|
11
|
1 |
jstat(1) jstat(1)
|
|
|
2 |
|
|
|
3 |
|
|
|
4 |
|
|
|
5 |
NAME
|
|
|
6 |
jstat - Java Virtual Machine statistics monitoring tool
|
|
|
7 |
|
|
|
8 |
SYNOPSIS
|
|
|
9 |
jstat [ generalOption | outputOptions vmid [ interval [ s|ms ] [ count ] ] ]
|
|
|
10 |
|
|
|
11 |
DESCRIPTION
|
|
|
12 |
The jstat tool displays performance statistics for an instrumented HotSpot Java virtual machine
|
|
|
13 |
(JVM). The target JVM is identified by its virtual machine identifier, or vmid option described
|
|
|
14 |
below.
|
|
|
15 |
|
|
|
16 |
NOTE - This utility is unsupported and may or may not be available in future versions of the J2SE
|
|
|
17 |
SDK. It is currently not available on Windows 98 and Windows ME platforms.
|
|
|
18 |
|
|
|
19 |
VIRTUAL MACHINE IDENTIFIER
|
|
|
20 |
The syntax of the vmid string largely corresponds to the syntax of a URI:
|
|
|
21 |
|
|
|
22 |
[protocol:][//]lvmid[@hostname][:port][/servername]
|
|
|
23 |
|
|
|
24 |
protocol The communications protocol. If the protocol is omitted and a hostname is not speci-
|
|
|
25 |
fied, the default protocol is a platform specific optimized local protocol. If the
|
|
|
26 |
protocol is omitted and a hostname is specified, then the default protocol is rmi.
|
|
|
27 |
|
|
|
28 |
lvmid The local virtual machine identifier for the target JVM. The lvmid is a platform-spe-
|
|
|
29 |
cific value that uniquely identifies a JVM on a system. The lvmid is the only required
|
|
|
30 |
component of a virtual machine identifier. The lvmid is typically, but not necessar-
|
|
|
31 |
ily, the operating system's process identifier for the target JVM process. You can use
|
|
|
32 |
the jps command to determine the lvmid. Also, you can determine lvmid on Unix plat-
|
|
|
33 |
forms with the ps command, and on Windows with the Windows Task Manager.
|
|
|
34 |
|
|
|
35 |
hostname A hostname or IP address indicating the target host. If hostname is omitted, then the
|
|
|
36 |
target host is the local host.
|
|
|
37 |
|
|
|
38 |
port The default port for communicating with the remote server. If the hostname is omitted
|
|
|
39 |
or the protocol specifies an optimized, local protocol, then port is ignored. Other-
|
|
|
40 |
wise, treatment of the port parameter is implementation specific. For the default rmi
|
|
|
41 |
protocol, the port indicates the port number for the rmiregistry on the remote host.
|
|
|
42 |
If port is omitted, and protocol indicates rmi, then the default rmiregistry port
|
|
|
43 |
(1099) is used.
|
|
|
44 |
|
|
|
45 |
servername The treatment of this parameter depends on implementation. For the optimized local
|
|
|
46 |
protocol, this field is ignored. For the rmi protocol, it represents the name of the
|
|
|
47 |
RMI remote object on the remote host.
|
|
|
48 |
|
|
|
49 |
PARAMETERS
|
|
|
50 |
generalOption A single general command-line option (-help, -options, or -version)
|
|
|
51 |
|
|
|
52 |
outputOptions One or more output options, consisting of a single statOption, plus any of the -t, -h,
|
|
|
53 |
and -J options.
|
|
|
54 |
|
|
|
55 |
vmid Virtual machine identifier, a string indicating the target Java virtual machine (JVM).
|
|
|
56 |
The general syntax is
|
|
|
57 |
|
|
|
58 |
[protocol:][//]lvmid[@hostname[:port]/servername
|
|
|
59 |
|
|
|
60 |
The syntax of the vmid string largely corresponds to the syntax of a URI. The vmid can vary from a
|
|
|
61 |
simple integer representing a local JVM to a more complex construction specifying a communications
|
|
|
62 |
protocol, port number, and other implementation-specific values. See Virtual Machine Identifier below
|
|
|
63 |
for details.
|
|
|
64 |
|
|
|
65 |
interval[s|ms] Sampling interval in the specified units, seconds (s) or milliseconds (ms). Default
|
|
|
66 |
units are milliseconds. Must be a positive integer. If specified, jstat will produce
|
|
|
67 |
its output at each interval.
|
|
|
68 |
|
|
|
69 |
count Number of samples to display. Default value is infinity; that is, jstat displays sta-
|
|
|
70 |
tistics until the target JVM terminates or the jstat command is terminated. Must be a
|
|
|
71 |
positive integer.
|
|
|
72 |
|
|
|
73 |
OPTIONS
|
|
|
74 |
The jstat command supports two types of options, general options and output options. General options
|
|
|
75 |
cause jstat to display simple usage and version information. Output options determine the content and
|
|
|
76 |
format of the statistical output.
|
|
|
77 |
|
|
|
78 |
NOTE- All options, and their functionality are subject to change or removal in future releases.
|
|
|
79 |
|
|
|
80 |
GENERAL OPTIONS
|
|
|
81 |
If you specify one of the general options, you cannot specify any other option or parameter.
|
|
|
82 |
|
|
|
83 |
-help Display help message.
|
|
|
84 |
|
|
|
85 |
-version Display version information.
|
|
|
86 |
|
|
|
87 |
-options Display list of statistics options. See the Output Options section below.
|
|
|
88 |
|
|
|
89 |
OUTPUT OPTIONS
|
|
|
90 |
If you do not specify a general option, then you can specify output options. Output options deter-
|
|
|
91 |
mine the content and format of jstat's output, and consist of a single statOption, plus any of the
|
|
|
92 |
other output options (-h, -t, and -J). The statOption must come first.
|
|
|
93 |
|
|
|
94 |
Output is formatted as a table, with columns are separated by spaces. A header row with titles
|
|
|
95 |
describes the columns. Use the -h option to set the frequency at which the header is displayed.
|
|
|
96 |
Column header names are generally consistent between the different options. In general, if two
|
|
|
97 |
options provide a column with the same name, then the data source for the two columns are the same.
|
|
|
98 |
|
|
|
99 |
Use the -t option to display a time stamp column, labeled Timestamp as the first column of output.
|
|
|
100 |
The Timestamp column contains the elapsed time, in seconds, since startup of the target JVM. The res-
|
|
|
101 |
olution of the time stamp is dependent on various factors and is subject to variation due to delayed
|
|
|
102 |
thread scheduling on heavily loaded systems.
|
|
|
103 |
|
|
|
104 |
Use the interval and count parameters to determine how frequently and how many times, respectively,
|
|
|
105 |
jstat displays its output.
|
|
|
106 |
|
|
|
107 |
NOTE- You are advised not to write scripts to parse jstat's output since the format may change in
|
|
|
108 |
future releases. If you choose to write scripts that parse jstat output, expect to modify them for
|
|
|
109 |
future releases of this tool.
|
|
|
110 |
|
|
|
111 |
-statOption Determines the statistics information that jstat displays. The following table lists
|
|
|
112 |
the available options. Use the -options general option to display the list of options
|
|
|
113 |
for a particular platform installation.
|
|
|
114 |
|
|
|
115 |
|
|
|
116 |
|
|
|
117 |
+-----------------+------------------------------------------------------+
|
|
|
118 |
| Option | Displays... |
|
|
|
119 |
+-----------------+------------------------------------------------------+
|
|
|
120 |
|class | Statistics on the behavior of the class loader |
|
|
|
121 |
|compiler | Statistics on the behavior of the HotSpot Just-In- |
|
|
|
122 |
| | Time compiler |
|
|
|
123 |
|gc | Statistics on the behavior of the garbage collected |
|
|
|
124 |
| | heap |
|
|
|
125 |
|gccapacity | Statistics of the capacities of the generations and |
|
|
|
126 |
| | their corresponding spaces. |
|
|
|
127 |
|gccause | Summary of garbage collection statistics (same as |
|
|
|
128 |
| | -gcutil), with the cause of the last and current (if |
|
|
|
129 |
| | applicable) garbage collection events. |
|
|
|
130 |
|gcnew | Statistics of the behavior of the new generation. |
|
|
|
131 |
|gcnewcapacity | Statistics of the sizes of the new generations and |
|
|
|
132 |
| | its corresponding spaces. |
|
|
|
133 |
|gcold | Statistics of the behavior of the old and permanent |
|
|
|
134 |
| | generations. |
|
|
|
135 |
|gcoldcapacity | Statistics of the sizes of the old generation. |
|
|
|
136 |
|gcpermcapacity | Statistics of the sizes of the permanent generation. |
|
|
|
137 |
|gcutil | Summary of garbage collection statistics. |
|
|
|
138 |
|printcompilation | Summary of garbage collection statistics. |
|
|
|
139 |
+-----------------+------------------------------------------------------+
|
|
|
140 |
-h n Display a column header every n samples (output rows), where n is a positive integer.
|
|
|
141 |
Default value is 0, which displays the column header above the first row of data.
|
|
|
142 |
|
|
|
143 |
-t n Display a timestamp column as the first column of output. The timestamp is the the
|
|
|
144 |
time since the start time of the target JVM.
|
|
|
145 |
|
|
|
146 |
-JjavaOption Pass javaOption to the java application launcher. For example, -J-Xms48m sets the
|
|
|
147 |
startup memory to 48 megabytes. For a complete list of options, see java(1).
|
|
|
148 |
|
|
|
149 |
STATOPTIONS AND OUTPUT
|
|
|
150 |
The following tables summarize the columns that jstat outputs for each statOption.
|
|
|
151 |
|
|
|
152 |
class Class Loader Statistics
|
|
|
153 |
|
|
|
154 |
|
|
|
155 |
|
|
|
156 |
+---------+--------------------------------------------------------+
|
|
|
157 |
| Column | Description |
|
|
|
158 |
+---------+--------------------------------------------------------+
|
|
|
159 |
|Loaded | Number of classes loaded |
|
|
|
160 |
|Bytes | Number of Kbytes loaded |
|
|
|
161 |
|Unloaded | Number of classes unloaded |
|
|
|
162 |
|Bytes | Number of Kbytes unloaded |
|
|
|
163 |
|Time | Time spent performing class load and unload operations |
|
|
|
164 |
+---------+--------------------------------------------------------+
|
|
|
165 |
compiler
|
|
|
166 |
HotSpot Just-In-Time Compiler Statistics
|
|
|
167 |
|
|
|
168 |
|
|
|
169 |
|
|
|
170 |
+-------------+-------------------------------------------------------+
|
|
|
171 |
| Column | Description |
|
|
|
172 |
+-------------+-------------------------------------------------------+
|
|
|
173 |
|Compiled | Humber of compilation tasks performed |
|
|
|
174 |
|Failed | Number of compilation tasks that failed |
|
|
|
175 |
|Invalid | Number of compilation tasks that were invalidated |
|
|
|
176 |
|Time | Time spent performing compilation tasks |
|
|
|
177 |
|FailedType | Compile type of the last failed compilation |
|
|
|
178 |
|FailedMethod | Class name and method for the last failed compilation |
|
|
|
179 |
+-------------+-------------------------------------------------------+
|
|
|
180 |
gc Garbage-collected heap statistics
|
|
|
181 |
|
|
|
182 |
|
|
|
183 |
|
|
|
184 |
+-------+-------------------------------------------+
|
|
|
185 |
|Column | Description |
|
|
|
186 |
+-------+-------------------------------------------+
|
|
|
187 |
|SOC | Current survivor space 0 capacity (KB). |
|
|
|
188 |
|S1C | Current survivor space 1 capacity (KB). |
|
|
|
189 |
|S0U | Survivor space 0 utilization (KB). |
|
|
|
190 |
|S1U | Survivor space 1 utilization (KB). |
|
|
|
191 |
|EC | Current eden space capacity (KB). |
|
|
|
192 |
|EU | Eden space utilization (KB). |
|
|
|
193 |
|OC | Current old space capacity (KB). |
|
|
|
194 |
|OU | Old space utilization (KB). |
|
|
|
195 |
|PC | Current permanent space capacity (KB). |
|
|
|
196 |
|PU | Permanent space utilization (KB). |
|
|
|
197 |
|YGC | Number of young generation GC Events. |
|
|
|
198 |
|YGCT | Young generation garbage collection time. |
|
|
|
199 |
|FGC | Number of full GC events. |
|
|
|
200 |
|FGCT | Full garbage collection time. |
|
|
|
201 |
|GCT | Total garbage collection time. |
|
|
|
202 |
+-------+-------------------------------------------+
|
|
|
203 |
gccapacity
|
|
|
204 |
Memory Pool Generation and Space Capacities
|
|
|
205 |
|
|
|
206 |
|
|
|
207 |
|
|
|
208 |
+-------+---------------------------------------------+
|
|
|
209 |
|Column | Description |
|
|
|
210 |
+-------+---------------------------------------------+
|
|
|
211 |
|NGCMN | Minimum new generation capacity (KB). |
|
|
|
212 |
|NGCMX | Maximum new generation capacity (KB). |
|
|
|
213 |
|NGC | Current new generation capacity (KB). |
|
|
|
214 |
|S0C | Current survivor space 0 capacity (KB). |
|
|
|
215 |
|S1C | Current survivor space 1 capacity (KB). |
|
|
|
216 |
|EC | Current eden space capacity (KB). |
|
|
|
217 |
|OGCMN | Minimum old generation capacity (KB). |
|
|
|
218 |
|OGCMX | Maximum old generation capacity (KB). |
|
|
|
219 |
|OGC | Current old generation capacity (KB). |
|
|
|
220 |
|OC | Current old space capacity (KB). |
|
|
|
221 |
|PGCMN | Minimum permanent generation capacity (KB). |
|
|
|
222 |
|PGCMX | Maximum Permanent generation capacity (KB). |
|
|
|
223 |
|PGC | Current Permanent generation capacity (KB). |
|
|
|
224 |
|PC | Current Permanent space capacity (KB). |
|
|
|
225 |
|VGC | Number of Young generation GC Events. |
|
|
|
226 |
|FGC | Number of Full GC Events. |
|
|
|
227 |
+-------+---------------------------------------------+
|
|
|
228 |
gccause
|
|
|
229 |
This option displays the same summary of garbage collection statistics as the -gcutil option,
|
|
|
230 |
but includes the causes of the last garbage collection event and (if applicable) the current
|
|
|
231 |
garbage collection event. In addition to the columns listed for -gcutil, this option adds the
|
|
|
232 |
following columns:
|
|
|
233 |
|
|
|
234 |
|
|
|
235 |
|
|
|
236 |
+-------+--------------------------------------+
|
|
|
237 |
|Column | Description |
|
|
|
238 |
+-------+--------------------------------------+
|
|
|
239 |
|LGCC | Cause of last Garbage Collection. |
|
|
|
240 |
|GCC | Cause of current Garbage Collection. |
|
|
|
241 |
+-------+--------------------------------------+
|
|
|
242 |
gcnew New Generation Statistics
|
|
|
243 |
|
|
|
244 |
|
|
|
245 |
|
|
|
246 |
+-------+-------------------------------------------+
|
|
|
247 |
|Column | Description |
|
|
|
248 |
+-------+-------------------------------------------+
|
|
|
249 |
|SOC | Current survivor space 0 capacity (KB). |
|
|
|
250 |
|S1C | Current survivor space 1 capacity (KB). |
|
|
|
251 |
|S0U | Survivor space 0 utilization (KB). |
|
|
|
252 |
|S1U | Survivor space 1 utilization (KB). |
|
|
|
253 |
|TT | Tenuring threshold. |
|
|
|
254 |
|MTT | Maximum tenuring threshold. |
|
|
|
255 |
|DSS | Desired survivor size (KB). |
|
|
|
256 |
|EC | Current eden space capacity (KB). |
|
|
|
257 |
|EU | Eden space utilization (KB). |
|
|
|
258 |
|VGC | Number of young generation GC events. |
|
|
|
259 |
|VGCT | Young generation garbage collection time. |
|
|
|
260 |
+-------+-------------------------------------------+
|
|
|
261 |
gcnewcapacity
|
|
|
262 |
New Generation Space Size Statistics
|
|
|
263 |
|
|
|
264 |
|
|
|
265 |
|
|
|
266 |
+-------+-----------------------------------------+
|
|
|
267 |
|Column | Description |
|
|
|
268 |
+-------+-----------------------------------------+
|
|
|
269 |
|NGCMN | Minimum new generation capacity (KB). |
|
|
|
270 |
|NGCMX | Maximum new generation capacity (KB). |
|
|
|
271 |
|NGC | Current new generation capacity (KB). |
|
|
|
272 |
|S0CMX | Maximum survivor space 0 capacity (KB). |
|
|
|
273 |
|S0C | Current survivor space 0 capacity (KB). |
|
|
|
274 |
|S1CMX | Maximum survivor space 1 capacity (KB). |
|
|
|
275 |
|S1C | Current survivor space 1 capacity (KB). |
|
|
|
276 |
|ECMX | Maximum eden space capacity (KB). |
|
|
|
277 |
|EC | Current eden space capacity (KB). |
|
|
|
278 |
|YGC | Number of young generation GC events. |
|
|
|
279 |
|FGC | Number of Full GC Events. |
|
|
|
280 |
+-------+-----------------------------------------+
|
|
|
281 |
gcold Old and Permanent Generation Statistics
|
|
|
282 |
|
|
|
283 |
|
|
|
284 |
|
|
|
285 |
+-------+----------------------------------------+
|
|
|
286 |
|Column | Description |
|
|
|
287 |
+-------+----------------------------------------+
|
|
|
288 |
|PC | Current permanent space capacity (KB). |
|
|
|
289 |
|PU | Permanent space utilization (KB). |
|
|
|
290 |
|OC | Current old space capacity (KB). |
|
|
|
291 |
|OU | Old space utilization (KB). |
|
|
|
292 |
|YGC | Number of young generation GC events. |
|
|
|
293 |
|FGC | Number of Full GC events. |
|
|
|
294 |
|FGCT | Full garbage collection time. |
|
|
|
295 |
|GCT | Total garbage collection time. |
|
|
|
296 |
+-------+----------------------------------------+
|
|
|
297 |
gcoldcapacity
|
|
|
298 |
Old Generation Statistics
|
|
|
299 |
|
|
|
300 |
|
|
|
301 |
|
|
|
302 |
+-------+---------------------------------------+
|
|
|
303 |
|Column | Description |
|
|
|
304 |
+-------+---------------------------------------+
|
|
|
305 |
|OGCMN | Minimum old generation capacity (KB). |
|
|
|
306 |
|OGCMV | Maximum old generation capacity (KB). |
|
|
|
307 |
|OGC | Current old generation capacity (KB). |
|
|
|
308 |
|OC | Current old space capacity (KB). |
|
|
|
309 |
|YGC | Number of young generation GC events. |
|
|
|
310 |
|FGC | Number of Full GC events. |
|
|
|
311 |
|FGCT | Full garbage collection time. |
|
|
|
312 |
|GCT | Total garbage collection time. |
|
|
|
313 |
+-------+---------------------------------------+
|
|
|
314 |
gcpermcapacity
|
|
|
315 |
Permanent Generation Statistics
|
|
|
316 |
|
|
|
317 |
|
|
|
318 |
|
|
|
319 |
+-------+---------------------------------------------+
|
|
|
320 |
|Column | Description |
|
|
|
321 |
+-------+---------------------------------------------+
|
|
|
322 |
|PGCMN | Minimum permanent generation capacity (KB). |
|
|
|
323 |
|PGCMX | Maximum permanent generation capacity (KB). |
|
|
|
324 |
|PGC | Current permanent generation capacity (KB). |
|
|
|
325 |
|PC | Current permanent space capacity (KB). |
|
|
|
326 |
|YGC | Number of young generation GC events. |
|
|
|
327 |
|FGC | Number of Full GC events. |
|
|
|
328 |
|FGCT | Full garbage collection time. |
|
|
|
329 |
|GCT | Total garbage collection time. |
|
|
|
330 |
+-------+---------------------------------------------+
|
|
|
331 |
gcutil Summary of Garbage Collection Statistics
|
|
|
332 |
|
|
|
333 |
|
|
|
334 |
|
|
|
335 |
+-------+-------------------------------------------+
|
|
|
336 |
|Column | Description |
|
|
|
337 |
+-------+-------------------------------------------+
|
|
|
338 |
|S0 | Survivor space 0 utilization as a per- |
|
|
|
339 |
| | centage of the space's current capacity. |
|
|
|
340 |
|S1 | Survivor space 1 utilization as a per- |
|
|
|
341 |
| | centage of the space's current capacity. |
|
|
|
342 |
|E | Eden space utilization as a percentage of |
|
|
|
343 |
| | the space's current capacity. |
|
|
|
344 |
|O | Old space utilization as a percentage of |
|
|
|
345 |
| | the space's current capacity. |
|
|
|
346 |
|P | Permanent space utilization as a percent- |
|
|
|
347 |
| | age of the space's current capacity. |
|
|
|
348 |
|YGC | Number of young generation GC events. |
|
|
|
349 |
|YGCT | Young generation garbage collection time. |
|
|
|
350 |
|FGC | Number of Full GC events. |
|
|
|
351 |
|FGCT | Full garbage collection time. |
|
|
|
352 |
|GCT | Total garbage collection time. |
|
|
|
353 |
+-------+-------------------------------------------+
|
|
|
354 |
printcompilation
|
|
|
355 |
HotSpot Compiler Method Statistics
|
|
|
356 |
|
|
|
357 |
|
|
|
358 |
|
|
|
359 |
+---------+---------------------------------------------+
|
|
|
360 |
| Column | Description |
|
|
|
361 |
+---------+---------------------------------------------+
|
|
|
362 |
|Compiled | Number of compilation tasks performed. |
|
|
|
363 |
|Size | Number of bytes of bytecode for the method. |
|
|
|
364 |
|Type | Compilation type. |
|
|
|
365 |
|Method | Class name and method name identifying the |
|
|
|
366 |
| | compiled method. Class name uses "/" |
|
|
|
367 |
| | instead of "." as namespace separator. |
|
|
|
368 |
| | Method name is the method within the given |
|
|
|
369 |
| | class. The format for these two fields is |
|
|
|
370 |
| | consistent with the HotSpot - XX:+PrintCom- |
|
|
|
371 |
| | plation option. |
|
|
|
372 |
+---------+---------------------------------------------+
|
|
|
373 |
|
|
|
374 |
EXAMPLES
|
|
|
375 |
This section presents some examples of monitoring a local JVM with a lvmid of 21891.
|
|
|
376 |
|
|
|
377 |
Using the gcutil option
|
|
|
378 |
This example attaches to lvmid 21891 and takes 7 samples at 250 millisecond intervals and displays
|
|
|
379 |
the output as specified by the -gcutil option.
|
|
|
380 |
|
|
|
381 |
jstat -gcutil 21891 250 7
|
|
|
382 |
S0 S1 E O P YGC YGCT FGC FGCT GCT
|
|
|
383 |
12.44 0.00 27.20 9.49 96.70 78 0.176 5 0.495 0.672
|
|
|
384 |
12.44 0.00 62.16 9.49 96.70 78 0.176 5 0.495 0.672
|
|
|
385 |
12.44 0.00 83.97 9.49 96.70 78 0.176 5 0.495 0.672
|
|
|
386 |
0.00 7.74 0.00 9.51 96.70 79 0.177 5 0.495 0.673
|
|
|
387 |
0.00 7.74 23.37 9.51 96.70 79 0.177 5 0.495 0.673
|
|
|
388 |
0.00 7.74 43.82 9.51 96.70 79 0.177 5 0.495 0.673
|
|
|
389 |
0.00 7.74 58.11 9.51 96.71 79 0.177 5 0.495 0.673
|
|
|
390 |
|
|
|
391 |
The output of this example shows that a young generation collection occurred between the 3rd and 4th
|
|
|
392 |
sample. The collection took 0.001 seconds and promoted objects from the eden space (E) to the old
|
|
|
393 |
space (O), resulting in an increase of old space utilization from 9.49% to 9.51%. Before the collec-
|
|
|
394 |
tion, the survivor space was 12.44% utilized, but after this collection it is only 7.74% utilized.
|
|
|
395 |
|
|
|
396 |
Repeating the column header string
|
|
|
397 |
This example attaches to lvmid 21891 and takes samples at 250 millisecond intervals and displays the
|
|
|
398 |
output as specified by -gcutil option. In addition, it uses the -h3 option to output the column
|
|
|
399 |
header after every 3 lines of data.
|
|
|
400 |
|
|
|
401 |
jstat -gcnew -h3 21891 250
|
|
|
402 |
S0C S1C S0U S1U TT MTT DSS EC EU YGC YGCT
|
|
|
403 |
64.0 64.0 0.0 31.7 31 31 32.0 512.0 178.6 249 0.203
|
|
|
404 |
64.0 64.0 0.0 31.7 31 31 32.0 512.0 355.5 249 0.203
|
|
|
405 |
64.0 64.0 35.4 0.0 2 31 32.0 512.0 21.9 250 0.204
|
|
|
406 |
S0C S1C S0U S1U TT MTT DSS EC EU YGC YGCT
|
|
|
407 |
64.0 64.0 35.4 0.0 2 31 32.0 512.0 245.9 250 0.204
|
|
|
408 |
64.0 64.0 35.4 0.0 2 31 32.0 512.0 421.1 250 0.204
|
|
|
409 |
64.0 64.0 0.0 19.0 31 31 32.0 512.0 84.4 251 0.204
|
|
|
410 |
S0C S1C S0U S1U TT MTT DSS EC EU YGC YGCT
|
|
|
411 |
64.0 64.0 0.0 19.0 31 31 32.0 512.0 306.7 251 0.204
|
|
|
412 |
|
|
|
413 |
In addition to showing the repeating header string, this example shows that between the 2nd and 3rd
|
|
|
414 |
samples, a young GC occurred. Its duration was 0.001 seconds. The collection found enough live data
|
|
|
415 |
that the survivor space 0 utilization (S0U) would would have exceeded the desired survivor Size
|
|
|
416 |
(DSS). As a result, objects were promoted to the old generation (not visible in this output), and the
|
|
|
417 |
tenuring threshold (TT) was lowered from 31 to 2.
|
|
|
418 |
|
|
|
419 |
Another collection occurs between the 5th and 6th samples. This collection found very few survivors
|
|
|
420 |
and returned the tenuring threshold to 31.
|
|
|
421 |
|
|
|
422 |
Including a time stamp for each sample
|
|
|
423 |
This example attaches to lvmid 21891 and takes 3 samples at 250 millisecond intervals. The -t option
|
|
|
424 |
is used to generate a time stamp for each sample in the first column.
|
|
|
425 |
|
|
|
426 |
jstat -gcoldcapacity -t 21891 250 3
|
|
|
427 |
Timestamp OGCMN OGCMX OGC OC YGC FGC FGCT GCT
|
|
|
428 |
150.1 1408.0 60544.0 11696.0 11696.0 194 80 2.874 3.799
|
|
|
429 |
150.4 1408.0 60544.0 13820.0 13820.0 194 81 2.938 3.863
|
|
|
430 |
150.7 1408.0 60544.0 13820.0 13820.0 194 81 2.938 3.863
|
|
|
431 |
|
|
|
432 |
Monitor instrumentation for a remote JVM
|
|
|
433 |
This example attaches to lvmid 40496 on the system named remote.domain using the -gcutil option, with
|
|
|
434 |
samples taken every second indefinitely.
|
|
|
435 |
|
|
|
436 |
jstat -gcutil 40496@remote.domain 1000
|
|
|
437 |
... output omitted
|
|
|
438 |
|
|
|
439 |
The lvmid is combined with the name of the remote host to construct a vmid of 40496@remote.domain.
|
|
|
440 |
This vmid results in the use of the rmi protocol to communicate to the default jstatd server on the
|
|
|
441 |
remote host. The jstatd server is located using the rmiregistry on remote.domain that is bound to the
|
|
|
442 |
default rmiregistry port (port 1099).
|
|
|
443 |
|
|
|
444 |
SEE ALSO
|
|
|
445 |
java(1) jps(1) jstatd(1) rmiregistry(1)
|
|
|
446 |
|