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java 命令容易查看jvm内存使用状况

分类: IT文章 • 2022-05-22 17:25:21
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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