java性能监控工具jstat-windows
Monitors Java Virtual Machine (JVM) statistics. This command is experimental and unsupported.
Synopsis
jstat [ generalOption | outputOptions vmid [ interval[s|ms] [ count ] ]
generalOption- outputOptions
One or more output options that consist of a single
statOption
, plus any of the-t
,-h
, and-J
options. See Output Options.- vmid
Virtual machine identifier, which is a string that indicates the target JVM. The general syntax is the following:
[protocol:][//]lvmid[@hostname[:port]/servername]
The syntax of the
vmid
string corresponds to the syntax of a URI. Thevmid
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.- interval [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
jstat
command produces its output at each interval.- count
Number of samples to display. The default value is infinity which causes the
jstat
command to display statistics until the target JVM terminates or thejstat
command is terminated. This value must be a positive integer.
Description
The jstat
command displays performance statistics for an instrumented Java HotSpot VM. The target JVM is identified by its virtual machine identifier, or vmid
option.
Virtual Machine Identifier
The syntax of the vmid
string corresponds to the syntax of a URI:
[protocol:][//]lvmid[@hostname[:port]/servername]
- protocol
The communications protocol. If the protocol value is omitted and a host name is not specified, then the default protocol is a platform-specific optimized local protocol. If the protocol value is omitted and a host name 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. Thelvmid
is the only required component of a virtual machine identifier. Thelvmid
is typically, but not necessarily, the operating system's process identifier for the target JVM process. You can use thejps
command to determine thelvmid
. Also, you can determine thelvmid
on Solaris, Linux, and OS X platforms with theps
command, and on Windows with the Windows Task Manager.- hostname
A hostname or IP address that indicates the target host. If the hostname value is omitted, then the target host is the local host.
- port
The default port for communicating with the remote server. If the hostname value is omitted or the protocol value specifies an optimized, local protocol, then the port value is ignored. Otherwise, treatment of the
port
parameter is implementation-specific. For the defaultrmi
protocol, the port value indicates the port number for the rmiregistry on the remote host. If the port value is omitted and the protocol value indicatesrmi
, then the default rmiregistry port (1099) is used.- servername
The treatment of the
servername
parameter depends on implementation. For the optimized local protocol, this field is ignored. For thermi
protocol, 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 the jstat
command to display simple usage and version information. Output options determine the content and format of the statistical output.
All options and their functionality are subject to change or removal in future releases.
General Options
If you specify one of the general options, then you cannot specify any other option or parameter.
-helpDisplays a help message.
-optionsStat Options and Output
The following information summarizes the columns that the jstat
command outputs for each statOption.
- -class option
Class loader statistics.
Loaded
: Number of classes loaded.Bytes
: Number of kBs loaded.Unloaded
: Number of classes unloaded.Bytes
: Number of Kbytes unloaded.Time
: Time spent performing class loading and unloading operations.- -compiler option
Java HotSpot VM Just-in-Time compiler statistics.
Compiled
: Number of compilation tasks performed.Failed
: Number of compilations tasks failed.Invalid
: Number of compilation tasks that were invalidated.Time
: Time spent performing compilation tasks.FailedType
: Compile type of the last failed compilation.FailedMethod
: Class name and method of the last failed compilation.- -gc option
Garbage-collected heap statistics.
S0C
: Current survivor space 0 capacity (kB).S1C
: Current survivor space 1 capacity (kB).S0U
: Survivor space 0 utilization (kB).S1U
: Survivor space 1 utilization (kB).EC
: Current eden space capacity (kB).EU
: Eden space utilization (kB).OC
: Current old space capacity (kB).OU
: Old space utilization (kB).MC
: Metaspace capacity (kB).MU
: Metacspace utilization (kB).CCSC
: Compressed class space capacity (kB).CCSU
: Compressed class space used (kB).YGC
: Number of young generation garbage collection events.YGCT
: Young generation garbage collection time.FGC
: Number of full GC events.FGCT
: Full garbage collection time.GCT
: Total garbage collection time.- -gccapacity option
Memory pool generation and space capacities.
NGCMN
: Minimum new generation capacity (kB).NGCMX
: Maximum new generation capacity (kB).NGC
: Current new generation capacity (kB).S0C
: Current survivor space 0 capacity (kB).S1C
: Current survivor space 1 capacity (kB).EC
: Current eden space capacity (kB).OGCMN
: Minimum old generation capacity (kB).OGCMX
: Maximum old generation capacity (kB).OGC
: Current old generation capacity (kB).OC
: Current old space capacity (kB).MCMN
: Minimum metaspace capacity (kB).MCMX
: Maximum metaspace capacity (kB).MC
: Metaspace capacity (kB).CCSMN
: Compressed class space minimum capacity (kB).CCSMX
: Compressed class space maximum capacity (kB).CCSC
: Compressed class space capacity (kB).YGC
: Number of young generation GC events.FGC
: Number of full GC events.- -gccause option
This option displays the same summary of garbage collection statistics as the
-gcutil
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-gcutil
, this option adds the following columns.LGCC
: Cause of last garbage collectionGCC
: Cause of current garbage collection- -gcnew option
New generation statistics.
S0C
: Current survivor space 0 capacity (kB).S1C
: Current survivor space 1 capacity (kB).S0U
: Survivor space 0 utilization (kB).S1U
: Survivor space 1 utilization (kB).TT
: Tenuring threshold.MTT
: Maximum tenuring threshold.DSS
: Desired survivor size (kB).EC
: Current eden space capacity (kB).EU
: Eden space utilization (kB).YGC
: Number of young generation GC events.YGCT
: Young generation garbage collection time.- -gcnewcapacity option
New generation space size statistics.
NGCMN
: Minimum new generation capacity (kB).NGCMX
: Maximum new generation capacity (kB).NGC
: Current new generation capacity (kB).S0CMX
: Maximum survivor space 0 capacity (kB).S0C
: Current survivor space 0 capacity (kB).S1CMX
: Maximum survivor space 1 capacity (kB).S1C
: Current survivor space 1 capacity (kB).ECMX
: Maximum eden space capacity (kB).EC
: Current eden space capacity (kB).YGC
: Number of young generation GC events.FGC
: Number of full GC events.- -gcold option
Old generation and metaspace behavior statistics.
MC
: Metaspace capacity (kB).MU
: Metaspace utilization (kB).CCSC
: Compressed class space capacity (kB).CCSU
: Compressed class space used (kB).OC
: Current old space capacity (kB).OU
: Old space utilization (kB).YGC
: Number of young generation GC events.FGC
: Number of full GC events.FGCT
: Full garbage collection time.GCT
: Total garbage collection time.- -gcoldcapacity option
Old generation size statistics.
OGCMN
: Minimum old generation capacity (kB).OGCMX
: Maximum old generation capacity (kB).OGC
: Current old generation capacity (kB).OC
: Current old space capacity (kB).YGC
: Number of young generation GC events.FGC
: Number of full GC events.FGCT
: Full garbage collection time.GCT
: Total garbage collection time.- -gcmetacapacity option
Metaspace size statistics.
MCMN
: Minimum metaspace capacity (kB).MCMX
: Maximum metaspace capacity (kB).MC
: Metaspace capacity (kB).CCSMN
: Compressed class space minimum capacity (kB).CCSMX
: Compressed class space maximum capacity (kB).YGC
: Number of young generation GC events.FGC
: Number of full GC events.FGCT
: Full garbage collection time.GCT
: Total garbage collection time.- -gcutil option
Summary of garbage collection statistics.
S0
: Survivor space 0 utilization as a percentage of the space's current capacity.S1
: Survivor space 1 utilization as a percentage of the space's current capacity.E
: Eden space utilization as a percentage of the space's current capacity.O
: Old space utilization as a percentage of the space's current capacity.M
: Metaspace utilization as a percentage of the space's current capacity.CCS
: Compressed class space utilization as a percentage.YGC
: Number of young generation GC events.YGCT
: Young generation garbage collection time.FGC
: Number of full GC events.FGCT
: Full garbage collection time.GCT
: Total garbage collection time.- -printcompilation option
Java HotSpot VM compiler method statistics.
Compiled
: Number of compilation tasks performed by the most recently compiled method.Size
: Number of bytes of byte code of the most recently compiled method.Type
: Compilation type of the most recently compiled method.Method
: 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-XX:+PrintCompilation
option.
Examples
This section presents some examples of monitoring a local JVM with an lvmid of 21891.
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 -gcutil
option.
The 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.
jstat -gcutil 21891 250 7 S0 S1 E O M CCS YGC YGCT FGC FGCT GCT 0.00 97.02 70.31 66.80 95.52 89.14 7 0.300 0 0.000 0.300 0.00 97.02 86.23 66.80 95.52 89.14 7 0.300 0 0.000 0.300 0.00 97.02 96.53 66.80 95.52 89.14 7 0.300 0 0.000 0.300 91.03 0.00 1.98 68.19 95.89 91.24 8 0.378 0 0.000 0.378 91.03 0.00 15.82 68.19 95.89 91.24 8 0.378 0 0.000 0.378 91.03 0.00 17.80 68.19 95.89 91.24 8 0.378 0 0.000 0.378 91.03 0.00 17.80 68.19 95.89 91.24 8 0.378 0 0.000 0.378
Repeat the Column Header String
This example attaches to lvmid 21891 and takes samples at 250 millisecond intervals and displays the output as specified by -gcnew
option. In addition, it uses the -h3
option to output the column header after every 3 lines of data.
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.
Another collection occurs between the fifth and sixth samples. This collection found very few survivors and returned the tenuring threshold to 31.
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
Include a Time Stamp for Each Sample
This example attaches to lvmid 21891 and takes 3 samples at 250 millisecond intervals. The -t
option is used to generate a time stamp for each sample in the first column.
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 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.
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
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.
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 thermiregistry
command on remote.domain
that is bound to the default port of the rmiregistry
command (port 1099).
jstat -gcutil 40496@remote.domain 1000 ... output omitted
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