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https://issues.apache.org/jira/browse/KAFKA-5122?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Guozhang Wang resolved KAFKA-5122.
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Resolution: Not A Problem
> Kafka Streams unexpected off-heap memory growth
> -----------------------------------------------
>
> Key: KAFKA-5122
> URL: https://issues.apache.org/jira/browse/KAFKA-5122
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Affects Versions: 0.10.2.0
> Environment: Linux 64-bit
> Oracle JVM version "1.8.0_121"
> Reporter: Jon Buffington
> Assignee: Guozhang Wang
> Priority: Minor
>
> I have a Kafka Streams application that leaks off-heap memory at a rate of
> 20MB per commit interval. The application is configured with a 1G heap; the
> heap memory does not show signs of leaking. The application reaches 16g of
> system memory usage before terminating and restarting.
> Application facts:
> * The data pipeline is source -> map -> groupByKey -> reduce -> to.
> * The reduce operation uses a tumbling time window
> TimeWindows.of(TimeUnit.HOURS.toMillis(1)).until(TimeUnit.HOURS.toMillis(168)).
> * The commit interval is five minutes (300000ms).
> * The application links to v0.10.2.0-cp1 of the Kakfa libraries. When I link
> to the current 0.10.2.1 RC3, the leak rate changes to ~10MB per commit
> interval.
> * The application uses the schema registry for two pairs of serdes. One serde
> pair is used to read from a source topic that has 40 partitions. The other
> serde pair is used by the internal changelog and repartition topics created
> by the groupByKey/reduce operations.
> * The source input rate varies between 500-1500 records/sec. The source rate
> variation does not change the size or frequency of the leak.
> * The application heap has been configured using both 1024m and 2048m. The
> only observed difference between the two JVM heap sizes is more old gen
> collections at 1024m although there is little difference in throughput. JVM
> settings are {-server -Djava.awt.headless=true -Xss256k
> -XX:MaxMetaspaceSize=128m -XX:ReservedCodeCacheSize=64m
> -XX:CompressedClassSpaceSize=32m -XX:MaxDirectMemorySize=128m
> -XX:+AlwaysPreTouch -XX:+UseG1GC -XX:MaxGCPauseMillis=50
> -XX:InitiatingHeapOccupancyPercent=35 -XX:+PerfDisableSharedMem
> -XX:+UseStringDeduplication -XX:MinMetaspaceFreeRatio=50
> -XX:MaxMetaspaceFreeRatio=80}
> * We configure a custom RocksDBConfigSetter to set
> options.setMaxBackgroundCompactions(Runtime.getRuntime.availableProcessors)
> * Per
> <http://mail-archives.apache.org/mod_mbox/kafka-users/201702.mbox/%3ccahwhrrxxpwgyvr1ctwgoudkr7cqkaq+52phfpuzs4j-wv7k...@mail.gmail.com%3e>,
> the SSTables are being compacted. Total disk usage for the state files
> (RocksDB) is ~2.5g. Per partition and window, there are 3-4 SSTables.
> * The application is written in Scala and compiled using version 2.12.1.
> • Oracle JVM version "1.8.0_121"
> Various experiments that had no effect on the leak rate:
> * Tried different RocksDB block sizes (4k, 16k, and 32k).
> * Different numbers of instances (1, 2, and 4).
> * Different numbers of threads (1, 4, 10, 40).
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