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java 命令简单查看jvm内存使用状况
1、jps 虚拟机进程状况工具
语法 jsp [option] [hostid]
选项
作用
-q
只显示lvmid
-m
输出虚拟机启用时传入main方法参数
-l
输出主类全名
-v
输出jvm参数
注意：
如果在linux环境中jps命令不能输出vmid数据（jdk1.6.0.23/24 bug），需要修改catalina.sh文件
if [ -z "$CATALINA_TMPDIR" ] ; then?# Define the java.io.tmpdir to use for Catalina?# CATALINA_TMPDIR="$CATALINA_BASE"/temp?CATALINA_TMPDIR=/tmp?fi
修改CATALINA_TMPDIR路径
2、jstat 虚拟机统计信息监控工具
语法：
jstat [option vmid [interval[s|ms]] [count]]
option选项
class
统计class loader行为信息
compiler
统计编译行为信息
gc
统计jdk gc时heap信息
gccapacity
统计堆内存不同代的heap容量信息
gccause
统计gc的情况（同-gcutil）和引起gc的事件
gcnew
统计gc时新生代的信息(相比gcutil更详细)
gcnewcapacity
统计gc时新生代heap容量
gcold
统计gc时，老年区的情况
gcoldcapacity
统计gc时，老年区heap容量
gcpermcapacity
统计gc时，permanent区heap容量
gcutil
统计gc时，heap情况
printcompilation
统计编译行为信息
例如：
jstat -gc 1111 250 2
查看vmid为1111的虚拟机每个250毫秒执行一次，共执行两次
结果分析
-class option:Class Loader Statistics
ColumnDescription
Loaded
Number of classes loaded.
Bytes
Number of Kbytes loaded.
Unloaded
Number of classes unloaded.
Bytes
Number of Kbytes unloaded.
Time
Time spent performing class load and unload operations.
-compiler:HotSpot Just-In-Time Compiler Statistics
ColumnDescription
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 Option:Garbage-collected heap statistics
ColumnDescription
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).
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.
-gccapacity Option:Memory Pool Generation and Space Capacities
ColumnDescription
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).
PGCMN
Minimum permanent generation capacity (KB).
PGCMX
Maximum Permanent generation capacity (KB).
PGC
Current Permanent generation capacity (KB).
PC
Current Permanent space capacity (KB).
YGC
Number of Young generation GC Events.
FGC
Number of Full GC Events.
-gccause Option:Garbage Collection Statistics, Including GC Events
ColumnDescription
LGCC
Cause of last Garbage Collection.
GCC
Cause of current Garbage Collection.
前面的字段与gcutil相同.
-gcnew Option:New Generation Statistics
ColumnDescription
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 Option:New Generation Space Size Statistics
ColumnDescription
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 Option:Old and Permanent Generation Statistics
ColumnDescription
PC
Current permanent space capacity (KB).
PU
Permanent space utilization (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 Option:Old Generation Statistics
ColumnDescription
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.
-gcpermcapacity Option: Permanent Generation Statistics
ColumnDescription
PGCMN
Minimum permanent generation capacity (KB).
PGCMX
Maximum permanent generation capacity (KB).
PGC
Current permanent generation capacity (KB).
PC
Current permanent 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.
-gcutil Option:Summary of Garbage Collection Statistics
ColumnDescription
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.
P
Permanent space utilization as a percentage of the space‘s current capacity.
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.
-printcompilation Option: HotSpot Compiler Method Statistics
ColumnDescription
Compiled
Number of compilation tasks performed.
Size
Number of bytes of bytecode for the method.
Type
Compilation type.
Method
Class name and method name identifying the compiled method. Class name uses "/" instead of "." as namespace separator. Method name is the method within the given class. The format for these two fields is consistent with the HotSpot -XX:+PrintComplation option.
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原文地址：http://my.oschina.net/phacks/blog/423785
