JVM監控功能工具jstat的使用
格式
jstat [ generalOption | outputOptions vmid [interval[s|ms] [count]] ]
GeneralOption
-help：顯示幫助信息
-version：顯示版本
-options：顯示所有的statOption
如果指定了generalOption, 那麼就不能再指定outputOptions了
OutputOption
格式：[ statOption [ -t | -h | -J ]
-t：輸出結果加上timestamp列，值爲自jvm啓動的時長(秒)
-h n：每輸出n行數據就輸出一行頭信息，用於多次輸出時
-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決定輸出的內容以及格式, 由statOption和otherOutputOption（-t, -h, -J）組成, statOption必須放在前面
StatOption
-class
顯示class loader的信息
Loaded：已加載的類個數
Bytes：已加載字節（Kbytes，千字節）
Unloaded：已卸載的類個數
Bytes：已卸載字節（Kbytes，千字節）
Time：用於類加載及卸載所用的總時間
-compiler
顯示JIT的統計信息
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
顯示垃圾回收統計信息（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
顯示堆內存相關信息
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
顯示垃圾回收相關信息
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
類似於-gcutil，多了LGCC和GCC
LGCC: Cause of last garbage collection
GCC: Cause of current garbage collection
-gcnew
顯示新生代統計信息
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
新生代空間大小統計信息
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
老年代及方法區的統計信息
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
方法區容量信息
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
