jstat man page on Ubuntu

Man page or keyword search:  
man Server   6591 pages
apropos Keyword Search (all sections)
Output format
Ubuntu logo
[printable version]

jstat(1)							      jstat(1)

NAME
       jstat - Java Virtual Machine Statistics Monitoring Tool

SYNOPSIS
       jstat [ generalOption | outputOptionsvmid [interval[s|ms] [count]] ]

PARAMETERS
       generalOption
	  A single general command-line option (-help, -options, or -version)

       outputOptions
	  One  or more output options, consisting of a single statOption, plus
	  any of the -t, -h, and -J options.

       vmid
	  Virtual machine identifier, a string indicating the target Java vir‐
	  tual machine (JVM). The general syntax is
	  [protocol:][//]lvmid[@hostname[:port]/servername]
	  The syntax of the vmid string largely corresponds to the syntax of a
	  URI. The vmid can vary from a simple integer	representing  a	 local
	  JVM  to a more complex construction specifying a communications pro‐
	  tocol, port number, and other	 implementation-specific  values.  See
	  Virtual Machine Identifier for details.

       interval[s|ms]
	  Sampling  interval  in the specified units, seconds (s) or millisec‐
	  onds (ms). Default units are milliseconds.  Must be a positive inte‐
	  ger.	If specified, jstat will produce its output at each interval.

       count
	  Number  of  samples  to display. Default value is infinity; that is,
	  jstat displays statistics until the target  JVM  terminates  or  the
	  jstat command is terminated.	Must be a positive integer.

DESCRIPTION
       The  jstat  tool	 displays  performance	statistics for an instrumented
       HotSpot Java virtual machine (JVM). The target JVM is identified by its
       virtual machine identifier, or vmid option described below.

       NOTE:  This  utility  is unsupported and may not be available in future
       versions of the JDK. It is not currently available on  Windows  98  and
       Windows ME. platforms.

   VIRTUAL MACHINE IDENTIFIER
       The  syntax  of	the vmid string largely corresponds to the syntax of a
       URI:
       [protocol:][//]lvmid[@hostname][:port][/servername]

       protocol
	  The communications protocol. If the protocol is omitted and a	 host‐
	  name	is  not specified, the default protocol is a platform specific
	  optimized local protocol. If the protocol is omitted and a  hostname
	  is specified, then the default protocol is rmi.

       lvmid
	  The  local  virtual machine identifier for the target JVM. The lvmid
	  is a platform-specific value that uniquely identifies	 a  JVM	 on  a
	  system.  The	lvmid  is  the	only  required	component of a virtual
	  machine identifier. The lvmid is typically, but not necessarily, the
	  operating  system's  process	identifier for the target JVM process.
	  You can use the jps command to determine the lvmid.  Also,  you  can
	  determine  lvmid  on Unix platforms with the ps command, and on Win‐
	  dows with the Windows Task Manager.

       hostname
	  A hostname or IP address indicating the target host. If hostname  is
	  omitted, then the target host is the local host.

       port
	  The  default	port  for communicating with the remote server. If the
	  hostname is omitted or the protocol specifies	 an  optimized,	 local
	  protocol,  then  port	 is  ignored. Otherwise, treatment of the port
	  parameter is implementation specific. For the default rmi  protocol,
	  the port indicates the port number for the rmiregistry on the remote
	  host. If port is omitted,  and  protocol  indicates  rmi,  then  the
	  default rmiregistry port (1099) is used.

       servername
	  The  treatment  of this parameter depends on implementation. For the
	  optimized local protocol, this field is ignored. For the rmi	proto‐
	  col,	it  represents the name of the RMI remote object on the remote
	  host.

OPTIONS
       The jstat command supports two types of options,	 general  options  and
       output options. General options cause jstat to display simple usage and
       version information. Output options determine the content and format of
       the statistical output.

       NOTE:  All  options,  and  their functionality are subject to change or
       removal in future releases.

   GENERAL
       OPTIONS

       If you specify one of the general options, you cannot specify any other
       option or parameter.

       -help
	  Display help message.

       -version
	  Display version information.

       -options
	  Display  list	 of statistics options. See the Output Options section
	  below.

   OUTPUT
       OPTIONS

       If you do not specify a general option, then  you  can  specify	output
       options.	 Output	 options  determine  the content and format of jstat's
       output, and consist of a single statOption, plus any of the other  out‐
       put options (-h, -t, and -J).  The statOption must come first.

       Output is formatted as a table, with columns are separated by spaces. A
       header row with titles describes the columns.  Use the -h option to set
       the  frequency  at  which the header is displayed.  Column header names
       are generally consistent between the different options. In general,  if
       two  options  provide a column with the same name, then the data source
       for the two columns are the same.

       Use the -t 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 startup of the target JVM.  The	resolution  of
       the time stamp is dependent on various factors and is subject to varia‐
       tion due to delayed thread scheduling on heavily loaded systems.

       Use the interval and count parameters to determine how  frequently  and
       how many times, respectively, jstat displays its output.

       NOTE:  You  are	advised	 not  to write scripts to parse jstat's output
       since the format may change in future releases. If you choose to	 write
       scripts	that  parse  jstat  output,  expect  to modify them for future
       releases of this tool.

       -statOption
	  Determines the statistics information that jstat displays. The  fol‐
	  lowing  table lists the available options.  Use the -options general
	  option to display the list of	 options  for  a  particular  platform
	  installation.

       -hn
	  Display  a column header every n samples (output rows), where n is a
	  positive integer. Default value is  0,  which	 displays  the	column
	  header above the first row of data.

       -tn
	  Display  a timestamp column as the first column of output. The time‐
	  stamp is the the time since the start time of the target JVM.

       -JjavaOption
	  Pass javaOption to  the  java	 application  launcher.	 For  example,
	  -J-Xms48m  sets  the	startup memory to 48 megabytes. For a complete
	  list of options, see the following documents:

	  * java - the Java application launcher (Solaris) @
	    http://java.sun.com/javase/6/docs/tech‐
	    notes/tools/solaris/java.html

	  * java - the Java application launcher (Linux) @
	    http://java.sun.com/javase/6/docs/technotes/tools/linux/java.html

	  * java - the Java application launcher (Windows)

   STATOPTIONS AND
       OUTPUT

       The following tables summarize the columns that jstat outputs for each
       statOption.

   -class Option
   -compiler
       Option

   -gc Option
   -gccapacity Option
   -gccause
       Option

       This option displays the same summary of garbage collection statistics
       as the -gcutil option, but includes the causes of the last garbage col‐
       lection event and (if applicable) the current garbage collection event.
       In addition to the columns listed for -gcutil, this option adds the
       following columns:

   -gcnew Option
   -gcnewcapacity Option
   -gcold Option
   -gcoldcapacity Option
   -gcpermcapacity Option
   -gcutil
       Option

   -printcompilation Option

       This section presents some examples of monitoring a local JVM with a
       lvmid of 21891.

   Using the gcutil option
       This example attaches to lvmid 21891 and takes 7 samples at 250 mil‐
       lisecond intervals and displays the output as specified by the -gcutil
       option.
       jstat -gcutil 21891 250 7

	 S0	S1     E      O	     P	   YGC	  YGCT	  FGC	 FGCT	  GCT

	12.44	0.00  27.20   9.49  96.70    78	   0.176     5	  0.495	   0.672

	12.44	0.00  62.16   9.49  96.70    78	   0.176     5	  0.495	   0.672

	12.44	0.00  83.97   9.49  96.70    78	   0.176     5	  0.495	   0.672

	 0.00	7.74   0.00   9.51  96.70    79	   0.177     5	  0.495	   0.673

	 0.00	7.74  23.37   9.51  96.70    79	   0.177     5	  0.495	   0.673

	 0.00	7.74  43.82   9.51  96.70    79	   0.177     5	  0.495	   0.673

	 0.00	7.74  58.11   9.51  96.71    79	   0.177     5	  0.495	   0.673

       The output of this example shows that a young generation collection
       occurred between the 3rd and 4th sample. The collection took 0.001 sec‐
       onds 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.

   Repeating the column header
       string

       This example attaches to lvmid 21891 and takes samples at 250 millisec‐
       ond intervals and displays the output as specified by -gcutil option.
       In addition, it uses the -h3 option to output the column header after
       every 3 lines of data.
       jstat -gcnew -h3 21891 250

	S0C    S1C    S0U    S1U   TT MTT  DSS	    EC	     EU	    YGC	    YGCT

	 64.0	64.0	0.0   31.7 31  31   32.0    512.0    178.6    249    0.203

	 64.0	64.0	0.0   31.7 31  31   32.0    512.0    355.5    249    0.203

	 64.0	64.0   35.4    0.0  2  31   32.0    512.0     21.9    250    0.204

	S0C    S1C    S0U    S1U   TT MTT  DSS	    EC	     EU	    YGC	    YGCT

	 64.0	64.0   35.4    0.0  2  31   32.0    512.0    245.9    250    0.204

	 64.0	64.0   35.4    0.0  2  31   32.0    512.0    421.1    250    0.204

	 64.0	64.0	0.0   19.0 31  31   32.0    512.0     84.4    251    0.204

	S0C    S1C    S0U    S1U   TT MTT  DSS	    EC	     EU	    YGC	    YGCT

	 64.0	64.0	0.0   19.0 31  31   32.0    512.0    306.7    251    0.204

       In addition to showing the repeating header string, this example shows
       that between the 2nd and 3rd samples, a young GC occurred. Its duration
       was 0.001 seconds. The collection found enough live data that the sur‐
       vivor space 0 utilization (S0U) would would have exceeded the desired
       survivor Size (DSS). As a result, objects were promoted to the old gen‐
       eration (not visible in this output), and the tenuring threshold (TT)
       was lowered from 31 to 2.

       Another collection occurs between the 5th and 6th samples. This collec‐
       tion found very few survivors and returned the tenuring threshold to
       31.

   Including a
       time stamp for each sample

       This example attaches to lvmid 21891 and takes 3 samples at 250 mil‐
       lisecond intervals. The -t option is used to generate a time stamp for
       each sample in the first column.
       jstat -gcoldcapacity -t 21891 250 3

       Timestamp	  OGCMN	       OGCMX	     OGC	   OC	    YGC	  FGC	 FGCT	 GCT

		 150.1	     1408.0	 60544.0      11696.0	   11696.0   194    80	  2.874	  3.799

		 150.4	     1408.0	 60544.0      13820.0	   13820.0   194    81	  2.938	  3.863

		 150.7	     1408.0	 60544.0      13820.0	   13820.0   194    81	  2.938	  3.863

       The Timestamp column reports the elapsed time in seconds since the
       start of the target JVM. In addition, the -gcoldcapacity output shows
       the old generation capacity (OGC) and the old space capacity (OC)
       increasing as the heap expands to meet allocation and/or promotion
       demands. The old generation capacity (OGC) has grown to from 11696 KB
       to 13820 KB after the 81st Full GC (FGC). The maximum capacity of the
       generation (and space) is 60544 KB (OGCMX), so it still has room to
       expand.

   Monitor
       instrumentation for a remote JVM

       This example attaches to lvmid 40496 on the system named remote.domain
       using the -gcutil option, with samples taken every second indefinitely.
       jstat -gcutil 40496@remote.domain 1000

       The lvmid is combined with the name of the remote host to construct a
       vmid of 40496@remote.domain. This vmid results in the use of the rmi
       protocol to communicate to the default jstatd server on the remote
       host. The jstatd server is located using the rmiregistry on
       remote.domain that is bound to the default rmiregistry port (port
       1099).

SEE ALSO
	  * java - the Java Application Launcher

	  * jps - the Java Process Status Application

	  * jstatd - the jvmstat daemon

	  * rmiregistry - the Java Remote Object Registry

				  06 Aug 2006			      jstat(1)
[top]

List of man pages available for Ubuntu

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net