tools
28.\" Title: jstat.1
29.\"
30.if n .pl 99999
rgallard04b0ca42014-10-17 11:33:22 -070031.TH jstat 1 "03 March 2015" "JDK 8" "Monitoring Tools"
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49.\" * MAIN CONTENT STARTS HERE *
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tbell16c34dd2009-05-04 18:28:26 -070051
rgallardb6435452013-11-25 20:19:02 -080052.SH NAME
53jstat \- Monitors Java Virtual Machine (JVM) statistics\&. This command is experimental and unsupported\&.
54.SH SYNOPSIS
55.sp
56.nf
tbell16c34dd2009-05-04 18:28:26 -070057
rgallardb6435452013-11-25 20:19:02 -080058\fBjstat\fR [ \fIgeneralOption\fR | \fIoutputOptions vmid\fR [ \fIinterval\fR[s|ms] [ \fIcount \fR] ]
59.fi
60.sp
61.TP
62\fIgeneralOption\fR
63A single general command-line option \f3-help\fR or \f3-options\fR\&. See General Options\&.
64.TP
65\fIoutputOptions\fR
66One or more output options that consist of a single \f3statOption\fR, plus any of the \f3-t\fR, \f3-h\fR, and \f3-J\fR options\&. See Output Options\&.
67.TP
68\fIvmid\fR
69Virtual machine identifier, which is a string that indicates the target JVM\&. The general syntax is the following:
70.sp
71.nf
72\f3[protocol:][//]lvmid[@hostname[:port]/servername]\fP
73.fi
74.nf
75\f3\fP
76.fi
77.sp
tbell16c34dd2009-05-04 18:28:26 -070078
tbell16c34dd2009-05-04 18:28:26 -070079
rgallardb6435452013-11-25 20:19:02 -080080The syntax of the \f3vmid\fR string corresponds to the syntax of a URI\&. The \f3vmid\fR string can vary from a simple integer that represents a local JVM to a more complex construction that specifies a communications protocol, port number, and other implementation-specific values\&. See Virtual Machine Identifier\&.
81.TP
82\fIinterval\fR [s|ms]
83Sampling interval in the specified units, seconds (s) or milliseconds (ms)\&. Default units are milliseconds\&. Must be a positive integer\&. When specified, the \f3jstat\fR command produces its output at each interval\&.
84.TP
85\fIcount\fR
86Number of samples to display\&. The default value is infinity which causes the \f3jstat\fR command to display statistics until the target JVM terminates or the \f3jstat\fR command is terminated\&. This value must be a positive integer\&.
87.SH DESCRIPTION
88The \f3jstat\fR command displays performance statistics for an instrumented Java HotSpot VM\&. The target JVM is identified by its virtual machine identifier, or \f3vmid\fR option\&.
89.SH VIRTUAL\ MACHINE\ IDENTIFIER
90The syntax of the \f3vmid\fR string corresponds to the syntax of a URI:
91.sp
92.nf
93\f3[protocol:][//]lvmid[@hostname[:port]/servername]\fP
94.fi
95.nf
96\f3\fP
97.fi
98.sp
99.TP
100\fIprotocol\fR
101The communications protocol\&. If the \fIprotocol\fR value is omitted and a host name is not specified, then the default protocol is a platform-specific optimized local protocol\&. If the \fIprotocol\fR value is omitted and a host name is specified, then the default protocol is \f3rmi\fR\&.
102.TP
103\fIlvmid\fR
rgallard04b0ca42014-10-17 11:33:22 -0700104The local virtual machine identifier for the target JVM\&. The \f3lvmid\fR is a platform-specific value that uniquely identifies a JVM on a system\&. The \f3lvmid\fR is the only required component of a virtual machine identifier\&. The \f3lvmid\fR is typically, but not necessarily, the operating system\&'s process identifier for the target JVM process\&. You can use the \f3jps\fR command to determine the \f3lvmid\fR\&. Also, you can determine the \f3lvmid\fR on Solaris, Linux, and OS X platforms with the \f3ps\fR command, and on Windows with the Windows Task Manager\&.
rgallardb6435452013-11-25 20:19:02 -0800105.TP
106\fIhostname\fR
107A hostname or IP address that indicates the target host\&. If the \fIhostname\fR value is omitted, then the target host is the local host\&.
108.TP
109\fIport\fR
110The default port for communicating with the remote server\&. If the \fIhostname\fR value is omitted or the \fIprotocol\fR value specifies an optimized, local protocol, then the \fIport\fR value is ignored\&. Otherwise, treatment of the \f3port\fR parameter is implementation-specific\&. For the default \f3rmi\fR protocol, the port value indicates the port number for the rmiregistry on the remote host\&. If the \fIport\fR value is omitted and the \fIprotocol\fR value indicates \f3rmi\fR, then the default rmiregistry port (1099) is used\&.
111.TP
112\fIservername\fR
113The treatment of the \f3servername\fR parameter depends on implementation\&. For the optimized local protocol, this field is ignored\&. For the \f3rmi\fR protocol, it represents the name of the RMI remote object on the remote host\&.
114.SH OPTIONS
115The \f3jstat\fR command supports two types of options, general options and output options\&. General options cause the \f3jstat\fR command to display simple usage and version information\&. Output options determine the content and format of the statistical output\&.
116.PP
117All options and their functionality are subject to change or removal in future releases\&.
118.SS GENERAL\ OPTIONS
119If you specify one of the general options, then you cannot specify any other option or parameter\&.
120.TP
121-help
122.br
123Displays a help message\&.
124.TP
125-options
126.br
127Displays a list of static options\&. See Output Options\&.
128.SS OUTPUT\ OPTIONS
129If you do not specify a general option, then you can specify output options\&. Output options determine the content and format of the \f3jstat\fR command\&'s output, and consist of a single \f3statOption\fR, plus any of the other output options (\f3-h\fR, \f3-t\fR, and \f3-J\fR)\&. The \f3statOption\fR must come first\&.
130.PP
131Output is formatted as a table, with columns that are separated by spaces\&. A header row with titles describes the columns\&. Use the \f3-h\fR option to set the frequency at which the header is displayed\&. Column header names are consistent among the different options\&. In general, if two options provide a column with the same name, then the data source for the two columns is the same\&.
132.PP
133Use the \f3-t\fR option to display a time stamp column, labeled Timestamp as the first column of output\&. The Timestamp column contains the elapsed time, in seconds, since the target JVM started\&. The resolution of the time stamp is dependent on various factors and is subject to variation due to delayed thread scheduling on heavily loaded systems\&.
134.PP
135Use the interval and count parameters to determine how frequently and how many times, respectively, the \f3jstat\fR command displays its output\&.
136.PP
137\fINote:\fR Do not to write scripts to parse the \f3jstat\fR command\&'s output because the format might change in future releases\&. If you write scripts that parse \f3jstat\fR command output, then expect to modify them for future releases of this tool\&.
138.TP
139-\fIstatOption\fR
140.br
141Determines the statistics information the \f3jstat\fR command displays\&. The following lists the available options\&. Use the \f3-options\fR general option to display the list of options for a particular platform installation\&. See Stat Options and Output\&.
tbell16c34dd2009-05-04 18:28:26 -0700142
rgallardb6435452013-11-25 20:19:02 -0800143\f3class\fR: Displays statistics about the behavior of the class loader\&.
tbell16c34dd2009-05-04 18:28:26 -0700144
rgallardb6435452013-11-25 20:19:02 -0800145\f3compiler\fR: Displays statistics about the behavior of the Java HotSpot VM Just-in-Time compiler\&.
tbell16c34dd2009-05-04 18:28:26 -0700146
rgallardb6435452013-11-25 20:19:02 -0800147\f3gc\fR: Displays statistics about the behavior of the garbage collected heap\&.
tbell16c34dd2009-05-04 18:28:26 -0700148
rgallardb6435452013-11-25 20:19:02 -0800149\f3gccapacity\fR: Displays statistics about the capacities of the generations and their corresponding spaces\&.
tbell16c34dd2009-05-04 18:28:26 -0700150
rgallardb6435452013-11-25 20:19:02 -0800151\f3gccause\fR: Displays a summary about garbage collection statistics (same as \f3-gcutil\fR), with the cause of the last and current (when applicable) garbage collection events\&.
tbell16c34dd2009-05-04 18:28:26 -0700152
rgallardb6435452013-11-25 20:19:02 -0800153\f3gcnew\fR: Displays statistics of the behavior of the new generation\&.
tbell16c34dd2009-05-04 18:28:26 -0700154
rgallardb6435452013-11-25 20:19:02 -0800155\f3gcnewcapacity\fR: Displays statistics about the sizes of the new generations and its corresponding spaces\&.
tbell16c34dd2009-05-04 18:28:26 -0700156
rgallard04b0ca42014-10-17 11:33:22 -0700157\f3gcold\fR: Displays statistics about the behavior of the old generation and metaspace statistics\&.
tbell16c34dd2009-05-04 18:28:26 -0700158
rgallardb6435452013-11-25 20:19:02 -0800159\f3gcoldcapacity\fR: Displays statistics about the sizes of the old generation\&.
tbell16c34dd2009-05-04 18:28:26 -0700160
rgallardb6435452013-11-25 20:19:02 -0800161\f3gcmetacapacity\fR: Displays statistics about the sizes of the metaspace\&.
tbell16c34dd2009-05-04 18:28:26 -0700162
rgallardb6435452013-11-25 20:19:02 -0800163\f3gcutil\fR: Displays a summary about garbage collection statistics\&.
tbell16c34dd2009-05-04 18:28:26 -0700164
rgallardb6435452013-11-25 20:19:02 -0800165\f3printcompilation\fR: Displays Java HotSpot VM compilation method statistics\&.
166.TP
167-h \fIn\fR
duke6e45e102007-12-01 00:00:00 +0000168.br
rgallardb6435452013-11-25 20:19:02 -0800169Displays a column header every \fIn\fR samples (output rows), where \fIn\fR is a positive integer\&. Default value is 0, which displays the column header the first row of data\&.
170.TP
171-t
duke6e45e102007-12-01 00:00:00 +0000172.br
rgallard04b0ca42014-10-17 11:33:22 -0700173Displays a timestamp column as the first column of output\&. The time stamp is the time since the start time of the target JVM\&.
rgallardb6435452013-11-25 20:19:02 -0800174.TP
175-J\fIjavaOption\fR
duke6e45e102007-12-01 00:00:00 +0000176.br
rgallardb6435452013-11-25 20:19:02 -0800177Passes \f3javaOption\fR to the Java application launcher\&. For example, \f3-J-Xms48m\fR sets the startup memory to 48 MB\&. For a complete list of options, see java(1)\&.
178.SS STAT\ OPTIONS\ AND\ OUTPUT
179The following information summarizes the columns that the \f3jstat\fR command outputs for each \fIstatOption\fR\&.
180.TP
181-class \fIoption\fR
duke6e45e102007-12-01 00:00:00 +0000182.br
rgallardb6435452013-11-25 20:19:02 -0800183Class loader statistics\&.
tbell16c34dd2009-05-04 18:28:26 -0700184
rgallardb6435452013-11-25 20:19:02 -0800185\f3Loaded\fR: Number of classes loaded\&.
tbell16c34dd2009-05-04 18:28:26 -0700186
rgallard04b0ca42014-10-17 11:33:22 -0700187\f3Bytes\fR: Number of kBs loaded\&.
tbell16c34dd2009-05-04 18:28:26 -0700188
rgallardb6435452013-11-25 20:19:02 -0800189\f3Unloaded\fR: Number of classes unloaded\&.
tbell16c34dd2009-05-04 18:28:26 -0700190
rgallardb6435452013-11-25 20:19:02 -0800191\f3Bytes\fR: Number of Kbytes unloaded\&.
tbell16c34dd2009-05-04 18:28:26 -0700192
rgallardb6435452013-11-25 20:19:02 -0800193\f3Time\fR: Time spent performing class loading and unloading operations\&.
194.TP
195-compiler \fIoption\fR
duke6e45e102007-12-01 00:00:00 +0000196.br
rgallardb6435452013-11-25 20:19:02 -0800197Java HotSpot VM Just-in-Time compiler statistics\&.
198
199\f3Compiled\fR: Number of compilation tasks performed\&.
200
201\f3Failed\fR: Number of compilations tasks failed\&.
202
203\f3Invalid\fR: Number of compilation tasks that were invalidated\&.
204
205\f3Time\fR: Time spent performing compilation tasks\&.
206
207\f3FailedType\fR: Compile type of the last failed compilation\&.
208
209\f3FailedMethod\fR: Class name and method of the last failed compilation\&.
210.TP
211-gc \fIoption\fR
duke6e45e102007-12-01 00:00:00 +0000212.br
rgallardb6435452013-11-25 20:19:02 -0800213Garbage-collected heap statistics\&.
214
rgallard04b0ca42014-10-17 11:33:22 -0700215\f3S0C\fR: Current survivor space 0 capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800216
rgallard04b0ca42014-10-17 11:33:22 -0700217\f3S1C\fR: Current survivor space 1 capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800218
rgallard04b0ca42014-10-17 11:33:22 -0700219\f3S0U\fR: Survivor space 0 utilization (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800220
rgallard04b0ca42014-10-17 11:33:22 -0700221\f3S1U\fR: Survivor space 1 utilization (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800222
rgallard04b0ca42014-10-17 11:33:22 -0700223\f3EC\fR: Current eden space capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800224
rgallard04b0ca42014-10-17 11:33:22 -0700225\f3EU\fR: Eden space utilization (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800226
rgallard04b0ca42014-10-17 11:33:22 -0700227\f3OC\fR: Current old space capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800228
rgallard04b0ca42014-10-17 11:33:22 -0700229\f3OU\fR: Old space utilization (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800230
rgallard04b0ca42014-10-17 11:33:22 -0700231\f3MC\fR: Metaspace capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800232
rgallard04b0ca42014-10-17 11:33:22 -0700233\f3MU\fR: Metacspace utilization (kB)\&.
234
235\f3CCSC\fR: Compressed class space capacity (kB)\&.
236
237\f3CCSU\fR: Compressed class space used (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800238
239\f3YGC\fR: Number of young generation garbage collection events\&.
240
241\f3YGCT\fR: Young generation garbage collection time\&.
242
243\f3FGC\fR: Number of full GC events\&.
244
245\f3FGCT\fR: Full garbage collection time\&.
246
247\f3GCT\fR: Total garbage collection time\&.
248.TP
249-gccapacity \fIoption\fR
duke6e45e102007-12-01 00:00:00 +0000250.br
rgallardb6435452013-11-25 20:19:02 -0800251Memory pool generation and space capacities\&.
252
rgallard04b0ca42014-10-17 11:33:22 -0700253\f3NGCMN\fR: Minimum new generation capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800254
rgallard04b0ca42014-10-17 11:33:22 -0700255\f3NGCMX\fR: Maximum new generation capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800256
rgallard04b0ca42014-10-17 11:33:22 -0700257\f3NGC\fR: Current new generation capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800258
rgallard04b0ca42014-10-17 11:33:22 -0700259\f3S0C\fR: Current survivor space 0 capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800260
rgallard04b0ca42014-10-17 11:33:22 -0700261\f3S1C\fR: Current survivor space 1 capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800262
rgallard04b0ca42014-10-17 11:33:22 -0700263\f3EC\fR: Current eden space capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800264
rgallard04b0ca42014-10-17 11:33:22 -0700265\f3OGCMN\fR: Minimum old generation capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800266
rgallard04b0ca42014-10-17 11:33:22 -0700267\f3OGCMX\fR: Maximum old generation capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800268
rgallard04b0ca42014-10-17 11:33:22 -0700269\f3OGC\fR: Current old generation capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800270
rgallard04b0ca42014-10-17 11:33:22 -0700271\f3OC\fR: Current old space capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800272
rgallard04b0ca42014-10-17 11:33:22 -0700273\f3MCMN\fR: Minimum metaspace capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800274
rgallard04b0ca42014-10-17 11:33:22 -0700275\f3MCMX\fR: Maximum metaspace capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800276
rgallard04b0ca42014-10-17 11:33:22 -0700277\f3MC\fR: Metaspace capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800278
rgallard04b0ca42014-10-17 11:33:22 -0700279\f3CCSMN\fR: Compressed class space minimum capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800280
rgallard04b0ca42014-10-17 11:33:22 -0700281\f3CCSMX\fR: Compressed class space maximum capacity (kB)\&.
282
283\f3CCSC\fR: Compressed class space capacity (kB)\&.
284
285\f3YGC\fR: Number of young generation GC events\&.
286
287\f3FGC\fR: Number of full GC events\&.
rgallardb6435452013-11-25 20:19:02 -0800288.TP
289-gccause \fIoption\fR
duke6e45e102007-12-01 00:00:00 +0000290.br
rgallardb6435452013-11-25 20:19:02 -0800291This option displays the same summary of garbage collection statistics as the \f3-gcutil\fR option, but includes the causes of the last garbage collection event and (when applicable) the current garbage collection event\&. In addition to the columns listed for \f3-gcutil\fR, this option adds the following columns\&.
292
rgallard04b0ca42014-10-17 11:33:22 -0700293\f3LGCC\fR: Cause of last garbage collection
rgallardb6435452013-11-25 20:19:02 -0800294
rgallard04b0ca42014-10-17 11:33:22 -0700295\f3GCC\fR: Cause of current garbage collection
rgallardb6435452013-11-25 20:19:02 -0800296.TP
297-gcnew \fIoption\fR
duke6e45e102007-12-01 00:00:00 +0000298.br
rgallardb6435452013-11-25 20:19:02 -0800299New generation statistics\&.
300
rgallard04b0ca42014-10-17 11:33:22 -0700301\f3S0C\fR: Current survivor space 0 capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800302
rgallard04b0ca42014-10-17 11:33:22 -0700303\f3S1C\fR: Current survivor space 1 capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800304
rgallard04b0ca42014-10-17 11:33:22 -0700305\f3S0U\fR: Survivor space 0 utilization (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800306
rgallard04b0ca42014-10-17 11:33:22 -0700307\f3S1U\fR: Survivor space 1 utilization (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800308
309\f3TT\fR: Tenuring threshold\&.
310
311\f3MTT\fR: Maximum tenuring threshold\&.
312
rgallard04b0ca42014-10-17 11:33:22 -0700313\f3DSS\fR: Desired survivor size (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800314
rgallard04b0ca42014-10-17 11:33:22 -0700315\f3EC\fR: Current eden space capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800316
rgallard04b0ca42014-10-17 11:33:22 -0700317\f3EU\fR: Eden space utilization (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800318
319\f3YGC\fR: Number of young generation GC events\&.
320
321\f3YGCT\fR: Young generation garbage collection time\&.
322.TP
323-gcnewcapacity \fIoption\fR
duke6e45e102007-12-01 00:00:00 +0000324.br
rgallardb6435452013-11-25 20:19:02 -0800325New generation space size statistics\&.
tbell16c34dd2009-05-04 18:28:26 -0700326
rgallard04b0ca42014-10-17 11:33:22 -0700327\f3NGCMN\fR: Minimum new generation capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800328
rgallard04b0ca42014-10-17 11:33:22 -0700329\f3NGCMX\fR: Maximum new generation capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800330
rgallard04b0ca42014-10-17 11:33:22 -0700331\f3NGC\fR: Current new generation capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800332
rgallard04b0ca42014-10-17 11:33:22 -0700333\f3S0CMX\fR: Maximum survivor space 0 capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800334
rgallard04b0ca42014-10-17 11:33:22 -0700335\f3S0C\fR: Current survivor space 0 capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800336
rgallard04b0ca42014-10-17 11:33:22 -0700337\f3S1CMX\fR: Maximum survivor space 1 capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800338
rgallard04b0ca42014-10-17 11:33:22 -0700339\f3S1C\fR: Current survivor space 1 capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800340
rgallard04b0ca42014-10-17 11:33:22 -0700341\f3ECMX\fR: Maximum eden space capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800342
rgallard04b0ca42014-10-17 11:33:22 -0700343\f3EC\fR: Current eden space capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800344
345\f3YGC\fR: Number of young generation GC events\&.
346
rgallard04b0ca42014-10-17 11:33:22 -0700347\f3FGC\fR: Number of full GC events\&.
rgallardb6435452013-11-25 20:19:02 -0800348.TP
349-gcold \fIoption\fR
duke6e45e102007-12-01 00:00:00 +0000350.br
rgallard04b0ca42014-10-17 11:33:22 -0700351Old and permanent generation statistics\&.
duke6e45e102007-12-01 00:00:00 +0000352
rgallard04b0ca42014-10-17 11:33:22 -0700353\f3MC\fR: Metaspace capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800354
rgallard04b0ca42014-10-17 11:33:22 -0700355\f3MU\fR: Metaspace utilization (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800356
rgallard04b0ca42014-10-17 11:33:22 -0700357\f3CCSC\fR: Compressed class space capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800358
rgallard04b0ca42014-10-17 11:33:22 -0700359\f3CCSU\fR: Compressed class space used (kB)\&.
360
361\f3OC\fR: Current old space capacity (kB)\&.
362
363\f3OU\fR: Old space utilization (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800364
365\f3YGC\fR: Number of young generation GC events\&.
366
367\f3FGC\fR: Number of full GC events\&.
368
369\f3FGCT\fR: Full garbage collection time\&.
370
371\f3GCT\fR: Total garbage collection time\&.
372.TP
373-gcoldcapacity \fIoption\fR
duke6e45e102007-12-01 00:00:00 +0000374.br
rgallardb6435452013-11-25 20:19:02 -0800375Old generation statistics\&.
duke6e45e102007-12-01 00:00:00 +0000376
rgallard04b0ca42014-10-17 11:33:22 -0700377\f3OGCMN\fR: Minimum old generation capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800378
rgallard04b0ca42014-10-17 11:33:22 -0700379\f3OGCMX\fR: Maximum old generation capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800380
rgallard04b0ca42014-10-17 11:33:22 -0700381\f3OGC\fR: Current old generation capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800382
rgallard04b0ca42014-10-17 11:33:22 -0700383\f3OC\fR: Current old space capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800384
385\f3YGC\fR: Number of young generation GC events\&.
386
387\f3FGC\fR: Number of full GC events\&.
388
389\f3FGCT\fR: Full garbage collection time\&.
390
391\f3GCT\fR: Total garbage collection time\&.
392.TP
393-gcmetacapacity \fIoption\fR
duke6e45e102007-12-01 00:00:00 +0000394.br
rgallardb6435452013-11-25 20:19:02 -0800395Permanent generation statistics\&.
duke6e45e102007-12-01 00:00:00 +0000396
rgallard04b0ca42014-10-17 11:33:22 -0700397\f3MCMN\fR: Minimum metaspace capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800398
rgallard04b0ca42014-10-17 11:33:22 -0700399\f3MCMX\fR: Maximum metaspace capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800400
rgallard04b0ca42014-10-17 11:33:22 -0700401\f3MC\fR: Metaspace capacity (kB)\&.
402
403\f3CCSMN\fR: Compressed class space minimum capacity (kB)\&.
404
405\f3CCSMX\fR: Compressed class space maximum capacity (kB)\&.
rgallardb6435452013-11-25 20:19:02 -0800406
407\f3YGC\fR: Number of young generation GC events\&.
408
409\f3FGC\fR: Number of full GC events\&.
410
411\f3FGCT\fR: Full garbage collection time\&.
412
413\f3GCT\fR: Total garbage collection time\&.
414.TP
415-gcutil \fIoption\fR
duke6e45e102007-12-01 00:00:00 +0000416.br
rgallardb6435452013-11-25 20:19:02 -0800417Summary of garbage collection statistics\&.
duke6e45e102007-12-01 00:00:00 +0000418
rgallardb6435452013-11-25 20:19:02 -0800419\f3S0\fR: Survivor space 0 utilization as a percentage of the space\&'s current capacity\&.
420
421\f3S1\fR: Survivor space 1 utilization as a percentage of the space\&'s current capacity\&.
422
423\f3E\fR: Eden space utilization as a percentage of the space\&'s current capacity\&.
424
425\f3O\fR: Old space utilization as a percentage of the space\&'s current capacity\&.
426
427\f3M\fR: Metaspace utilization as a percentage of the space\&'s current capacity\&.
428
rgallard04b0ca42014-10-17 11:33:22 -0700429\f3CCS\fR: Compressed class space utilization as a percentage\&.
430
rgallardb6435452013-11-25 20:19:02 -0800431\f3YGC\fR: Number of young generation GC events\&.
432
433\f3YGCT\fR: Young generation garbage collection time\&.
434
435\f3FGC\fR: Number of full GC events\&.
436
437\f3FGCT\fR: Full garbage collection time\&.
438
439\f3GCT\fR: Total garbage collection time\&.
440.TP
441-printcompilation \fIoption\fR
duke6e45e102007-12-01 00:00:00 +0000442.br
rgallardb6435452013-11-25 20:19:02 -0800443Java HotSpot VM compiler method statistics\&.
duke6e45e102007-12-01 00:00:00 +0000444
rgallardb6435452013-11-25 20:19:02 -0800445\f3Compiled\fR: Number of compilation tasks performed by the most recently compiled method\&.
duke6e45e102007-12-01 00:00:00 +0000446
rgallardb6435452013-11-25 20:19:02 -0800447\f3Size\fR: Number of bytes of byte code of the most recently compiled method\&.
duke6e45e102007-12-01 00:00:00 +0000448
rgallardb6435452013-11-25 20:19:02 -0800449\f3Type\fR: Compilation type of the most recently compiled method\&.
duke6e45e102007-12-01 00:00:00 +0000450
rgallard04b0ca42014-10-17 11:33:22 -0700451\f3Method\fR: Class name and method name identifying the most recently compiled method\&. Class name uses slash (/) instead of dot (\&.) as a name space separator\&. Method name is the method within the specified class\&. The format for these two fields is consistent with the HotSpot \f3-XX:+PrintCompilation\fR option\&.
rgallardb6435452013-11-25 20:19:02 -0800452.SH EXAMPLES
453This section presents some examples of monitoring a local JVM with an \fIlvmid\fR of 21891\&.
454.SS THE\ GCUTIL\ OPTION
455This example attaches to lvmid 21891 and takes 7 samples at 250 millisecond intervals and displays the output as specified by the -\f3gcutil\fR option\&.
456.PP
rgallard04b0ca42014-10-17 11:33:22 -0700457The output of this example shows that a young generation collection occurred between the third and fourth sample\&. The collection took 0\&.078 seconds and promoted objects from the eden space (E) to the old space (O), resulting in an increase of old space utilization from 66\&.80% to 68\&.19%\&. Before the collection, the survivor space was 97\&.02% utilized, but after this collection it is 91\&.03% utilized\&.
rgallardb6435452013-11-25 20:19:02 -0800458.sp
459.nf
460\f3jstat \-gcutil 21891 250 7\fP
461.fi
462.nf
rgallard04b0ca42014-10-17 11:33:22 -0700463\f3 S0 S1 E O M CCS YGC YGCT FGC FGCT GCT \fP
rgallardb6435452013-11-25 20:19:02 -0800464.fi
465.nf
rgallard04b0ca42014-10-17 11:33:22 -0700466\f3 0\&.00 97\&.02 70\&.31 66\&.80 95\&.52 89\&.14 7 0\&.300 0 0\&.000 0\&.300\fP
rgallardb6435452013-11-25 20:19:02 -0800467.fi
468.nf
rgallard04b0ca42014-10-17 11:33:22 -0700469\f3 0\&.00 97\&.02 86\&.23 66\&.80 95\&.52 89\&.14 7 0\&.300 0 0\&.000 0\&.300\fP
rgallardb6435452013-11-25 20:19:02 -0800470.fi
471.nf
rgallard04b0ca42014-10-17 11:33:22 -0700472\f3 0\&.00 97\&.02 96\&.53 66\&.80 95\&.52 89\&.14 7 0\&.300 0 0\&.000 0\&.300\fP
rgallardb6435452013-11-25 20:19:02 -0800473.fi
474.nf
rgallard04b0ca42014-10-17 11:33:22 -0700475\f3 91\&.03 0\&.00 1\&.98 68\&.19 95\&.89 91\&.24 8 0\&.378 0 0\&.000 0\&.378\fP
rgallardb6435452013-11-25 20:19:02 -0800476.fi
477.nf
rgallard04b0ca42014-10-17 11:33:22 -0700478\f3 91\&.03 0\&.00 15\&.82 68\&.19 95\&.89 91\&.24 8 0\&.378 0 0\&.000 0\&.378\fP
rgallardb6435452013-11-25 20:19:02 -0800479.fi
480.nf
rgallard04b0ca42014-10-17 11:33:22 -0700481\f3 91\&.03 0\&.00 17\&.80 68\&.19 95\&.89 91\&.24 8 0\&.378 0 0\&.000 0\&.378\fP
rgallardb6435452013-11-25 20:19:02 -0800482.fi
483.nf
rgallard04b0ca42014-10-17 11:33:22 -0700484\f3 91\&.03 0\&.00 17\&.80 68\&.19 95\&.89 91\&.24 8 0\&.378 0 0\&.000 0\&.378\fP
rgallardb6435452013-11-25 20:19:02 -0800485.fi
486.sp
487.SS REPEAT\ THE\ COLUMN\ HEADER\ STRING
rgallard04b0ca42014-10-17 11:33:22 -0700488This example attaches to lvmid 21891 and takes samples at 250 millisecond intervals and displays the output as specified by \f3-gcnew\fR option\&. In addition, it uses the \f3-h3\fR option to output the column header after every 3 lines of data\&.
rgallardb6435452013-11-25 20:19:02 -0800489.PP
490In addition to showing the repeating header string, this example shows that between the second and third samples, a young GC occurred\&. Its duration was 0\&.001 seconds\&. The collection found enough active data that the survivor space 0 utilization (S0U) would have exceeded the desired survivor Size (DSS)\&. As a result, objects were promoted to the old generation (not visible in this output), and the tenuring threshold (TT) was lowered from 31 to 2\&.
491.PP
492Another collection occurs between the fifth and sixth samples\&. This collection found very few survivors and returned the tenuring threshold to 31\&.
493.sp
494.nf
495\f3jstat \-gcnew \-h3 21891 250\fP
496.fi
497.nf
498\f3 S0C S1C S0U S1U TT MTT DSS EC EU YGC YGCT\fP
499.fi
500.nf
501\f3 64\&.0 64\&.0 0\&.0 31\&.7 31 31 32\&.0 512\&.0 178\&.6 249 0\&.203\fP
502.fi
503.nf
504\f3 64\&.0 64\&.0 0\&.0 31\&.7 31 31 32\&.0 512\&.0 355\&.5 249 0\&.203\fP
505.fi
506.nf
507\f3 64\&.0 64\&.0 35\&.4 0\&.0 2 31 32\&.0 512\&.0 21\&.9 250 0\&.204\fP
508.fi
509.nf
510\f3 S0C S1C S0U S1U TT MTT DSS EC EU YGC YGCT\fP
511.fi
512.nf
513\f3 64\&.0 64\&.0 35\&.4 0\&.0 2 31 32\&.0 512\&.0 245\&.9 250 0\&.204\fP
514.fi
515.nf
516\f3 64\&.0 64\&.0 35\&.4 0\&.0 2 31 32\&.0 512\&.0 421\&.1 250 0\&.204\fP
517.fi
518.nf
519\f3 64\&.0 64\&.0 0\&.0 19\&.0 31 31 32\&.0 512\&.0 84\&.4 251 0\&.204\fP
520.fi
521.nf
522\f3 S0C S1C S0U S1U TT MTT DSS EC EU YGC YGCT\fP
523.fi
524.nf
525\f3 64\&.0 64\&.0 0\&.0 19\&.0 31 31 32\&.0 512\&.0 306\&.7 251 0\&.204\fP
526.fi
527.nf
528\f3\fP
529.fi
530.sp
531.SS INCLUDE\ A\ TIME\ STAMP\ FOR\ EACH\ SAMPLE
532This example attaches to lvmid 21891 and takes 3 samples at 250 millisecond intervals\&. The \f3-t\fR option is used to generate a time stamp for each sample in the first column\&.
533.PP
rgallard04b0ca42014-10-17 11:33:22 -0700534The Timestamp column reports the elapsed time in seconds since the start of the target JVM\&. In addition, the \f3-gcoldcapacity\fR output shows the old generation capacity (OGC) and the old space capacity (OC) increasing as the heap expands to meet allocation or promotion demands\&. The old generation capacity (OGC) has grown from 11,696 kB to 13,820 kB after the eighty-first full garbage collection (FGC)\&. The maximum capacity of the generation (and space) is 60,544 kB (OGCMX), so it still has room to expand\&.
rgallardb6435452013-11-25 20:19:02 -0800535.sp
536.nf
537\f3Timestamp OGCMN OGCMX OGC OC YGC FGC FGCT GCT\fP
538.fi
539.nf
540\f3 150\&.1 1408\&.0 60544\&.0 11696\&.0 11696\&.0 194 80 2\&.874 3\&.799\fP
541.fi
542.nf
543\f3 150\&.4 1408\&.0 60544\&.0 13820\&.0 13820\&.0 194 81 2\&.938 3\&.863\fP
544.fi
545.nf
546\f3 150\&.7 1408\&.0 60544\&.0 13820\&.0 13820\&.0 194 81 2\&.938 3\&.863\fP
547.fi
548.nf
549\f3\fP
550.fi
551.sp
552.SS MONITOR\ INSTRUMENTATION\ FOR\ A\ REMOTE\ JVM
553This example attaches to lvmid 40496 on the system named remote\&.domain using the \f3-gcutil\fR option, with samples taken every second indefinitely\&.
554.PP
rgallard04b0ca42014-10-17 11:33:22 -0700555The lvmid is combined with the name of the remote host to construct a \fIvmid\fR of \f340496@remote\&.domain\fR\&. This vmid results in the use of the \f3rmi\fR protocol to communicate to the default \f3jstatd\fR server on the remote host\&. The \f3jstatd\fR server is located using the \f3rmiregistry\fR command on \f3remote\&.domain\fR that is bound to the default port of the \f3rmiregistry\fR command (port 1099)\&.
rgallardb6435452013-11-25 20:19:02 -0800556.sp
557.nf
558\f3jstat \-gcutil 40496@remote\&.domain 1000\fP
559.fi
560.nf
561\f3\fI\&.\&.\&. output omitted\fR\fP
562.fi
563.nf
564\f3\fP
565.fi
566.sp
567.SH SEE\ ALSO
568.TP 0.2i
569\(bu
570java(1)
571.TP 0.2i
572\(bu
573jps(1)
574.TP 0.2i
575\(bu
576jstatd(1)
577.TP 0.2i
578\(bu
579rmiregistry(1)
580.RE
581.br
582'pl 8.5i
583'bp