'\" t+
−
.\"  Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved.+
−
.\"+
−
.\" DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.+
−
.\"+
−
.\" This code is free software; you can redistribute it and/or modify it+
−
.\" under the terms of the GNU General Public License version 2 only, as+
−
.\" published by the Free Software Foundation.+
−
.\"+
−
.\" This code is distributed in the hope that it will be useful, but WITHOUT+
−
.\" ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or+
−
.\" FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License+
−
.\" version 2 for more details (a copy is included in the LICENSE file that+
−
.\" accompanied this code).+
−
.\"+
−
.\" You should have received a copy of the GNU General Public License version+
−
.\" 2 along with this work; if not, write to the Free Software Foundation,+
−
.\" Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.+
−
.\"+
−
.\" Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA+
−
.\" or visit www.oracle.com if you need additional information or have any+
−
.\" questions.+
−
.\"+
−
.\"     Arch: generic+
−
.\"     Software: JDK 8+
−
.\"     Date: 10 May 2011+
−
.\"     SectDesc: Monitoring Tools+
−
.\"     Title: jstat.1+
−
.\"+
−
.if n .pl 99999+
−
.TH jstat 1 "10 May 2011" "JDK 8" "Monitoring Tools"+
−
.\" -----------------------------------------------------------------+
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.\" * Define some portability stuff+
−
.\" -----------------------------------------------------------------+
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
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.\" http://bugs.debian.org/507673+
−
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html+
−
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
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.ie \n(.g .ds Aq \(aq+
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.el       .ds Aq '+
−
.\" -----------------------------------------------------------------+
−
.\" * set default formatting+
−
.\" -----------------------------------------------------------------+
−
.\" disable hyphenation+
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.nh+
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.\" disable justification (adjust text to left margin only)+
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.ad l+
−
.\" -----------------------------------------------------------------+
−
.\" * MAIN CONTENT STARTS HERE *+
−
.\" -----------------------------------------------------------------+
−
+
−
.SH NAME    +
−
jstat \- Monitors Java Virtual Machine (JVM) statistics\&. This command is experimental and unsupported\&.+
−
.SH SYNOPSIS    +
−
.sp     +
−
.nf     +
−
+
−
\fBjstat\fR [ \fIgeneralOption\fR | \fIoutputOptions vmid\fR [ \fIinterval\fR[s|ms] [ \fIcount \fR] ]+
−
.fi     +
−
.sp     +
−
.TP     +
−
\fIgeneralOption\fR+
−
A single general command-line option \f3-help\fR or \f3-options\fR\&. See General Options\&.+
−
.TP     +
−
\fIoutputOptions\fR+
−
One 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\&.+
−
.TP     +
−
\fIvmid\fR+
−
Virtual machine identifier, which is a string that indicates the target JVM\&. The general syntax is the following:+
−
.sp     +
−
.nf     +
−
\f3[protocol:][//]lvmid[@hostname[:port]/servername]\fP+
−
.fi     +
−
.nf     +
−
\f3\fP+
−
.fi     +
−
.sp     +
−
+
−
+
−
The 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\&.+
−
.TP     +
−
\fIinterval\fR [s|ms]+
−
Sampling 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\&.+
−
.TP     +
−
\fIcount\fR+
−
Number 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\&.+
−
.SH DESCRIPTION    +
−
The \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\&.+
−
.SH VIRTUAL\ MACHINE\ IDENTIFIER    +
−
The syntax of the \f3vmid\fR string corresponds to the syntax of a URI:+
−
.sp     +
−
.nf     +
−
\f3[protocol:][//]lvmid[@hostname[:port]/servername]\fP+
−
.fi     +
−
.nf     +
−
\f3\fP+
−
.fi     +
−
.sp     +
−
.TP     +
−
\fIprotocol\fR+
−
The 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\&.+
−
.TP     +
−
\fIlvmid\fR+
−
The 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 UNIX platforms with the \f3ps\fR command, and on Windows with the Windows Task Manager\&.+
−
.TP     +
−
\fIhostname\fR+
−
A hostname or IP address that indicates the target host\&. If the \fIhostname\fR value is omitted, then the target host is the local host\&.+
−
.TP     +
−
\fIport\fR+
−
The 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\&.+
−
.TP     +
−
\fIservername\fR+
−
The 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\&.+
−
.SH OPTIONS    +
−
The \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\&.+
−
.PP+
−
All options and their functionality are subject to change or removal in future releases\&.+
−
.SS GENERAL\ OPTIONS    +
−
If you specify one of the general options, then you cannot specify any other option or parameter\&.+
−
.TP+
−
-help+
−
.br+
−
Displays a help message\&.+
−
.TP+
−
-options+
−
.br+
−
Displays a list of static options\&. See Output Options\&.+
−
.SS OUTPUT\ OPTIONS    +
−
If 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\&.+
−
.PP+
−
Output 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\&.+
−
.PP+
−
Use 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\&.+
−
.PP+
−
Use the interval and count parameters to determine how frequently and how many times, respectively, the \f3jstat\fR command displays its output\&.+
−
.PP+
−
\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\&.+
−
.TP+
−
-\fIstatOption\fR+
−
.br+
−
Determines 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\&.+
−
+
−
\f3class\fR: Displays statistics about the behavior of the class loader\&.+
−
+
−
\f3compiler\fR: Displays statistics about the behavior of the Java HotSpot VM Just-in-Time compiler\&.+
−
+
−
\f3gc\fR: Displays statistics about the behavior of the garbage collected heap\&.+
−
+
−
\f3gccapacity\fR: Displays statistics about the capacities of the generations and their corresponding spaces\&.+
−
+
−
\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\&.+
−
+
−
\f3gcnew\fR: Displays statistics of the behavior of the new generation\&.+
−
+
−
\f3gcnewcapacity\fR: Displays statistics about the sizes of the new generations and its corresponding spaces\&.+
−
+
−
\f3gcold\fR: Displays statistics about the behavior of the old generation and Metaspace Statistics\&.+
−
+
−
\f3gcoldcapacity\fR: Displays statistics about the sizes of the old generation\&.+
−
+
−
\f3gcmetacapacity\fR: Displays statistics about the sizes of the metaspace\&.+
−
+
−
\f3gcutil\fR: Displays a summary about garbage collection statistics\&.+
−
+
−
\f3printcompilation\fR: Displays Java HotSpot VM compilation method statistics\&.+
−
.TP+
−
-h \fIn\fR+
−
.br+
−
Displays 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\&.+
−
.TP+
−
-t+
−
.br+
−
Display sa timestamp column as the first column of output\&. The time stamp is the time since the start time of the target JVM\&.+
−
.TP+
−
-J\fIjavaOption\fR+
−
.br+
−
Passes \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)\&.+
−
.SS STAT\ OPTIONS\ AND\ OUTPUT    +
−
The following information summarizes the columns that the \f3jstat\fR command outputs for each \fIstatOption\fR\&.+
−
.TP+
−
-class \fIoption\fR+
−
.br+
−
Class loader statistics\&.+
−
+
−
\f3Loaded\fR: Number of classes loaded\&.+
−
+
−
\f3Bytes\fR: Number of KBs loaded\&.+
−
+
−
\f3Unloaded\fR: Number of classes unloaded\&.+
−
+
−
\f3Bytes\fR: Number of Kbytes unloaded\&.+
−
+
−
\f3Time\fR: Time spent performing class loading and unloading operations\&.+
−
.TP+
−
-compiler \fIoption\fR+
−
.br+
−
Java HotSpot VM Just-in-Time compiler statistics\&.+
−
+
−
\f3Compiled\fR: Number of compilation tasks performed\&.+
−
+
−
\f3Failed\fR: Number of compilations tasks failed\&.+
−
+
−
\f3Invalid\fR: Number of compilation tasks that were invalidated\&.+
−
+
−
\f3Time\fR: Time spent performing compilation tasks\&.+
−
+
−
\f3FailedType\fR: Compile type of the last failed compilation\&.+
−
+
−
\f3FailedMethod\fR: Class name and method of the last failed compilation\&.+
−
.TP+
−
-gc \fIoption\fR+
−
.br+
−
Garbage-collected heap statistics\&.+
−
+
−
\f3S0C\fR: Current survivor space 0 capacity (KB)\&.+
−
+
−
\f3S1C\fR: Current survivor space 1 capacity (KB)\&.+
−
+
−
\f3S0U\fR: Survivor space 0 utilization (KB)\&.+
−
+
−
\f3S1U\fR: Survivor space 1 utilization (KB)\&.+
−
+
−
\f3EC\fR: Current eden space capacity (KB)\&.+
−
+
−
\f3EU\fR: Eden space utilization (KB)\&.+
−
+
−
\f3OC\fR: Current old space capacity (KB)\&.+
−
+
−
\f3OU\fR: Old space utilization (KB)\&.+
−
+
−
\f3MC\fR: Metaspace capacity (KB)\&.+
−
+
−
\f3MU\fR: Metacspace utilization (KB)\&.+
−
+
−
\f3YGC\fR: Number of young generation garbage collection events\&.+
−
+
−
\f3YGCT\fR: Young generation garbage collection time\&.+
−
+
−
\f3FGC\fR: Number of full GC events\&.+
−
+
−
\f3FGCT\fR: Full garbage collection time\&.+
−
+
−
\f3GCT\fR: Total garbage collection time\&.+
−
.TP+
−
-gccapacity \fIoption\fR+
−
.br+
−
Memory pool generation and space capacities\&.+
−
+
−
\f3NGCMN\fR: Minimum new generation capacity (KB)\&.+
−
+
−
\f3NGCMX\fR: Maximum new generation capacity (KB)\&.+
−
+
−
\f3NGC\fR: Current new generation capacity (KB)\&.+
−
+
−
\f3S0C\fR: Current survivor space 0 capacity (KB)\&.+
−
+
−
\f3S1C\fR: Current survivor space 1 capacity (KB)\&.+
−
+
−
\f3EC\fR: Current eden space capacity (KB)\&.+
−
+
−
\f3OGCMN\fR: Minimum old generation capacity (KB)\&.+
−
+
−
\f3OGCMX\fR: Maximum old generation capacity (KB)\&.+
−
+
−
\f3OGC\fR: Current old generation capacity (KB)\&.+
−
+
−
\f3OC\fR: Current old space capacity (KB)\&.+
−
+
−
\f3MCMN\fR: Minimum metaspace capacity (KB)\&.+
−
+
−
\f3MCMX\fR: Maximum metaspace capacity (KB)\&.+
−
+
−
\f3MC\fR: Metaspace capacity (KB)\&.+
−
+
−
\f3YGC\fR: Number of Young generation GC Events\&.+
−
+
−
\f3FGC\fR: Number of Full GC Events\&.+
−
.TP+
−
-gccause \fIoption\fR+
−
.br+
−
This 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\&.+
−
+
−
Garbage collection statistics, including garbage collection Events\&.+
−
+
−
\f3LGCC\fR: Cause of last garbage collection\&.+
−
+
−
\f3GCC\fR: Cause of current garbage collection\&.+
−
.TP+
−
-gcnew \fIoption\fR+
−
.br+
−
New generation statistics\&.+
−
+
−
\f3S0C\fR: Current survivor space 0 capacity (KB)\&.+
−
+
−
\f3S1C\fR: Current survivor space 1 capacity (KB)\&.+
−
+
−
\f3S0U\fR: Survivor space 0 utilization (KB)\&.+
−
+
−
\f3S1U\fR: Survivor space 1 utilization (KB)\&.+
−
+
−
\f3TT\fR: Tenuring threshold\&.+
−
+
−
\f3MTT\fR: Maximum tenuring threshold\&.+
−
+
−
\f3DSS\fR: Desired survivor size (KB)\&.+
−
+
−
\f3EC\fR: Current eden space capacity (KB)\&.+
−
+
−
\f3EU\fR: Eden space utilization (KB)\&.+
−
+
−
\f3YGC\fR: Number of young generation GC events\&.+
−
+
−
\f3YGCT\fR: Young generation garbage collection time\&.+
−
.TP+
−
-gcnewcapacity \fIoption\fR+
−
.br+
−
New generation space size statistics\&.+
−
+
−
NGCMN: Minimum new generation capacity (KB)\&.+
−
+
−
\f3NGCMX\fR: Maximum new generation capacity (KB)\&.+
−
+
−
\f3NGC\fR: Current new generation capacity (KB)\&.+
−
+
−
\f3S0CMX\fR: Maximum survivor space 0 capacity (KB)\&.+
−
+
−
\f3S0C\fR: Current survivor space 0 capacity (KB)\&.+
−
+
−
\f3S1CMX\fR: Maximum survivor space 1 capacity (KB)\&.+
−
+
−
\f3S1C\fR: Current survivor space 1 capacity (KB)\&.+
−
+
−
\f3ECMX\fR: Maximum eden space capacity (KB)\&.+
−
+
−
\f3EC\fR: Current eden space capacity (KB)\&.+
−
+
−
\f3YGC\fR: Number of young generation GC events\&.+
−
+
−
\f3FGC\fR: Number of Full GC Events\&.+
−
.TP+
−
-gcold \fIoption\fR+
−
.br+
−
old and permanent generation statistics\&.+
−
+
−
\f3MC\fR: Metaspace capacity (KB)\&.+
−
+
−
\f3MU\fR: Metaspace utilization (KB)\&.+
−
+
−
\f3OC\fR: Current old space capacity (KB)\&.+
−
+
−
\f3OU\fR: old space utilization (KB)\&.+
−
+
−
\f3YGC\fR: Number of young generation GC events\&.+
−
+
−
\f3FGC\fR: Number of full GC events\&.+
−
+
−
\f3FGCT\fR: Full garbage collection time\&.+
−
+
−
\f3GCT\fR: Total garbage collection time\&.+
−
.TP+
−
-gcoldcapacity \fIoption\fR+
−
.br+
−
Old generation statistics\&.+
−
+
−
\f3OGCMN\fR: Minimum old generation capacity (KB)\&.+
−
+
−
\f3OGCMX\fR: Maximum old generation capacity (KB)\&.+
−
+
−
\f3OGC\fR: Current old generation capacity (KB)\&.+
−
+
−
\f3OC\fR: Current old space capacity (KB)\&.+
−
+
−
\f3YGC\fR: Number of young generation GC events\&.+
−
+
−
\f3FGC\fR: Number of full GC events\&.+
−
+
−
\f3FGCT\fR: Full garbage collection time\&.+
−
+
−
\f3GCT\fR: Total garbage collection time\&.+
−
.TP+
−
-gcmetacapacity \fIoption\fR+
−
.br+
−
Permanent generation statistics\&.+
−
+
−
\f3MCMN\fR: Minimum metaspace capacity (KB)\&.+
−
+
−
\f3MCMX\fR: Maximum metaspace capacity (KB)\&.+
−
+
−
\f3MC\fR: Metaspace capacity (KB)\&.+
−
+
−
\f3YGC\fR: Number of young generation GC events\&.+
−
+
−
\f3FGC\fR: Number of full GC events\&.+
−
+
−
\f3FGCT\fR: Full garbage collection time\&.+
−
+
−
\f3GCT\fR: Total garbage collection time\&.+
−
.TP+
−
-gcutil \fIoption\fR+
−
.br+
−
Summary of garbage collection statistics\&.+
−
+
−
\f3S0\fR: Survivor space 0 utilization as a percentage of the space\&'s current capacity\&.+
−
+
−
\f3S1\fR: Survivor space 1 utilization as a percentage of the space\&'s current capacity\&.+
−
+
−
\f3E\fR: Eden space utilization as a percentage of the space\&'s current capacity\&.+
−
+
−
\f3O\fR: Old space utilization as a percentage of the space\&'s current capacity\&.+
−
+
−
\f3M\fR: Metaspace utilization as a percentage of the space\&'s current capacity\&.+
−
+
−
\f3YGC\fR: Number of young generation GC events\&.+
−
+
−
\f3YGCT\fR: Young generation garbage collection time\&.+
−
+
−
\f3FGC\fR: Number of full GC events\&.+
−
+
−
\f3FGCT\fR: Full garbage collection time\&.+
−
+
−
\f3GCT\fR: Total garbage collection time\&.+
−
.TP+
−
-printcompilation \fIoption\fR+
−
.br+
−
Java HotSpot VM compiler method statistics\&.+
−
+
−
\f3Compiled\fR: Number of compilation tasks performed by the most recently compiled method\&.+
−
+
−
\f3Size\fR: Number of bytes of byte code of the most recently compiled method\&.+
−
+
−
\f3Type\fR: Compilation type of the most recently compiled method\&.+
−
+
−
\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:+PrintComplation\fR option\&.+
−
.SH EXAMPLES    +
−
This section presents some examples of monitoring a local JVM with an \fIlvmid\fR of 21891\&.+
−
.SS THE\ GCUTIL\ OPTION    +
−
This example attaches to lvmid 21891 and takes 7 samples at 250 millisecond intervals and displays the output as specified by the -\f3gcutil\fR option\&.+
−
.PP+
−
The output of this example shows that a young generation collection occurred between the third and fourth sample\&. The collection took 0\&.001 seconds and promoted objects from the eden space (E) to the old space (O), resulting in an increase of old space utilization from 9\&.49% to 9\&.51%\&. Before the collection, the survivor space was 12\&.44% utilized, but after this collection it is only 7\&.74% utilized\&.+
−
.sp     +
−
.nf     +
−
\f3jstat \-gcutil 21891 250 7\fP+
−
.fi     +
−
.nf     +
−
\f3  S0     S1     E      O      M       YGC    YGCT    FGC    FGCT     GCT\fP+
−
.fi     +
−
.nf     +
−
\f30\&.00  99\&.74  13\&.49   7\&.86  95\&.82      3    0\&.124     0    0\&.000    0\&.124\fP+
−
.fi     +
−
.nf     +
−
\f30\&.00  99\&.74  13\&.49   7\&.86  95\&.82      3    0\&.124     0    0\&.000    0\&.124\fP+
−
.fi     +
−
.nf     +
−
\f30\&.00  99\&.74  13\&.49   7\&.86  95\&.82      3    0\&.124     0    0\&.000    0\&.124\fP+
−
.fi     +
−
.nf     +
−
\f30\&.00  99\&.74  13\&.49   7\&.86  95\&.82      3    0\&.124     0    0\&.000    0\&.124\fP+
−
.fi     +
−
.nf     +
−
\f30\&.00  99\&.74  13\&.80   7\&.86  95\&.82      3    0\&.124     0    0\&.000    0\&.124\fP+
−
.fi     +
−
.nf     +
−
\f30\&.00  99\&.74  13\&.80   7\&.86  95\&.82      3    0\&.124     0    0\&.000    0\&.124\fP+
−
.fi     +
−
.nf     +
−
\f30\&.00  99\&.74  13\&.80   7\&.86  95\&.82      3    0\&.124     0    0\&.000    0\&.124\fP+
−
.fi     +
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.nf     +
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\f3\fP+
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.fi     +
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.sp     +
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.SS REPEAT\ THE\ COLUMN\ HEADER\ STRING    +
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This example attaches to lvmid 21891 and takes samples at 250 millisecond intervals and displays the output as specified by \f3-gcutil\fR option\&. In addition, it uses the \f3-h3\fR option to output the column header after every 3 lines of data\&.+
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.PP+
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In 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\&.+
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.PP+
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Another collection occurs between the fifth and sixth samples\&. This collection found very few survivors and returned the tenuring threshold to 31\&.+
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.sp     +
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.nf     +
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\f3jstat \-gcnew \-h3 21891 250\fP+
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.fi     +
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.nf     +
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\f3 S0C    S1C    S0U    S1U   TT MTT  DSS      EC       EU     YGC     YGCT\fP+
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.fi     +
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.nf     +
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\f3  64\&.0   64\&.0    0\&.0   31\&.7 31  31   32\&.0    512\&.0    178\&.6    249    0\&.203\fP+
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.fi     +
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.nf     +
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\f3  64\&.0   64\&.0    0\&.0   31\&.7 31  31   32\&.0    512\&.0    355\&.5    249    0\&.203\fP+
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.fi     +
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.nf     +
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\f3  64\&.0   64\&.0   35\&.4    0\&.0  2  31   32\&.0    512\&.0     21\&.9    250    0\&.204\fP+
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.fi     +
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.nf     +
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\f3 S0C    S1C    S0U    S1U   TT MTT  DSS      EC       EU     YGC     YGCT\fP+
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.fi     +
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.nf     +
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\f3  64\&.0   64\&.0   35\&.4    0\&.0  2  31   32\&.0    512\&.0    245\&.9    250    0\&.204\fP+
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.fi     +
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.nf     +
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\f3  64\&.0   64\&.0   35\&.4    0\&.0  2  31   32\&.0    512\&.0    421\&.1    250    0\&.204\fP+
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.fi     +
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.nf     +
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\f3  64\&.0   64\&.0    0\&.0   19\&.0 31  31   32\&.0    512\&.0     84\&.4    251    0\&.204\fP+
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.fi     +
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.nf     +
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\f3 S0C    S1C    S0U    S1U   TT MTT  DSS      EC       EU     YGC     YGCT\fP+
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.fi     +
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.nf     +
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\f3  64\&.0   64\&.0    0\&.0   19\&.0 31  31   32\&.0    512\&.0    306\&.7    251    0\&.204\fP+
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.fi     +
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.nf     +
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\f3\fP+
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.fi     +
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.sp     +
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.SS INCLUDE\ A\ TIME\ STAMP\ FOR\ EACH\ SAMPLE    +
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This 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\&.+
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.PP+
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The 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 to from 11,696 KB to 13820 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\&.+
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.sp     +
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.nf     +
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\f3Timestamp      OGCMN    OGCMX     OGC       OC       YGC   FGC    FGCT    GCT\fP+
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.fi     +
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.nf     +
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\f3          150\&.1   1408\&.0  60544\&.0  11696\&.0  11696\&.0   194    80    2\&.874   3\&.799\fP+
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.fi     +
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.nf     +
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\f3          150\&.4   1408\&.0  60544\&.0  13820\&.0  13820\&.0   194    81    2\&.938   3\&.863\fP+
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.fi     +
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.nf     +
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\f3          150\&.7   1408\&.0  60544\&.0  13820\&.0  13820\&.0   194    81    2\&.938   3\&.863\fP+
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.fi     +
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.nf     +
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\f3\fP+
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.fi     +
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.sp     +
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.SS MONITOR\ INSTRUMENTATION\ FOR\ A\ REMOTE\ JVM    +
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This example attaches to lvmid 40496 on the system named remote\&.domain using the \f3-gcutil\fR option, with samples taken every second indefinitely\&.+
−
.PP+
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The 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 rmiregistry on \f3remote\&.domain\fR that is bound to the default rmiregistry port (port 1099)\&.+
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.sp     +
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.nf     +
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\f3jstat \-gcutil 40496@remote\&.domain 1000\fP+
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.fi     +
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.nf     +
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\f3\fI\&.\&.\&. output omitted\fR\fP+
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.fi     +
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.nf     +
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\f3\fP+
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.fi     +
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.sp     +
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.SH SEE\ ALSO    +
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.TP 0.2i    +
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\(bu+
−
java(1)+
−
.TP 0.2i    +
−
\(bu+
−
jps(1)+
−
.TP 0.2i    +
−
\(bu+
−
jstatd(1)+
−
.TP 0.2i    +
−
\(bu+
−
rmiregistry(1)+
−
.RE+
−
.br+
−
'pl 8.5i+
−
'bp+
−