문제를 잘 정의하는 것은 문제를 절반 해결한 것이다. - 2023.12

JVM 프로세스 목록을 확인할 수 있음

$> jps -v
32128 Jps -Dapplication.home=/PROJECT/dge.repia.com/SearchApp/jdk1.8.0_202 -Xms8m
5287 Server
24487 Bootstrap -Djava.util.logging.config.file=/WAS_APPS/tomcat-instance/kigam.repia.com/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.awt.headless=true -Xms512m -Xmx1024m -XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=256m -XX:MaxPermSize=512m -XX:+DisableExplicitGC -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Denv=product -Denv.servername=kigam.repia.com -Dignore.endorsed.dirs= -Dcatalina.base=/WAS_APPS/tomcat-instance/kigam.repia.com -Dcatalina.home=/WAS_APPS/apache-tomcat-8.5.76 -Djava.io.tmpdir=/WAS_APPS/tomcat-instance/kigam.repia.com/temp
22156 Bootstrap -Djava.util.logging.config.file=/WAS_APPS/tomcat-instance/dge.repia.com/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.awt.headless=true -Xms512m -Xmx1024m -XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=256m -XX:MaxPermSize=512m -XX:+DisableExplicitGC -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Denv=product -Denv.servername=dge.repia.com -Dignore.endorsed.dirs= -Dcatalina.base=/WAS_APPS/tomcat-instance/dge.repia.com -Dcatalina.home=/WAS_APPS/apache-tomcat-8.5.76 -Djava.io.tmpdir=/WAS_APPS/tomcat-instance/dge.repia.com/temp
26732 Server
27185 jar
14770 Server
26132 jar
18037 Server
20021 jar
25242 Bootstrap -Djava.util.logging.config.file=/usr/local/tomcat8/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= -Dcatalina.base=/usr/local/tomcat8 -Dcatalina.home=/usr/local/tomcat8 -Djava.io.tmpdir=/usr/local/tomcat8/temp
32412 jar
11933 jar
26878 Bootstrap -Djava.util.logging.config.file=/WAS_APPS/tomcat-instance/centos79.repia.com/conf/logging.properties -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.awt.headless=true -Xms512m -Xmx1024m -XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=256m -XX:MaxPermSize=512m -XX:+DisableExplicitGC -Djdk.tls.ephemeralDHKeySize=2048 -Djava.protocol.handler.pkgs=org.apache.catalina.webresources -Dorg.apache.catalina.security.SecurityListener.UMASK=0027 -Denv=product -Denv.servername=centos79.repia.com -Dignore.endorsed.dirs= -Dcatalina.base=/WAS_APPS/tomcat-instance/centos79.repia.com -Dcatalina.home=/WAS_APPS/apache-tomcat-8.5.76 -Djava.io.tmpdir=/WAS_APPS/tomcat-instance/centos79.repia.com/temp

현재 실행 중인 JVM 프로세스의 메모리 맵(map)을 확인할 수 있음
JVM의 힙 메모리 정보를 얻어오거나 덤프를 떠서 분석해 볼 수 있다.

<code bash> $> jmap -heap 200021 [root@sofo dump]# /PROJECT/dge.repia.com/SearchApp/java8/bin/jmap -heap 20021 Attaching to process ID 20021, please wait… Debugger attached successfully. Server compiler detected. JVM version is 25.202-b08

using thread-local object allocation. Parallel GC with 8 thread(s)

Heap Configuration:

 MinHeapFreeRatio         = 0
 MaxHeapFreeRatio         = 100
 MaxHeapSize              = 2009071616 (1916.0MB)
 NewSize                  = 41943040 (40.0MB)
 MaxNewSize               = 669515776 (638.5MB)
 OldSize                  = 83886080 (80.0MB)
 NewRatio                 = 2
 SurvivorRatio            = 8
 MetaspaceSize            = 21807104 (20.796875MB)
 CompressedClassSpaceSize = 1073741824 (1024.0MB)
 MaxMetaspaceSize         = 17592186044415 MB
 G1HeapRegionSize         = 0 (0.0MB)

Heap Usage: PS Young Generation Eden Space:

 capacity = 125829120 (120.0MB)
 used     = 41686504 (39.755348205566406MB)
 free     = 84142616 (80.2446517944336MB)
 33.12945683797201% used

From Space:

 capacity = 5242880 (5.0MB)
 used     = 5231912 (4.989540100097656MB)
 free     = 10968 (0.01045989990234375MB)
 99.79080200195312% used

To Space:

 capacity = 5242880 (5.0MB)
 used     = 0 (0.0MB)
 free     = 5242880 (5.0MB)
 0.0% used

PS Old Generation

 capacity = 83886080 (80.0MB)
 used     = 6313904 (6.0214080810546875MB)
 free     = 77572176 (73.97859191894531MB)
 7.526760101318359% used

1711 interned Strings occupying 144344 bytes.

JVM 메모리 통계 $> jmap -F -histo 20021 메모리 덤프 $> jmap -F -dump:format=b,file=heap.hprof 20021

메모리 덤프 파일 분석 <code bash> $> jhat heap.hprof -port 7000 </code

• [Java] 자바 메모리 덤프 분석 - jps, jmap, jhat 사용법 및 예제
• [Java] Heap 모니터링 & Heap Dump 분석하기