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2019-10-16

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#jvm
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2019-10-16
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frankitox16:10:45

Hello! I was looking at the logs of a web server when I found: 

OpenJDK 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release
After looking at the set of JVM options we use when running java (openjdk 8) I found: 
-server
-Xms5G
-Xmx5G
-XX:+DoEscapeAnalysis
-XX:+UseParNewGC
-XX:+UseConcMarkSweepGC
-XX:+CMSConcurrentMTEnabled
-XX:+CMSIncrementalMode
-XX:MaxNewSize=257m
-XX:NewSize=256m
-XX:+UseTLAB
-XX:MaxTenuringThreshold=0
I'm not going to update java right now, but I'd like to know if it is safe to remove this +CMSIncrementalMode flag? And if it is actually doing something?

frankitox23:10:05

From a couple of articles it seems java is dropping support for the Concurrent Mark Sweep Garbage Collector, they will focus on G1. Since latest Clojure still supports java 8 I'm not tweaking those settings yet. - Why CMS Garbage Collector deprecating: https://www.linkedin.com/pulse/jvm-why-cms-garbage-collector-deprecating-kunal-saxena/ - Info about different garbage collectors: https://www.baeldung.com/jvm-garbage-collectors