2022-11-05-TIL

2022-11-06-TIL

Today I Learned

Spring Data JPA Projections

QueryDSL에서만 가능한 줄 알았던 쿼리 프로젝션이 JPA에서도 가능하다는 사실을 알게 되었다. 실제로 쿼리가 해당 컬럼만 SELECT 하는지는 실제로 확인해 보아야한다.

• https://www.baeldung.com/spring-data-jpa-projections
• https://docs.spring.io/spring-data/jpa/docs/current/reference/html/

Connection이 많아지면 OOM이 발생할 수 있는가?

• https://stackoverflow.com/questions/36198102/oom-due-to-idle-db-connections-in-tomcats-connectionpool
• https://www.ibm.com/support/pages/unable-create-new-native-thread-out-memory-oom-large-amount-rmi-tcp-connections-threads-being-created

OOM killed pod

• https://discuss.istio.io/t/ingress-gateway-connection-leaks-causes-oom-killed-pod/12946

Caffeine Cache

• https://velog.io/@soongjamm/Caffeine-Cache-%EB%A5%BC-%EC%A0%81%EC%9A%A9%ED%95%B4%EB%B3%B8-%EA%B2%BD%ED%97%98
• https://blog.yevgnenll.me/posts/spring-boot-with-caffeine-cache
• https://wave1994.tistory.com/182

JVM

• https://www.holaxprogramming.com/2017/10/09/java-jvm-performance/

HikariCP

• https://www.baeldung.com/hikaricp
• https://jhparkkk.tistory.com/10

Max Connections and Mac Threads in Tomcat

• https://serverfault.com/questions/1070372/maxconnections-or-maxthreads-on-tomcat
• https://stackoverflow.com/questions/24678661/tomcat-maxthreads-vs-maxconnections
• https://serverfault.com/questions/1054410/how-to-increase-maxconnections-on-tomcat
• https://serverfault.com/questions/405893/apache-tomcat-chokes-after-300-connections
• https://bcho.tistory.com/788
• https://d2.naver.com/helloworld/1321

Key Matrics

• https://www.datadoghq.com/blog/tomcat-architecture-and-performance/
• https://lob-dev.tistory.com/entry/Monitoring-01-%ED%94%84%EB%A1%9C%EB%A9%94%ED%85%8C%EC%9A%B0%EC%8A%A4%EB%A5%BC-%EC%9D%B4%EC%9A%A9%ED%95%98%EC%97%AC-%ED%94%84%EB%A1%9C%EC%A0%9D%ED%8A%B8-%EB%A9%94%ED%8A%B8%EB%A6%AD-%EC%88%98%EC%A7%91%ED%95%98%EA%B8%B0
• https://www.ibm.com/docs/ko/cognos-analytics/11.2.0?topic=metrics-how-metric-data-is-gathered
• https://docs.aws.amazon.com/ko_kr/prometheus/latest/userguide/AMP-secure-metric-ingestion.html

Java 19 - Virtual Threads

• https://www.infoworld.com/article/3653331/jdk-19-the-new-features-in-java-19.html
• https://itnext.io/kotlin-coroutines-vs-java-virtual-threads-a-good-story-but-just-that-91038c7d21eb

Web Sockets vs Long Polling

• https://ably.com/blog/websockets-vs-long-polling

JMX

• https://www.ibm.com/docs/ko/was-zos/9.0.5?topic=scripting-using-wsadmin-java-management-extensions-jmx
• https://www.lesstif.com/java/apache-tomcat-jmx-monitoring-20776824.html
• https://narup.tistory.com/23