Tomcat性能优化_查看堆内存分配情况-【官方】百战程序员_IT在线教育培训机构

windows下查看tomcat堆内存
以jdk1.8为例
step1：把C:\Program Files (x86)\Java\jdk1.8.0_291\jre\bin目录下的sawindbg.dll，拷贝到C:\Program Files (x86)\Java\jre1.8.0_291\bin目录下

step2：打开powershell，在此目录下执行


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C:\Program Files (x86)\Java\jdk1.8.0_291\lib> java -cp .\sa-jdi.jar sun.jvm.hotspot.HSDB

step3：此时出现

选择Tools菜单下的Heap Parameters菜单

在linux下查看tomcat的堆内存分配情况
首先查看tomcat的pid


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[root@192 bin]# ps aux|grep tomcat
root      17109 13.8  3.6 3167980 140048 pts/4  Sl   11:36   0:07 /usr/local/jdk-11.0.11//bin/java -Djava.util.logging.config.file=/usr/local/apache-tomcat-9.0.64/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Dignore.endorsed.dirs= -classpath /usr/local/apache-tomcat-9.0.64/bin/bootstrap.jar:/usr/local/apache-tomcat-9.0.64/bin/tomcat-juli.jar -Dcatalina.base=/usr/local/apache-tomcat-9.0.64 -Dcatalina.home=/usr/local/apache-tomcat-9.0.64 -Djava.io.tmpdir=/usr/local/apache-tomcat-9.0.64/temp org.apache.catalina.startup.Bootstrap start
root      17238  0.0  0.0 112808   968 pts/4    R+   11:37   0:00 grep --color=auto tomcat

使用jhsdb命令查看内存分配情况


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[root@192 bin]# jhsdb jmap --heap --pid 17109
Attaching to process ID 17109, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 11.0.11+9-LTS-194

using thread-local object allocation.
Mark Sweep Compact GC

Heap Configuration:
   MinHeapFreeRatio         = 40
   MaxHeapFreeRatio         = 70
   MaxHeapSize              = 989855744 (944.0MB)
   NewSize                  = 20971520 (20.0MB)
   MaxNewSize               = 329908224 (314.625MB)
   OldSize                  = 41943040 (40.0MB)
   NewRatio                 = 2
   SurvivorRatio            = 8
   MetaspaceSize            = 21807104 (20.796875MB)
   CompressedClassSpaceSize = 1073741824 (1024.0MB)
   MaxMetaspaceSize         = 17592186044415 MB
   G1HeapRegionSize         = 0 (0.0MB)

Heap Usage:
New Generation (Eden + 1 Survivor Space):
   capacity = 18939904 (18.0625MB)
   used     = 14369232 (13.703567504882812MB)
   free     = 4570672 (4.3589324951171875MB)
   75.86750175713668% used
Eden Space:
   capacity = 16842752 (16.0625MB)
   used     = 12400880 (11.826400756835938MB)
   free     = 4441872 (4.2360992431640625MB)
   73.62739770792801% used
From Space:
   capacity = 2097152 (2.0MB)
   used     = 1968352 (1.877166748046875MB)
   free     = 128800 (0.122833251953125MB)
   93.85833740234375% used
To Space:
   capacity = 2097152 (2.0MB)
   used     = 0 (0.0MB)
   free     = 2097152 (2.0MB)
   0.0% used
tenured generation:
   capacity = 41943040 (40.0MB)
   used     = 16412096 (15.65179443359375MB)
   free     = 25530944 (24.34820556640625MB)
   39.129486083984375% used

实时效果反馈

1.调整jvm的哪个参数对优化tomcat性能有帮助？

A -server

B -Xms（最小堆内存）

C -Xmx（最大堆内存）

D 以上都是

答案

1=>D

Tomcat性能优化_jvm垃圾收集参数设定 Tomcat性能优化_Jmeter简介

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