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'\" t
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.\" Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved.
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.\"
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.\" DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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.\"
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.\" This code is free software; you can redistribute it and/or modify it
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.\" under the terms of the GNU General Public License version 2 only, as
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.\" published by the Free Software Foundation.
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.\"
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.\" This code is distributed in the hope that it will be useful, but WITHOUT
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.\" ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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.\" FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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.\" version 2 for more details (a copy is included in the LICENSE file that
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.\" accompanied this code).
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.\"
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.\" You should have received a copy of the GNU General Public License version
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.\" 2 along with this work; if not, write to the Free Software Foundation,
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.\" Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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.\"
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.\" Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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.\" or visit www.oracle.com if you need additional information or have any
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.\" questions.
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.\"
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.\" Arch: generic
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.\" Software: JDK 8
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.\" Date: 10 May 2011
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.\" SectDesc: Monitoring Tools
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.\" Title: jstat.1
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.\"
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.if n .pl 99999
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.TH jstat 1 "10 May 2011" "JDK 8" "Monitoring Tools"
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.\" -----------------------------------------------------------------
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.\" * Define some portability stuff
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.\" -----------------------------------------------------------------
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.\" http://bugs.debian.org/507673
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.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.ie \n(.g .ds Aq \(aq
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.el .ds Aq '
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.\" -----------------------------------------------------------------
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.\" * set default formatting
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.\" -----------------------------------------------------------------
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.\" disable hyphenation
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.\" disable justification (adjust text to left margin only)
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.ad l
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.\" -----------------------------------------------------------------
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.\" * MAIN CONTENT STARTS HERE *
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.\" -----------------------------------------------------------------
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.SH NAME
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jstat \- Monitors Java Virtual Machine (JVM) statistics\&. This command is experimental and unsupported\&.
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.SH SYNOPSIS
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.sp
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.nf
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\fBjstat\fR [ \fIgeneralOption\fR | \fIoutputOptions vmid\fR [ \fIinterval\fR[s|ms] [ \fIcount \fR] ]
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.fi
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.sp
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.TP
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\fIgeneralOption\fR
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A single general command-line option \f3-help\fR or \f3-options\fR\&. See General Options\&.
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.TP
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\fIoutputOptions\fR
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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\&.
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.TP
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\fIvmid\fR
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Virtual machine identifier, which is a string that indicates the target JVM\&. The general syntax is the following:
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.sp
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.nf
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\f3[protocol:][//]lvmid[@hostname[:port]/servername]\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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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\&.
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.TP
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\fIinterval\fR [s|ms]
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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\&.
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.TP
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\fIcount\fR
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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\&.
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.SH DESCRIPTION
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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\&.
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.SH VIRTUAL\ MACHINE\ IDENTIFIER
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The syntax of the \f3vmid\fR string corresponds to the syntax of a URI:
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.sp
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.nf
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\f3[protocol:][//]lvmid[@hostname[:port]/servername]\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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.TP
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\fIprotocol\fR
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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\&.
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.TP
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\fIlvmid\fR
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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\&.
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.TP
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\fIhostname\fR
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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\&.
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.TP
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\fIport\fR
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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\&.
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.TP
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\fIservername\fR
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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\&.
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.SH OPTIONS
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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\&.
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.PP
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All options and their functionality are subject to change or removal in future releases\&.
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.SS GENERAL\ OPTIONS
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If you specify one of the general options, then you cannot specify any other option or parameter\&.
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.TP
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-help
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2
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.br
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Displays a help message\&.
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.TP
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-options
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.br
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Displays a list of static options\&. See Output Options\&.
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.SS OUTPUT\ OPTIONS
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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\&.
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.PP
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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\&.
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.PP
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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\&.
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.PP
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Use the interval and count parameters to determine how frequently and how many times, respectively, the \f3jstat\fR command displays its output\&.
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.PP
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\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\&.
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.TP
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-\fIstatOption\fR
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.br
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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\&.
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\f3class\fR: Displays statistics about the behavior of the class loader\&.
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\f3compiler\fR: Displays statistics about the behavior of the Java HotSpot VM Just-in-Time compiler\&.
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\f3gc\fR: Displays statistics about the behavior of the garbage collected heap\&.
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\f3gccapacity\fR: Displays statistics about the capacities of the generations and their corresponding spaces\&.
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\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\&.
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\f3gcnew\fR: Displays statistics of the behavior of the new generation\&.
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\f3gcnewcapacity\fR: Displays statistics about the sizes of the new generations and its corresponding spaces\&.
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\f3gcold\fR: Displays statistics about the behavior of the old generation and Metaspace Statistics\&.
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\f3gcoldcapacity\fR: Displays statistics about the sizes of the old generation\&.
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\f3gcmetacapacity\fR: Displays statistics about the sizes of the metaspace\&.
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\f3gcutil\fR: Displays a summary about garbage collection statistics\&.
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\f3printcompilation\fR: Displays Java HotSpot VM compilation method statistics\&.
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.TP
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-h \fIn\fR
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2
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.br
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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\&.
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.TP
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-t
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.br
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Display sa timestamp column as the first column of output\&. The time stamp is the time since the start time of the target JVM\&.
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.TP
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-J\fIjavaOption\fR
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.br
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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)\&.
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.SS STAT\ OPTIONS\ AND\ OUTPUT
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The following information summarizes the columns that the \f3jstat\fR command outputs for each \fIstatOption\fR\&.
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.TP
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-class \fIoption\fR
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.br
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Class loader statistics\&.
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\f3Loaded\fR: Number of classes loaded\&.
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\f3Bytes\fR: Number of KBs loaded\&.
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\f3Unloaded\fR: Number of classes unloaded\&.
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\f3Bytes\fR: Number of Kbytes unloaded\&.
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\f3Time\fR: Time spent performing class loading and unloading operations\&.
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.TP
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-compiler \fIoption\fR
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2
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.br
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Java HotSpot VM Just-in-Time compiler statistics\&.
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\f3Compiled\fR: Number of compilation tasks performed\&.
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\f3Failed\fR: Number of compilations tasks failed\&.
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\f3Invalid\fR: Number of compilation tasks that were invalidated\&.
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\f3Time\fR: Time spent performing compilation tasks\&.
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\f3FailedType\fR: Compile type of the last failed compilation\&.
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\f3FailedMethod\fR: Class name and method of the last failed compilation\&.
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.TP
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-gc \fIoption\fR
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2
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.br
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Garbage-collected heap statistics\&.
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\f3S0C\fR: Current survivor space 0 capacity (KB)\&.
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\f3S1C\fR: Current survivor space 1 capacity (KB)\&.
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\f3S0U\fR: Survivor space 0 utilization (KB)\&.
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\f3S1U\fR: Survivor space 1 utilization (KB)\&.
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\f3EC\fR: Current eden space capacity (KB)\&.
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\f3EU\fR: Eden space utilization (KB)\&.
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\f3OC\fR: Current old space capacity (KB)\&.
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\f3OU\fR: Old space utilization (KB)\&.
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\f3MC\fR: Metaspace capacity (KB)\&.
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\f3MU\fR: Metacspace utilization (KB)\&.
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\f3YGC\fR: Number of young generation garbage collection events\&.
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\f3YGCT\fR: Young generation garbage collection time\&.
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\f3FGC\fR: Number of full GC events\&.
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\f3FGCT\fR: Full garbage collection time\&.
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\f3GCT\fR: Total garbage collection time\&.
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.TP
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245 |
-gccapacity \fIoption\fR
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2
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.br
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Memory pool generation and space capacities\&.
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\f3NGCMN\fR: Minimum new generation capacity (KB)\&.
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\f3NGCMX\fR: Maximum new generation capacity (KB)\&.
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\f3NGC\fR: Current new generation capacity (KB)\&.
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\f3S0C\fR: Current survivor space 0 capacity (KB)\&.
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\f3S1C\fR: Current survivor space 1 capacity (KB)\&.
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\f3EC\fR: Current eden space capacity (KB)\&.
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\f3OGCMN\fR: Minimum old generation capacity (KB)\&.
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\f3OGCMX\fR: Maximum old generation capacity (KB)\&.
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\f3OGC\fR: Current old generation capacity (KB)\&.
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\f3OC\fR: Current old space capacity (KB)\&.
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\f3MCMN\fR: Minimum metaspace capacity (KB)\&.
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\f3MCMX\fR: Maximum metaspace capacity (KB)\&.
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\f3MC\fR: Metaspace capacity (KB)\&.
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\f3YGC\fR: Number of Young generation GC Events\&.
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\f3FGC\fR: Number of Full GC Events\&.
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.TP
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-gccause \fIoption\fR
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2
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.br
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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\&.
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282 |
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283 |
Garbage collection statistics, including garbage collection Events\&.
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\f3LGCC\fR: Cause of last garbage collection\&.
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\f3GCC\fR: Cause of current garbage collection\&.
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.TP
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-gcnew \fIoption\fR
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2
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290 |
.br
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21743
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New generation statistics\&.
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\f3S0C\fR: Current survivor space 0 capacity (KB)\&.
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\f3S1C\fR: Current survivor space 1 capacity (KB)\&.
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\f3S0U\fR: Survivor space 0 utilization (KB)\&.
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\f3S1U\fR: Survivor space 1 utilization (KB)\&.
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\f3TT\fR: Tenuring threshold\&.
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|
303 |
\f3MTT\fR: Maximum tenuring threshold\&.
|
|
|
304 |
|
|
|
305 |
\f3DSS\fR: Desired survivor size (KB)\&.
|
|
|
306 |
|
|
|
307 |
\f3EC\fR: Current eden space capacity (KB)\&.
|
|
|
308 |
|
|
|
309 |
\f3EU\fR: Eden space utilization (KB)\&.
|
|
|
310 |
|
|
|
311 |
\f3YGC\fR: Number of young generation GC events\&.
|
|
2692
|
312 |
|
|
21743
|
313 |
\f3YGCT\fR: Young generation garbage collection time\&.
|
|
|
314 |
.TP
|
|
|
315 |
-gcnewcapacity \fIoption\fR
|
|
2
|
316 |
.br
|
|
21743
|
317 |
New generation space size statistics\&.
|
|
|
318 |
|
|
|
319 |
NGCMN: Minimum new generation capacity (KB)\&.
|
|
|
320 |
|
|
|
321 |
\f3NGCMX\fR: Maximum new generation capacity (KB)\&.
|
|
|
322 |
|
|
|
323 |
\f3NGC\fR: Current new generation capacity (KB)\&.
|
|
|
324 |
|
|
|
325 |
\f3S0CMX\fR: Maximum survivor space 0 capacity (KB)\&.
|
|
|
326 |
|
|
|
327 |
\f3S0C\fR: Current survivor space 0 capacity (KB)\&.
|
|
|
328 |
|
|
|
329 |
\f3S1CMX\fR: Maximum survivor space 1 capacity (KB)\&.
|
|
|
330 |
|
|
|
331 |
\f3S1C\fR: Current survivor space 1 capacity (KB)\&.
|
|
|
332 |
|
|
|
333 |
\f3ECMX\fR: Maximum eden space capacity (KB)\&.
|
|
|
334 |
|
|
|
335 |
\f3EC\fR: Current eden space capacity (KB)\&.
|
|
|
336 |
|
|
|
337 |
\f3YGC\fR: Number of young generation GC events\&.
|
|
|
338 |
|
|
|
339 |
\f3FGC\fR: Number of Full GC Events\&.
|
|
|
340 |
.TP
|
|
|
341 |
-gcold \fIoption\fR
|
|
2
|
342 |
.br
|
|
21743
|
343 |
old and permanent generation statistics\&.
|
|
|
344 |
|
|
|
345 |
\f3MC\fR: Metaspace capacity (KB)\&.
|
|
|
346 |
|
|
|
347 |
\f3MU\fR: Metaspace utilization (KB)\&.
|
|
|
348 |
|
|
|
349 |
\f3OC\fR: Current old space capacity (KB)\&.
|
|
|
350 |
|
|
|
351 |
\f3OU\fR: old space utilization (KB)\&.
|
|
|
352 |
|
|
|
353 |
\f3YGC\fR: Number of young generation GC events\&.
|
|
|
354 |
|
|
|
355 |
\f3FGC\fR: Number of full GC events\&.
|
|
|
356 |
|
|
|
357 |
\f3FGCT\fR: Full garbage collection time\&.
|
|
2692
|
358 |
|
|
21743
|
359 |
\f3GCT\fR: Total garbage collection time\&.
|
|
|
360 |
.TP
|
|
|
361 |
-gcoldcapacity \fIoption\fR
|
|
2
|
362 |
.br
|
|
21743
|
363 |
Old generation statistics\&.
|
|
|
364 |
|
|
|
365 |
\f3OGCMN\fR: Minimum old generation capacity (KB)\&.
|
|
|
366 |
|
|
|
367 |
\f3OGCMX\fR: Maximum old generation capacity (KB)\&.
|
|
|
368 |
|
|
|
369 |
\f3OGC\fR: Current old generation capacity (KB)\&.
|
|
|
370 |
|
|
|
371 |
\f3OC\fR: Current old space capacity (KB)\&.
|
|
|
372 |
|
|
|
373 |
\f3YGC\fR: Number of young generation GC events\&.
|
|
|
374 |
|
|
|
375 |
\f3FGC\fR: Number of full GC events\&.
|
|
|
376 |
|
|
|
377 |
\f3FGCT\fR: Full garbage collection time\&.
|
|
|
378 |
|
|
|
379 |
\f3GCT\fR: Total garbage collection time\&.
|
|
|
380 |
.TP
|
|
|
381 |
-gcmetacapacity \fIoption\fR
|
|
2
|
382 |
.br
|
|
21743
|
383 |
Permanent generation statistics\&.
|
|
|
384 |
|
|
|
385 |
\f3MCMN\fR: Minimum metaspace capacity (KB)\&.
|
|
|
386 |
|
|
|
387 |
\f3MCMX\fR: Maximum metaspace capacity (KB)\&.
|
|
|
388 |
|
|
|
389 |
\f3MC\fR: Metaspace capacity (KB)\&.
|
|
|
390 |
|
|
|
391 |
\f3YGC\fR: Number of young generation GC events\&.
|
|
|
392 |
|
|
|
393 |
\f3FGC\fR: Number of full GC events\&.
|
|
|
394 |
|
|
|
395 |
\f3FGCT\fR: Full garbage collection time\&.
|
|
|
396 |
|
|
|
397 |
\f3GCT\fR: Total garbage collection time\&.
|
|
|
398 |
.TP
|
|
|
399 |
-gcutil \fIoption\fR
|
|
2
|
400 |
.br
|
|
21743
|
401 |
Summary of garbage collection statistics\&.
|
|
|
402 |
|
|
|
403 |
\f3S0\fR: Survivor space 0 utilization as a percentage of the space\&'s current capacity\&.
|
|
|
404 |
|
|
|
405 |
\f3S1\fR: Survivor space 1 utilization as a percentage of the space\&'s current capacity\&.
|
|
|
406 |
|
|
|
407 |
\f3E\fR: Eden space utilization as a percentage of the space\&'s current capacity\&.
|
|
|
408 |
|
|
|
409 |
\f3O\fR: Old space utilization as a percentage of the space\&'s current capacity\&.
|
|
|
410 |
|
|
|
411 |
\f3M\fR: Metaspace utilization as a percentage of the space\&'s current capacity\&.
|
|
2692
|
412 |
|
|
21743
|
413 |
\f3YGC\fR: Number of young generation GC events\&.
|
|
|
414 |
|
|
|
415 |
\f3YGCT\fR: Young generation garbage collection time\&.
|
|
|
416 |
|
|
|
417 |
\f3FGC\fR: Number of full GC events\&.
|
|
|
418 |
|
|
|
419 |
\f3FGCT\fR: Full garbage collection time\&.
|
|
|
420 |
|
|
|
421 |
\f3GCT\fR: Total garbage collection time\&.
|
|
|
422 |
.TP
|
|
|
423 |
-printcompilation \fIoption\fR
|
|
2
|
424 |
.br
|
|
21743
|
425 |
Java HotSpot VM compiler method statistics\&.
|
|
|
426 |
|
|
|
427 |
\f3Compiled\fR: Number of compilation tasks performed by the most recently compiled method\&.
|
|
2692
|
428 |
|
|
21743
|
429 |
\f3Size\fR: Number of bytes of byte code of the most recently compiled method\&.
|
|
|
430 |
|
|
|
431 |
\f3Type\fR: Compilation type of the most recently compiled method\&.
|
|
2692
|
432 |
|
|
21743
|
433 |
\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\&.
|
|
|
434 |
.SH EXAMPLES
|
|
|
435 |
This section presents some examples of monitoring a local JVM with an \fIlvmid\fR of 21891\&.
|
|
|
436 |
.SS THE\ GCUTIL\ OPTION
|
|
|
437 |
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\&.
|
|
|
438 |
.PP
|
|
|
439 |
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\&.
|
|
|
440 |
.sp
|
|
|
441 |
.nf
|
|
|
442 |
\f3jstat \-gcutil 21891 250 7\fP
|
|
|
443 |
.fi
|
|
|
444 |
.nf
|
|
|
445 |
\f3 S0 S1 E O M YGC YGCT FGC FGCT GCT\fP
|
|
|
446 |
.fi
|
|
|
447 |
.nf
|
|
|
448 |
\f30\&.00 99\&.74 13\&.49 7\&.86 95\&.82 3 0\&.124 0 0\&.000 0\&.124\fP
|
|
|
449 |
.fi
|
|
|
450 |
.nf
|
|
|
451 |
\f30\&.00 99\&.74 13\&.49 7\&.86 95\&.82 3 0\&.124 0 0\&.000 0\&.124\fP
|
|
|
452 |
.fi
|
|
|
453 |
.nf
|
|
|
454 |
\f30\&.00 99\&.74 13\&.49 7\&.86 95\&.82 3 0\&.124 0 0\&.000 0\&.124\fP
|
|
|
455 |
.fi
|
|
|
456 |
.nf
|
|
|
457 |
\f30\&.00 99\&.74 13\&.49 7\&.86 95\&.82 3 0\&.124 0 0\&.000 0\&.124\fP
|
|
|
458 |
.fi
|
|
|
459 |
.nf
|
|
|
460 |
\f30\&.00 99\&.74 13\&.80 7\&.86 95\&.82 3 0\&.124 0 0\&.000 0\&.124\fP
|
|
|
461 |
.fi
|
|
|
462 |
.nf
|
|
|
463 |
\f30\&.00 99\&.74 13\&.80 7\&.86 95\&.82 3 0\&.124 0 0\&.000 0\&.124\fP
|
|
|
464 |
.fi
|
|
|
465 |
.nf
|
|
|
466 |
\f30\&.00 99\&.74 13\&.80 7\&.86 95\&.82 3 0\&.124 0 0\&.000 0\&.124\fP
|
|
|
467 |
.fi
|
|
|
468 |
.nf
|
|
|
469 |
\f3\fP
|
|
|
470 |
.fi
|
|
|
471 |
.sp
|
|
|
472 |
.SS REPEAT\ THE\ COLUMN\ HEADER\ STRING
|
|
|
473 |
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\&.
|
|
|
474 |
.PP
|
|
|
475 |
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\&.
|
|
|
476 |
.PP
|
|
|
477 |
Another collection occurs between the fifth and sixth samples\&. This collection found very few survivors and returned the tenuring threshold to 31\&.
|
|
|
478 |
.sp
|
|
|
479 |
.nf
|
|
|
480 |
\f3jstat \-gcnew \-h3 21891 250\fP
|
|
|
481 |
.fi
|
|
|
482 |
.nf
|
|
|
483 |
\f3 S0C S1C S0U S1U TT MTT DSS EC EU YGC YGCT\fP
|
|
|
484 |
.fi
|
|
|
485 |
.nf
|
|
|
486 |
\f3 64\&.0 64\&.0 0\&.0 31\&.7 31 31 32\&.0 512\&.0 178\&.6 249 0\&.203\fP
|
|
|
487 |
.fi
|
|
|
488 |
.nf
|
|
|
489 |
\f3 64\&.0 64\&.0 0\&.0 31\&.7 31 31 32\&.0 512\&.0 355\&.5 249 0\&.203\fP
|
|
|
490 |
.fi
|
|
|
491 |
.nf
|
|
|
492 |
\f3 64\&.0 64\&.0 35\&.4 0\&.0 2 31 32\&.0 512\&.0 21\&.9 250 0\&.204\fP
|
|
|
493 |
.fi
|
|
|
494 |
.nf
|
|
|
495 |
\f3 S0C S1C S0U S1U TT MTT DSS EC EU YGC YGCT\fP
|
|
|
496 |
.fi
|
|
|
497 |
.nf
|
|
|
498 |
\f3 64\&.0 64\&.0 35\&.4 0\&.0 2 31 32\&.0 512\&.0 245\&.9 250 0\&.204\fP
|
|
|
499 |
.fi
|
|
|
500 |
.nf
|
|
|
501 |
\f3 64\&.0 64\&.0 35\&.4 0\&.0 2 31 32\&.0 512\&.0 421\&.1 250 0\&.204\fP
|
|
|
502 |
.fi
|
|
|
503 |
.nf
|
|
|
504 |
\f3 64\&.0 64\&.0 0\&.0 19\&.0 31 31 32\&.0 512\&.0 84\&.4 251 0\&.204\fP
|
|
|
505 |
.fi
|
|
|
506 |
.nf
|
|
|
507 |
\f3 S0C S1C S0U S1U TT MTT DSS EC EU YGC YGCT\fP
|
|
|
508 |
.fi
|
|
|
509 |
.nf
|
|
|
510 |
\f3 64\&.0 64\&.0 0\&.0 19\&.0 31 31 32\&.0 512\&.0 306\&.7 251 0\&.204\fP
|
|
|
511 |
.fi
|
|
|
512 |
.nf
|
|
|
513 |
\f3\fP
|
|
|
514 |
.fi
|
|
|
515 |
.sp
|
|
|
516 |
.SS INCLUDE\ A\ TIME\ STAMP\ FOR\ EACH\ SAMPLE
|
|
|
517 |
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\&.
|
|
|
518 |
.PP
|
|
|
519 |
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\&.
|
|
|
520 |
.sp
|
|
|
521 |
.nf
|
|
|
522 |
\f3Timestamp OGCMN OGCMX OGC OC YGC FGC FGCT GCT\fP
|
|
|
523 |
.fi
|
|
|
524 |
.nf
|
|
|
525 |
\f3 150\&.1 1408\&.0 60544\&.0 11696\&.0 11696\&.0 194 80 2\&.874 3\&.799\fP
|
|
|
526 |
.fi
|
|
|
527 |
.nf
|
|
|
528 |
\f3 150\&.4 1408\&.0 60544\&.0 13820\&.0 13820\&.0 194 81 2\&.938 3\&.863\fP
|
|
|
529 |
.fi
|
|
|
530 |
.nf
|
|
|
531 |
\f3 150\&.7 1408\&.0 60544\&.0 13820\&.0 13820\&.0 194 81 2\&.938 3\&.863\fP
|
|
|
532 |
.fi
|
|
|
533 |
.nf
|
|
|
534 |
\f3\fP
|
|
|
535 |
.fi
|
|
|
536 |
.sp
|
|
|
537 |
.SS MONITOR\ INSTRUMENTATION\ FOR\ A\ REMOTE\ JVM
|
|
|
538 |
This example attaches to lvmid 40496 on the system named remote\&.domain using the \f3-gcutil\fR option, with samples taken every second indefinitely\&.
|
|
|
539 |
.PP
|
|
|
540 |
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)\&.
|
|
|
541 |
.sp
|
|
|
542 |
.nf
|
|
|
543 |
\f3jstat \-gcutil 40496@remote\&.domain 1000\fP
|
|
|
544 |
.fi
|
|
|
545 |
.nf
|
|
|
546 |
\f3\fI\&.\&.\&. output omitted\fR\fP
|
|
|
547 |
.fi
|
|
|
548 |
.nf
|
|
|
549 |
\f3\fP
|
|
|
550 |
.fi
|
|
|
551 |
.sp
|
|
|
552 |
.SH SEE\ ALSO
|
|
|
553 |
.TP 0.2i
|
|
|
554 |
\(bu
|
|
|
555 |
java(1)
|
|
|
556 |
.TP 0.2i
|
|
|
557 |
\(bu
|
|
|
558 |
jps(1)
|
|
|
559 |
.TP 0.2i
|
|
|
560 |
\(bu
|
|
|
561 |
jstatd(1)
|
|
|
562 |
.TP 0.2i
|
|
|
563 |
\(bu
|
|
|
564 |
rmiregistry(1)
|
|
|
565 |
.RE
|
|
|
566 |
.br
|
|
|
567 |
'pl 8.5i
|
|
|
568 |
'bp
|