jstat命令

jstat命令的格式如下：

jstat [-options] [vmid] [间隔时间/毫秒] [查询次数]

常见的options有：

l class (类加载器)

l compiler (JIT)

l gc (GC堆状态)

l gccapacity (各区大小)

l gccause (最近一次GC统计和原因)

l gcnew (新区统计)

l gcnewcapacity (新区大小)

l gcold (老区统计)

l gcoldcapacity (老区大小)

l gcpermcapacity (永久区大小)

l gcutil (GC统计汇总)

l printcompilation (HotSpot编译统计)

1.jstat -gcutil

[sre@CDM1E03-209010065 ~]$ jstat -gcutil 9956

S0     S1     E      O      P     YGC     YGCT    FGC    FGCT     GCT

22.61   0.00  84.75  12.57  99.62    282    5.876     0    0.000    5.876

name	desc
S0	SURVIVOR0 space使用百分比
S1	SURVIVOR1 space使用百分比
E	Eden space使用百分比
O	Old space使用百分比
P	Permanent space使用百分比
YGCT	Number of young generation GC events
FGC	Young generation garbage collection time
FGCT	Number of full GC events
FGCT	Full garbage collection time
GCT	Total garbage collection time

2.jstat -gc

[sre@CDM1E03-209010065 ~]$ jstat -gc 9956

S0C    S1C    S0U    S1U      EC       EU        OC         OU       PC     PU    YGC     YGCT    FGC    FGCT     GCT

27136.0 27648.0  0.0   6352.0 992768.0 185532.0 2097152.0   264019.0  63488.0 63246.4    283    5.892   0      0.000    5.892

name	desc
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	Current eden space capacity (KB)
OC	Current old space capacity (KB)
OU	Old space utilization (KB)
PC	Current permanent space capacity (KB)
PU	Permanent space utilization (KB)
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

3.jstat -gccapacity

[sre@CDM1E03-209010065 ~]$ jstat -gccapacity 9956

NGCMN    NGCMX     NGC     S0C   S1C       EC      OGCMN      OGCMX       OGC         OC      PGCMN    PGCMX     PGC       PC     YGC    FGC

1048576.0 1048576.0 1048576.0 27136.0 27648.0 992768.0  2097152.0  2097152.0  2097152.0  2097152.0  21504.0  83968.0  63488.0  63488.0    283     0

name	desc
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)
OG	Current old space capacity (KB)
PGCMN	Minimum permanent generation capacity (KB)
PGCMX	Maximum Permanent generation capacity (KB)
PGC	Current Permanent generation capacity (KB)
PG	Current Permanent space capacity (KB)
YGC	Number of Young generation GC Events
FGC	Number of Full GC Events

4.jstat -gccause

[sre@CDM1E03-209010065 ~]$ jstat -gccause 9956

S0     S1     E      O      P     YGC     YGCT    FGC    FGCT     GCT    LGCC                 GCC

0.00  22.97  91.12  12.59  99.62    283    5.892     0    0.000    5.892 Allocation Failure   No GC

-gccause与-gcutil相比，多展示了两列

name	desc
LGCC	Cause of last Garbage Collection
GCC	Cause of current Garbage Collection

5.jstat -gcnew

[sre@CDM1E03-209010065 ~]$ jstat -gcnew 9956

S0C    S1C    S0U    S1U   TT MTT  DSS      EC       EU     YGC     YGCT

27136.0 26624.0 6827.0    0.0  1  15 26624.0 994816.0  44565.8    284    5.910

name	desc
TT	Tenuring threshold
MTT	Maximum tenuring threshold
DSS	Desired survivor size (KB)

6.jstat -gcnewcapacity

7.jstat -gcold

8.jstat -gcoldcapacity

9.jstat -gcpermcapacity