JVM监控功能工具jstat的使用
格式
jstat [ generalOption | outputOptions vmid [interval[s|ms] [count]] ]
GeneralOption
-help：显示帮助信息
-version：显示版本
-options：显示所有的statOption
如果指定了generalOption, 那么就不能再指定outputOptions了
OutputOption
格式：[ statOption [ -t | -h | -J ]
-t：输出结果加上timestamp列，值为自jvm启动的时长(秒)
-h n：每输出n行数据就输出一行头信息，用于多次输出时
-JjavaOption：Passes javaOption to the Java application launcher. For example, -J-Xms48m sets the startup memory to 48 MB. For a complete list of options
outputOption决定输出的内容以及格式, 由statOption和otherOutputOption（-t, -h, -J）组成, statOption必须放在前面
StatOption
-class
显示class loader的信息
Loaded：已加载的类个数
Bytes：已加载字节（Kbytes，千字节）
Unloaded：已卸载的类个数
Bytes：已卸载字节（Kbytes，千字节）
Time：用于类加载及卸载所用的总时间
-compiler
显示JIT的统计信息
Compiled：Number of compilation tasks performed
Failed：Number of compilation tasks that 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 for the last failed compilation
-gc
显示垃圾回收统计信息（堆）
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
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
显示堆内存相关信息
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.
-gcutil
显示垃圾回收相关信息
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.
-gccause
类似于-gcutil，多了LGCC和GCC
LGCC: Cause of last garbage collection
GCC: Cause of current garbage collection
-gcnew
显示新生代统计信息
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
新生代空间大小统计信息
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
老年代及方法区的统计信息
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
老年代容量信息
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
方法区容量信息
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.
-printcompilation
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.
示例用法
1.jstat -gcutil -t -h 2 6300 1s 10
