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Alibaba Dragonwell8 Release Notes

sanhong edited this page Mar 19, 2019 · 5 revisions

Alibaba Dragonwell 8.0-preview

openjdk version "1.8.0_202"
OpenJDK Runtime Environment (Dragonwell 8.0-preview) (build 1.8.0_202-b27)
OpenJDK 64-Bit Server VM (Dragonwell 8.0-preview) (build 25.202-b27, mixed mode)

Features

Garbage Collection

  • Use CMS (-XX:+UseConcMarkSweep) as the default GC.

Java Flight Recorder (JFR)

  • Backported from OpenJDK11 to Dragowell 8.0.
  • Added new command line option EnableJFR, which is off by default. You may specify -XX:+EnableJFR to use JFR.

Serviceability

  • Added new option mini to sub-command dump of jmap tool to skip content of primitive type arrays of heapdump. See jmap -help for more information.
  • Added new option PrintYoungGenHistoAfterParNewGC to print the object histogram of young generation after a ParNew GC. It can be opened by jinfo.
  • Added new option PrintGCRootsTraceTime to print the details of the ParNew GC like G1GC. It help users to find the problem of the long young gc pause time. It can be opened/closed by jinfo.
  • Added new option ArrayAllocationWarningSize to print the calling stack of an array allocation whose size beyond the ArrayAllocationWarningSize , the default value of this option is 512M. It can be changed by jinfo.

JWarmup

  • Added new option CompilationWarmUpRecording to enable record mode of JWarmup. JVM will dump loaded class list and hot methods into "jwarmup profile".
  • Added new option CompilationWarmUp to enable warmup compilation mode of JWarmUp. JVM will load "jwarmup profile" at startup and do warmup compilation triggered by application request.
  • Added new Java class com.alibaba.jwarmup.JWarmUp. It provides JAVA API to control JWarmUp behavior. Application can use this api to notify jvm to do warmup compilation, or check status, or ask JVM to deoptimize all warmup compiled methods.

Bug fixes

  • D13711 Fixed slow DNS reverse resolution bugs on low versions of Linux kernel.
  • Fix incorrect metaspace usage in gc log after full GC
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