Hi Ben, Well, I had a similar question and Jon Haddad was preferring ParNew + CMS over G1GC for java 8. https://lists.apache.org/thread.html/283547619b1dcdcddb80947a45e2178158394e317f3092b8959ba879@%3Cuser.cassandra.apache.org%3E It depends on your JVM and in any case, I would test it based on your workload.
What's your experience of running Cassandra in k8s. Are you using the Cassandra Kubernetes Operator? How do you monitor it and how do you perform disaster recovery backup? Best, Sergio Il giorno ven 1 nov 2019 alle ore 14:14 Ben Mills <b...@bitbrew.com> ha scritto: > Thanks Sergio - that's good advice and we have this built into the plan. > Have you heard a solid/consistent recommendation/requirement as to the > amount of memory heap requires for G1GC? > > On Fri, Nov 1, 2019 at 5:11 PM Sergio <lapostadiser...@gmail.com> wrote: > >> In any case I would test with tlp-stress or Cassandra stress tool any >> configuration >> >> Sergio >> >> On Fri, Nov 1, 2019, 12:31 PM Ben Mills <b...@bitbrew.com> wrote: >> >>> Greetings, >>> >>> We are planning a Cassandra upgrade from 3.7 to 3.11.5 and considering a >>> change to the GC config. >>> >>> What is the minimum amount of memory that needs to be allocated to heap >>> space when using G1GC? >>> >>> For GC, we currently use CMS. Along with the version upgrade, we'll be >>> running the stateful set of Cassandra pods on new machine types in a new >>> node pool with 12Gi memory per node. Not a lot of memory but an >>> improvement. We may be able to go up to 16Gi memory per node. We'd like to >>> continue using these heap settings: >>> >>> -XX:+UnlockExperimentalVMOptions >>> -XX:+UseCGroupMemoryLimitForHeap >>> -XX:MaxRAMFraction=2 >>> >>> which (if 12Gi per node) would provide 6Gi memory for heap (i.e. half of >>> total available). >>> >>> Here are some details on the environment and configs in the event that >>> something is relevant. >>> >>> Environment: Kubernetes >>> Environment Config: Stateful set of 3 replicas >>> Storage: Persistent Volumes >>> Storage Class: SSD >>> Node OS: Container-Optimized OS >>> Container OS: Ubuntu 16.04.3 LTS >>> Data Centers: 1 >>> Racks: 3 (one per zone) >>> Nodes: 3 >>> Tokens: 4 >>> Replication Factor: 3 >>> Replication Strategy: NetworkTopologyStrategy (all keyspaces) >>> Compaction Strategy: STCS (all tables) >>> Read/Write Requirements: Blend of both >>> Data Load: <1GB per node >>> gc_grace_seconds: default (10 days - all tables) >>> >>> GC Settings: (CMS) >>> >>> -XX:+UseParNewGC >>> -XX:+UseConcMarkSweepGC >>> -XX:+CMSParallelRemarkEnabled >>> -XX:SurvivorRatio=8 >>> -XX:MaxTenuringThreshold=1 >>> -XX:CMSInitiatingOccupancyFraction=75 >>> -XX:+UseCMSInitiatingOccupancyOnly >>> -XX:CMSWaitDuration=30000 >>> -XX:+CMSParallelInitialMarkEnabled >>> -XX:+CMSEdenChunksRecordAlways >>> >>> Any ideas are much appreciated. >>> >>
