Java command simple view JVM memory usage

Java command simple view JVM memory usage

1. JPS Virtual machine process Status Tool

Syntax jsp [option] [HostID]

Options

Role

-Q

Show Only Lvmid

-M

Pass in Main method parameter when output virtual machine is enabled

-L

Output main class full Name

-V

Output JVM Parameters

Attention:

If the JPS command cannot output vmid data (jdk1.6.0.23/24 bug) in a Linux environment, the catalina.sh file needs to be modified

If [-Z "$CATALINA _tmpdir"]; then?# Define the Java.io.tmpdir to use for catalina?# catalina_tmpdir= "$CATALINA _base"/temp? Catalina_tmpdir=/tmp?fi

Modifying the Catalina_tmpdir Path

2, Jstat virtual machine statistical information monitoring tool

Grammar:

jstat [Option Vmid [Interval[s|ms]] [count]]

Option options

Class

Statistics class loader behavior information

Compiler

Statistical compilation Behavior Information

Gc

Statistics JDK GC time heap information

Gccapacity

Heap capacity information for the different generations of the statistics stack memory

Gccause

Statistics GC (same-gcutil) and events that cause GC

Gcnew

Statistics of the new generation of GC (more detailed than Gcutil)

Gcnewcapacity

New generation heap capacity in GC statistics

Gcold

When statistics GC, the situation of the old age area

Gcoldcapacity

When statistics GC, the old area heap capacity

Gcpermcapacity

When statistics GC, permanent area heap capacity

Gcutil

When statistics GC, the heap condition

Printcompilation

Statistical compilation Behavior Information

For example:

JSTAT-GC 1111 250 2

View virtual machines with a vmid of 1111 executed every 250 milliseconds, twice in total

Results analysis

-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.

The preceding fields are the same as gcutil.

-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, consistent, and the hotspot-xx:+printcomplation option.

Java command simple view JVM memory usage