1jstat(1)                       Monitoring Tools                       jstat(1)
2
3
4

NAME

6       jstat - Monitors Java Virtual Machine (JVM) statistics. This command is
7       experimental and unsupported.
8

SYNOPSIS

10           jstat [ generalOption | outputOptions vmid [ interval[s|ms] [ count ] ]
11
12       generalOption
13           A single general command-line option -help or -options. See General
14           Options.
15
16       outputOptions
17           One or more output options that consist of a single statOption,
18           plus any of the -t, -h, and -J options. See Output Options.
19
20       vmid
21           Virtual machine identifier, which is a string that indicates the
22           target JVM. The general syntax is the following:
23
24               [protocol:][//]lvmid[@hostname[:port]/servername]
25
26           The syntax of the vmid string corresponds to the syntax of a URI.
27           The vmid string can vary from a simple integer that represents a
28           local JVM to a more complex construction that specifies a
29           communications protocol, port number, and other
30           implementation-specific values. See Virtual Machine Identifier.
31
32       interval [s|ms]
33           Sampling interval in the specified units, seconds (s) or
34           milliseconds (ms). Default units are milliseconds. Must be a
35           positive integer. When specified, the jstat command produces its
36           output at each interval.
37
38       count
39           Number of samples to display. The default value is infinity which
40           causes the jstat command to display statistics until the target JVM
41           terminates or the jstat command is terminated. This value must be a
42           positive integer.
43

DESCRIPTION

45       The jstat command displays performance statistics for an instrumented
46       Java HotSpot VM. The target JVM is identified by its virtual machine
47       identifier, or vmid option.
48

VIRTUAL MACHINE IDENTIFIER

50       The syntax of the vmid string corresponds to the syntax of a URI:
51
52           [protocol:][//]lvmid[@hostname[:port]/servername]
53
54
55       protocol
56           The communications protocol. If the protocol value is omitted and a
57           host name is not specified, then the default protocol is a
58           platform-specific optimized local protocol. If the protocol value
59           is omitted and a host name is specified, then the default protocol
60           is rmi.
61
62       lvmid
63           The local virtual machine identifier for the target JVM. The lvmid
64           is a platform-specific value that uniquely identifies a JVM on a
65           system. The lvmid is the only required component of a virtual
66           machine identifier. The lvmid is typically, but not necessarily,
67           the operating system's process identifier for the target JVM
68           process. You can use the jps command to determine the lvmid. Also,
69           you can determine the lvmid on Solaris, Linux, and OS X platforms
70           with the ps command, and on Windows with the Windows Task Manager.
71
72       hostname
73           A hostname or IP address that indicates the target host. If the
74           hostname value is omitted, then the target host is the local host.
75
76       port
77           The default port for communicating with the remote server. If the
78           hostname value is omitted or the protocol value specifies an
79           optimized, local protocol, then the port value is ignored.
80           Otherwise, treatment of the port parameter is
81           implementation-specific. For the default rmi protocol, the port
82           value indicates the port number for the rmiregistry on the remote
83           host. If the port value is omitted and the protocol value indicates
84           rmi, then the default rmiregistry port (1099) is used.
85
86       servername
87           The treatment of the servername parameter depends on
88           implementation. For the optimized local protocol, this field is
89           ignored. For the rmi protocol, it represents the name of the RMI
90           remote object on the remote host.
91

OPTIONS

93       The jstat command supports two types of options, general options and
94       output options. General options cause the jstat command to display
95       simple usage and version information. Output options determine the
96       content and format of the statistical output.
97
98       All options and their functionality are subject to change or removal in
99       future releases.
100
101   General Options
102       If you specify one of the general options, then you cannot specify any
103       other option or parameter.
104
105       -help
106           Displays a help message.
107
108       -options
109           Displays a list of static options. See Output Options.
110
111   Output Options
112       If you do not specify a general option, then you can specify output
113       options. Output options determine the content and format of the jstat
114       command's output, and consist of a single statOption, plus any of the
115       other output options (-h, -t, and -J). The statOption must come first.
116
117       Output is formatted as a table, with columns that are separated by
118       spaces. A header row with titles describes the columns. Use the -h
119       option to set the frequency at which the header is displayed. Column
120       header names are consistent among the different options. In general, if
121       two options provide a column with the same name, then the data source
122       for the two columns is the same.
123
124       Use the -t option to display a time stamp column, labeled Timestamp as
125       the first column of output. The Timestamp column contains the elapsed
126       time, in seconds, since the target JVM started. The resolution of the
127       time stamp is dependent on various factors and is subject to variation
128       due to delayed thread scheduling on heavily loaded systems.
129
130       Use the interval and count parameters to determine how frequently and
131       how many times, respectively, the jstat command displays its output.
132
133       Note: Do not to write scripts to parse the jstat command's output
134       because the format might change in future releases. If you write
135       scripts that parse jstat command output, then expect to modify them for
136       future releases of this tool.
137
138       -statOption
139           Determines the statistics information the jstat command displays.
140           The following lists the available options. Use the -options general
141           option to display the list of options for a particular platform
142           installation. See Stat Options and Output.
143
144           class: Displays statistics about the behavior of the class loader.
145
146           compiler: Displays statistics about the behavior of the Java
147           HotSpot VM Just-in-Time compiler.
148
149           gc: Displays statistics about the behavior of the garbage collected
150           heap.
151
152           gccapacity: Displays statistics about the capacities of the
153           generations and their corresponding spaces.
154
155           gccause: Displays a summary about garbage collection statistics
156           (same as -gcutil), with the cause of the last and current (when
157           applicable) garbage collection events.
158
159           gcnew: Displays statistics of the behavior of the new generation.
160
161           gcnewcapacity: Displays statistics about the sizes of the new
162           generations and its corresponding spaces.
163
164           gcold: Displays statistics about the behavior of the old generation
165           and metaspace statistics.
166
167           gcoldcapacity: Displays statistics about the sizes of the old
168           generation.
169
170           gcmetacapacity: Displays statistics about the sizes of the
171           metaspace.
172
173           gcutil: Displays a summary about garbage collection statistics.
174
175           printcompilation: Displays Java HotSpot VM compilation method
176           statistics.
177
178       -h n
179           Displays a column header every n samples (output rows), where n is
180           a positive integer. Default value is 0, which displays the column
181           header the first row of data.
182
183       -t
184           Displays a timestamp column as the first column of output. The time
185           stamp is the time since the start time of the target JVM.
186
187       -JjavaOption
188           Passes javaOption to the Java application launcher. For example,
189           -J-Xms48m sets the startup memory to 48 MB. For a complete list of
190           options, see java(1).
191
192   Stat Options and Output
193       The following information summarizes the columns that the jstat command
194       outputs for each statOption.
195
196       -class option
197           Class loader statistics.
198
199           Loaded: Number of classes loaded.
200
201           Bytes: Number of kBs loaded.
202
203           Unloaded: Number of classes unloaded.
204
205           Bytes: Number of Kbytes unloaded.
206
207           Time: Time spent performing class loading and unloading operations.
208
209       -compiler option
210           Java HotSpot VM Just-in-Time compiler statistics.
211
212           Compiled: Number of compilation tasks performed.
213
214           Failed: Number of compilations tasks failed.
215
216           Invalid: Number of compilation tasks that were invalidated.
217
218           Time: Time spent performing compilation tasks.
219
220           FailedType: Compile type of the last failed compilation.
221
222           FailedMethod: Class name and method of the last failed compilation.
223
224       -gc option
225           Garbage-collected heap statistics.
226
227           S0C: Current survivor space 0 capacity (kB).
228
229           S1C: Current survivor space 1 capacity (kB).
230
231           S0U: Survivor space 0 utilization (kB).
232
233           S1U: Survivor space 1 utilization (kB).
234
235           EC: Current eden space capacity (kB).
236
237           EU: Eden space utilization (kB).
238
239           OC: Current old space capacity (kB).
240
241           OU: Old space utilization (kB).
242
243           MC: Metaspace capacity (kB).
244
245           MU: Metacspace utilization (kB).
246
247           CCSC: Compressed class space capacity (kB).
248
249           CCSU: Compressed class space used (kB).
250
251           YGC: Number of young generation garbage collection events.
252
253           YGCT: Young generation garbage collection time.
254
255           FGC: Number of full GC events.
256
257           FGCT: Full garbage collection time.
258
259           GCT: Total garbage collection time.
260
261       -gccapacity option
262           Memory pool generation and space capacities.
263
264           NGCMN: Minimum new generation capacity (kB).
265
266           NGCMX: Maximum new generation capacity (kB).
267
268           NGC: Current new generation capacity (kB).
269
270           S0C: Current survivor space 0 capacity (kB).
271
272           S1C: Current survivor space 1 capacity (kB).
273
274           EC: Current eden space capacity (kB).
275
276           OGCMN: Minimum old generation capacity (kB).
277
278           OGCMX: Maximum old generation capacity (kB).
279
280           OGC: Current old generation capacity (kB).
281
282           OC: Current old space capacity (kB).
283
284           MCMN: Minimum metaspace capacity (kB).
285
286           MCMX: Maximum metaspace capacity (kB).
287
288           MC: Metaspace capacity (kB).
289
290           CCSMN: Compressed class space minimum capacity (kB).
291
292           CCSMX: Compressed class space maximum capacity (kB).
293
294           CCSC: Compressed class space capacity (kB).
295
296           YGC: Number of young generation GC events.
297
298           FGC: Number of full GC events.
299
300       -gccause option
301           This option displays the same summary of garbage collection
302           statistics as the -gcutil option, but includes the causes of the
303           last garbage collection event and (when applicable) the current
304           garbage collection event. In addition to the columns listed for
305           -gcutil, this option adds the following columns.
306
307           LGCC: Cause of last garbage collection
308
309           GCC: Cause of current garbage collection
310
311       -gcnew option
312           New generation statistics.
313
314           S0C: Current survivor space 0 capacity (kB).
315
316           S1C: Current survivor space 1 capacity (kB).
317
318           S0U: Survivor space 0 utilization (kB).
319
320           S1U: Survivor space 1 utilization (kB).
321
322           TT: Tenuring threshold.
323
324           MTT: Maximum tenuring threshold.
325
326           DSS: Desired survivor size (kB).
327
328           EC: Current eden space capacity (kB).
329
330           EU: Eden space utilization (kB).
331
332           YGC: Number of young generation GC events.
333
334           YGCT: Young generation garbage collection time.
335
336       -gcnewcapacity option
337           New generation space size statistics.
338
339           NGCMN: Minimum new generation capacity (kB).
340
341           NGCMX: Maximum new generation capacity (kB).
342
343           NGC: Current new generation capacity (kB).
344
345           S0CMX: Maximum survivor space 0 capacity (kB).
346
347           S0C: Current survivor space 0 capacity (kB).
348
349           S1CMX: Maximum survivor space 1 capacity (kB).
350
351           S1C: Current survivor space 1 capacity (kB).
352
353           ECMX: Maximum eden space capacity (kB).
354
355           EC: Current eden space capacity (kB).
356
357           YGC: Number of young generation GC events.
358
359           FGC: Number of full GC events.
360
361       -gcold option
362           Old generation and metaspace behavior statistics.
363
364           MC: Metaspace capacity (kB).
365
366           MU: Metaspace utilization (kB).
367
368           CCSC: Compressed class space capacity (kB).
369
370           CCSU: Compressed class space used (kB).
371
372           OC: Current old space capacity (kB).
373
374           OU: Old space utilization (kB).
375
376           YGC: Number of young generation GC events.
377
378           FGC: Number of full GC events.
379
380           FGCT: Full garbage collection time.
381
382           GCT: Total garbage collection time.
383
384       -gcoldcapacity option
385           Old generation size statistics.
386
387           OGCMN: Minimum old generation capacity (kB).
388
389           OGCMX: Maximum old generation capacity (kB).
390
391           OGC: Current old generation capacity (kB).
392
393           OC: Current old space capacity (kB).
394
395           YGC: Number of young generation GC events.
396
397           FGC: Number of full GC events.
398
399           FGCT: Full garbage collection time.
400
401           GCT: Total garbage collection time.
402
403       -gcmetacapacity option
404           Metaspace size statistics.
405
406           MCMN: Minimum metaspace capacity (kB).
407
408           MCMX: Maximum metaspace capacity (kB).
409
410           MC: Metaspace capacity (kB).
411
412           CCSMN: Compressed class space minimum capacity (kB).
413
414           CCSMX: Compressed class space maximum capacity (kB).
415
416           YGC: Number of young generation GC events.
417
418           FGC: Number of full GC events.
419
420           FGCT: Full garbage collection time.
421
422           GCT: Total garbage collection time.
423
424       -gcutil option
425           Summary of garbage collection statistics.
426
427           S0: Survivor space 0 utilization as a percentage of the space's
428           current capacity.
429
430           S1: Survivor space 1 utilization as a percentage of the space's
431           current capacity.
432
433           E: Eden space utilization as a percentage of the space's current
434           capacity.
435
436           O: Old space utilization as a percentage of the space's current
437           capacity.
438
439           M: Metaspace utilization as a percentage of the space's current
440           capacity.
441
442           CCS: Compressed class space utilization as a percentage.
443
444           YGC: Number of young generation GC events.
445
446           YGCT: Young generation garbage collection time.
447
448           FGC: Number of full GC events.
449
450           FGCT: Full garbage collection time.
451
452           GCT: Total garbage collection time.
453
454       -printcompilation option
455           Java HotSpot VM compiler method statistics.
456
457           Compiled: Number of compilation tasks performed by the most
458           recently compiled method.
459
460           Size: Number of bytes of byte code of the most recently compiled
461           method.
462
463           Type: Compilation type of the most recently compiled method.
464
465           Method: Class name and method name identifying the most recently
466           compiled method. Class name uses slash (/) instead of dot (.) as a
467           name space separator. Method name is the method within the
468           specified class. The format for these two fields is consistent with
469           the HotSpot -XX:+PrintCompilation option.
470

EXAMPLES

472       This section presents some examples of monitoring a local JVM with an
473       lvmid of 21891.
474
475   The gcutil Option
476       This example attaches to lvmid 21891 and takes 7 samples at 250
477       millisecond intervals and displays the output as specified by the
478       -gcutil option.
479
480       The output of this example shows that a young generation collection
481       occurred between the third and fourth sample. The collection took 0.078
482       seconds and promoted objects from the eden space (E) to the old space
483       (O), resulting in an increase of old space utilization from 66.80% to
484       68.19%. Before the collection, the survivor space was 97.02% utilized,
485       but after this collection it is 91.03% utilized.
486
487           jstat -gcutil 21891 250 7
488             S0     S1     E      O      M     CCS    YGC     YGCT    FGC    FGCT     GCT
489             0.00  97.02  70.31  66.80  95.52  89.14      7    0.300     0    0.000    0.300
490             0.00  97.02  86.23  66.80  95.52  89.14      7    0.300     0    0.000    0.300
491             0.00  97.02  96.53  66.80  95.52  89.14      7    0.300     0    0.000    0.300
492            91.03   0.00   1.98  68.19  95.89  91.24      8    0.378     0    0.000    0.378
493            91.03   0.00  15.82  68.19  95.89  91.24      8    0.378     0    0.000    0.378
494            91.03   0.00  17.80  68.19  95.89  91.24      8    0.378     0    0.000    0.378
495            91.03   0.00  17.80  68.19  95.89  91.24      8    0.378     0    0.000    0.378
496
497   Repeat the Column Header String
498       This example attaches to lvmid 21891 and takes samples at 250
499       millisecond intervals and displays the output as specified by -gcnew
500       option. In addition, it uses the -h3 option to output the column header
501       after every 3 lines of data.
502
503       In addition to showing the repeating header string, this example shows
504       that between the second and third samples, a young GC occurred. Its
505       duration was 0.001 seconds. The collection found enough active data
506       that the survivor space 0 utilization (S0U) would have exceeded the
507       desired survivor Size (DSS). As a result, objects were promoted to the
508       old generation (not visible in this output), and the tenuring threshold
509       (TT) was lowered from 31 to 2.
510
511       Another collection occurs between the fifth and sixth samples. This
512       collection found very few survivors and returned the tenuring threshold
513       to 31.
514
515           jstat -gcnew -h3 21891 250
516            S0C    S1C    S0U    S1U   TT MTT  DSS      EC       EU     YGC     YGCT
517             64.0   64.0    0.0   31.7 31  31   32.0    512.0    178.6    249    0.203
518             64.0   64.0    0.0   31.7 31  31   32.0    512.0    355.5    249    0.203
519             64.0   64.0   35.4    0.0  2  31   32.0    512.0     21.9    250    0.204
520            S0C    S1C    S0U    S1U   TT MTT  DSS      EC       EU     YGC     YGCT
521             64.0   64.0   35.4    0.0  2  31   32.0    512.0    245.9    250    0.204
522             64.0   64.0   35.4    0.0  2  31   32.0    512.0    421.1    250    0.204
523             64.0   64.0    0.0   19.0 31  31   32.0    512.0     84.4    251    0.204
524            S0C    S1C    S0U    S1U   TT MTT  DSS      EC       EU     YGC     YGCT
525             64.0   64.0    0.0   19.0 31  31   32.0    512.0    306.7    251    0.204
526
527
528   Include a Time Stamp for Each Sample
529       This example attaches to lvmid 21891 and takes 3 samples at 250
530       millisecond intervals. The -t option is used to generate a time stamp
531       for each sample in the first column.
532
533       The Timestamp column reports the elapsed time in seconds since the
534       start of the target JVM. In addition, the -gcoldcapacity output shows
535       the old generation capacity (OGC) and the old space capacity (OC)
536       increasing as the heap expands to meet allocation or promotion demands.
537       The old generation capacity (OGC) has grown from 11,696 kB to 13,820 kB
538       after the eighty-first full garbage collection (FGC). The maximum
539       capacity of the generation (and space) is 60,544 kB (OGCMX), so it
540       still has room to expand.
541
542           Timestamp      OGCMN    OGCMX     OGC       OC       YGC   FGC    FGCT    GCT
543                     150.1   1408.0  60544.0  11696.0  11696.0   194    80    2.874   3.799
544                     150.4   1408.0  60544.0  13820.0  13820.0   194    81    2.938   3.863
545                     150.7   1408.0  60544.0  13820.0  13820.0   194    81    2.938   3.863
546
547
548   Monitor Instrumentation for a Remote JVM
549       This example attaches to lvmid 40496 on the system named remote.domain
550       using the -gcutil option, with samples taken every second indefinitely.
551
552       The lvmid is combined with the name of the remote host to construct a
553       vmid of 40496@remote.domain. This vmid results in the use of the rmi
554       protocol to communicate to the default jstatd server on the remote
555       host. The jstatd server is located using the rmiregistry command on
556       remote.domain that is bound to the default port of the rmiregistry
557       command (port 1099).
558
559           jstat -gcutil 40496@remote.domain 1000
560           ... output omitted
561
562

SEE ALSO

564       ·   java(1)
565
566       ·   jps(1)
567
568       ·   jstatd(1)
569
570       ·   rmiregistry(1)
571
572
573
574JDK 8                            03 March 2015                        jstat(1)