Java 어플리케이션 성능튜닝 Part1

Java 어플리케이션 성능튜닝 Part1

• 1.
  어플리케이션 성능튜닝 교육 지앤클라우드송상욱
• 2.
  성능측정 고려사항: TPS (Transaction/ Throughput) 1. CPU 사용률이 높다 => 코드 리팩토링 2. CPU 사용률이 낮다 => 블로킹 ( 쓰레드 / IO ) 3. 메모리 사용률이 높다. a. OOM발생 => 메모리릭 b. GC가 빈번 => 코드 리팩토링 (메모리 재사용) c. Full GC 시 어플리케이션 정지 i. 메모리를 높인다. ii. 메모리를 낮춘다. iii. GC 종류를 변경한다.
• 3.
  자바(톰캣) 성능튜닝 고려사항 1.memory usage 2. garbage collection 3. thread usage 4. request throughout 5. number of sessions 6. response time 7. database connection pool 8. error rates 9. uptime
• 4.
  GC
• 5.
  가비지컬렉션 프로세스 https://www.oracle.com/webfolder/technetwork/tutorials/obe/java/gc01/index.html > DescribingGarbage Collection > The Generational Garbage Collection Process
• 6.
  G1GC ● MaxGCPauseMillis 플래그로G1의 일시 중지 시간 목표를 설정 ● G1은 예측 모델을 사용하여 해당 목표 일시 중지 시간 내에 가비지 수집 작업의 양을 결정 ● 컬렉션이 끝나면 G1은 다음 컬렉션 (컬렉션 집합)에서 수집 할 영역을 선택 ● MaxGCPauseMillis의 기본값은 200 밀리 초
• 7.
  -XX:- UseConcMarkSweepGC Use concurrent mark-sweepcollection for the old generation. (Introduced in 1.4.1) - XX:+UseGCOverheadLimit Use a policy that limits the proportion of the VM's time that is spent in GC before an OutOfMemory error is thrown. (Introduced in 6.) - XX:+UseLWPSynchronizati on Use LWP-based instead of thread based synchronization. (Introduced in 1.4.0. Relevant to Solaris only.) -XX:-UseParallelGC Use parallel garbage collection for scavenges. (Introduced in 1.4.1) -XX:-UseParallelOldGC Use parallel garbage collection for the full collections. Enabling this option automatically sets -XX:+UseParallelGC. (Introduced in 5.0 update 6.) -XX:-UseSerialGC Use serial garbage collection. (Introduced in 5.0.) Java -XX GC Options
• 8.
  Option and DefaultValue Description -XX:+UseG1GC Use the Garbage First (G1) Collector -XX:MaxGCPauseMillis=n Sets a target for the maximum GC pause time. This is a soft goal, and the JVM will make its best effort to achieve it. -XX:InitiatingHeapOccupancyPercent=n Percentage of the (entire) heap occupancy to start a concurrent GC cycle. It is used by GCs that trigger a concurrent GC cycle based on the occupancy of the entire heap, not just one of the generations (e.g., G1). A value of 0 denotes 'do constant GC cycles'. The default value is 45. -XX:NewRatio=n Ratio of old/new generation sizes. The default value is 2. -XX:SurvivorRatio=n Ratio of eden/survivor space size. The default value is 8. -XX:MaxTenuringThreshold=n Maximum value for tenuring threshold. The default value is 15. -XX:ParallelGCThreads=n Sets the number of threads used during parallel phases of the garbage collectors. The default value varies with the platform on which the JVM is running. -XX:ConcGCThreads=n Number of threads concurrent garbage collectors will use. The default value varies with the platform on which the JVM is running. -XX:G1ReservePercent=n Sets the amount of heap that is reserved as a false ceiling to reduce the possibility of promotion failure. The default value is 10. -XX:G1HeapRegionSize=n With G1 the Java heap is subdivided into uniformly sized regions. This sets the size of the individual sub-divisions. The default value of this parameter is determined ergonomically based upon heap size. The minimum value is 1Mb and the maximum value is 32Mb.
• 9.
  Command Options* ResultingCollector Combination -XX:+UseSerialGC young Copy and old MarkSweepCompact -XX:+UseG1GC young G1 Young and old G1 Mixed -XX:+UseParallelGC -XX:+UseParallelOldGC -XX:+UseAdaptiveSizePolicy young PS Scavenge old PS MarkSweep with adaptive sizing -XX:+UseParallelGC -XX:+UseParallelOldGC -XX:-UseAdaptiveSizePolicy young PS Scavenge old PS MarkSweep, no adaptive sizing -XX:+UseParNewGC (deprecated in Java 8 and removed in Java 9 - for ParNew see the line below which is NOT deprecated) young ParNew old MarkSweepCompact -XX:+UseConcMarkSweepGC -XX:+UseParNewGC young ParNew old ConcurrentMarkSweep** -XX:+UseConcMarkSweepGC -XX:-UseParNewGC (deprecated in Java 8 and removed in Java 9) young Copy old ConcurrentMarkSweep** *All the combinations listed here will fail to let the JVM start if you add another GC algorithm not listed, with the exception of -XX:+UseParNewGC which is only combinable with -XX:+UseConcMarkSweepGC Combinations of Garbage Collectors
• 10.
  -XX:HeapDumpPath=./java_pid<pid>.hprof Path todirectory or filename for heap dump. Manageable. (Introduced in 1.4.2 update 12, 5.0 update 7.) -XX:-HeapDumpOnOutOfMemoryError Dump heap to file when java.lang.OutOfMemoryError is thrown. Manageable. (Introduced in 1.4.2 update 12, 5.0 update 7.) -XX:OnError="<cmd args>;<cmd args>" Run user-defined commands on fatal error. (Introduced in 1.4.2 update 9.) -XX:OnOutOfMemoryError="<cmd args>; <cmd args>" Run user-defined commands when an OutOfMemoryError is first thrown. (Introduced in 1.4.2 update 12, 6) -XX:-PrintClassHistogram Print a histogram of class instances on Ctrl-Break. Manageable. (Introduced in 1.4.2.) The jmap -histo command provides equivalent functionality. -XX:-PrintConcurrentLocks Print java.util.concurrent locks in Ctrl-Break thread dump. Manageable. (Introduced in 6.) The jstack -l command provides equivalent functionality. -XX:-PrintCommandLineFlags Print flags that appeared on the command line. (Introduced in 5.0.) -XX:-PrintCompilation Print message when a method is compiled. -XX:-PrintGC Print messages at garbage collection. Manageable. -XX:-PrintGCDetails Print more details at garbage collection. Manageable. (Introduced in 1.4.0.) -XX:-PrintGCTimeStamps Java -XX Debugging Options
• 11.
  Tomcat
• 12.
  톰캣 Server.xml ● connectionTimeout="5000"- 기본 20초로 설정됨. ● keepAliveTimeout=”5000” - 기본 connectionTimeout 과 동일하게 설정됨. ● minSpareThreads="25" - 항상 실행되는 최소 스레드 수 ● maxThreads="200" - 작업스레드 수 ● acceptCount="100" - 요청 큐 최대길이 ● disableUploadTimeout="true" ● maxConnections="8192" - 최대연결 ● enableLookups=”false” - DNS lookup ● compression="off" - 메시지 압축 ● tcpNoDelay="true" - 버퍼가 차기전에 바로 전송 https://tomcat.apache.org/tomcat-8.5-doc/config/http.html
• 13.
  종류 옵션 동작모드 -server 전체힙 크기 -Xms와 - Xmx의 값을 동일하게 설정 New 영역 크기 -XX:NewRatio 2~4 정도의 값 Perm 크기 -XX:NewSize -XX:MaxNewSize -XX:PermSize=256m -XX:MaxPermSize=256m 성능에 영향을 미치지 않으므로 동작에 문제가 없을 정도만 지정 GC 로그 -Xloggc:$CATALINA_HOME/logs/gc.log -XX:+PrintGCDetails -XX:+PrintGCDateStamps OOM 에러 발생 시 힙 덤프 생성 -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=$CATALINA_HOME/logs OOM 발생 이후 조치 -XX:OnOutOfMemoryError=$CATALINA_HOME/bin/stop.sh -XX:OnOutOfMemoryError=$CATALINA_HOME/bin/restart.sh 톰캣 VM Options
• 14.
  디버깅
• 15.
  JDWP java -Xdebug - Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=yTest 옵션 : - transport=dt_shmem (using shared memory). 동일머신에서만 사용가능. JDWP = Java Debug Wire Protocol
• 16.
  Java tools
• 17.
  Standard JDK Toolsand Utilities ● Basic Tools (appletviewer, extcheck, jar, java, javac, javadoc, javah, javap, jdb, jdeps) ● Security Tools (keytool, jarsigner, policytool, kinit, klist, ktab) ● Internationalization Tools (native2ascii) ● Remote Method Invocation (RMI) Tools (rmic, rmiregistry, rmid, serialver) ● Java IDL and RMI-IIOP Tools (tnameserv, idlj, orbd, servertool) ● Java Deployment Tools (javapackager, pack200, unpack200) ● Java Web Start Tools (javaws) ● Java Troubleshooting, Profiling, Monitoring and Management Tools (jcmd, jconsole, jmc, jvisualvm) ● Java Web Services Tools (schemagen, wsgen, wsimport, xjc) ● Monitoring Tools (jps, jstat, jstatd) ● Troubleshooting Tools (jinfo, jhat, jmap, jsadebugd, jstack)
• 18.
  HPROF profiler Writes classprofiling information to a file or a socket, in ASCII or binary. ● Heap allocation profiling. ● Heap dump. ● CPU usage - for threads, methods. ● Monitor contention profiling. To invoke the HPROF tool: java -agentlib:hprof ToBeProfiledClass To print the complete list of options: java -agentlib:hprof=help
• 19.
  jhat Parse a binaryheap dump, launch a web browser, and present standard queries. ● Execute standard queries, for example, classes, objects, class instances, reference chains from object rootset, reachable objects, and more. ● Turn on or off object allocation tracking. ● Turn on or off object reference tracking. ● Specify objects to exclude from "reachable objects" query. ● Pass flags to the Java VM on which jhat is running. ● Develop custom queries with buit-in Object Query Language. ● Compare objects in two dumps.
• 20.
  jmap ● Print sharedobject mappings for a process, a core file, or a remote debug server. ● Dump the Java heap (all objects or only live objects) of a process, a core file, or a remote debug server in binary format to a file. ● Force the Java heap dump of a process if the process does not respond. ● Print a heap summary for a process, a core file, or a remote debug server. ● Print a histogram (all objects or only live objects) of a process, a core file, or a remote debug server. ● Print information on objects awaiting finalization. ● Print class loader statistics of the permanent generation. ● Pass flags to the VM
• 21.
  jstack ● Print stacktraces of threads for a process, core file, or remote debug server ● Print information about concurrent locks for a process, core file, or remote debug server ● Force the stack dump for a process if the process does not respond
• 22.
  jstat jstat -gc -h1015994 1000 Monitors Java Virtual Machine (JVM) statistics. -class -compiler -gc -gccapacity -gccause -gcmetacapacity -gcnew -gcnewcapacity -gcold -gcoldcapacity -gcutil -printcompilation
• 23.
  jvisualvm https://htmlpreview.github.io/?https://raw.githubusercontent.com/visualvm/visualvm.java.net.ba ckup/master/www/ko_KR/gettingstarted.html
• 24.
  패스트캣 쉘스크립트
• 25.
  fastcatsearch.sh #!/bin/bash [...중략..] # PROFILE PROFILE_AGENT_LINUX_X86_32=$server_home/bin/profile/yourkit/bin/linux-x86- 32/libyjpagent.so PROFILE_AGENT_LINUX_X86_64=$server_home/bin/profile/yourkit/bin/linux-x86- 64/libyjpagent.so PROFILE_AGENT_WIN32=$server_home/bin/profile/yourkit/bin/win32/yjpagent.dll PROFILE_AGENT_WIN64=$server_home/bin/profile/yourkit/bin/win64/yjpagent.dll PROFILE_AGENT=PROFILE_AGENT_LINUX_X86_64 PROFILE_PORT=10001
• 26.
  fastcatsearch.sh (이어서) JVM_OPTS="-Xms$heap_memory_size -Xmx$heap_memory_size-XX:+HeapDumpOnOutOfMemoryError" JAVA_OPTS="-server -Dorg.jboss.netty.epollBugWorkaround=true -Dfile.encoding=UTF-8 - Dlogback.configurationFile=$CONF/logback.xml -Dderby.stream.error.file=$LOGS/db.log - Duser.timezone=Asia/Seoul" DEBUG_OPT="-agentlib:jdwp=transport=dt_socket,suspend=n,server=y,address=59090" PROFILE_OPT_JMX="-verbosegc -XX:+PrintGCDetails -Dcom.sun.management.jmxremote" PROFILE_OPT="-agentpath:$PROFILE_AGENT=port=$PROFILE_PORT
• 27.
  실습(시연) 자바프로세스를 프로파일링 모드로띄우고 프로파일 도구로 붙어서 점검 visualvm 또는 yourkit