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https://issues.apache.org/jira/browse/KAFKA-7304?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16592762#comment-16592762
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Yu Yang commented on KAFKA-7304:
--------------------------------
Thanks for looking into this, [~yuzhih...@gmail.com]! We also did more
experiments on our side with various settings. Based on the initial experiment,
it seems to me that your patch earlier has fixed the resource leakage in the
closing channel. Meanwhile with >40k concurrent ssl connections, sometimes the
brokers may still run into OOM issue as the connections are not closed on time.
Currently I am experimenting with increased heap size. Will report back to the
thread if we have any findings.
> memory leakage in org.apache.kafka.common.network.Selector
> ----------------------------------------------------------
>
> Key: KAFKA-7304
> URL: https://issues.apache.org/jira/browse/KAFKA-7304
> Project: Kafka
> Issue Type: Bug
> Components: core
> Affects Versions: 1.1.0, 1.1.1
> Reporter: Yu Yang
> Priority: Critical
> Fix For: 1.1.2, 2.0.1, 2.1.0
>
> Attachments: 7304.v4.txt, 7304.v7.txt, Screen Shot 2018-08-16 at
> 11.04.16 PM.png, Screen Shot 2018-08-16 at 11.06.38 PM.png, Screen Shot
> 2018-08-16 at 12.41.26 PM.png, Screen Shot 2018-08-16 at 4.26.19 PM.png,
> Screen Shot 2018-08-17 at 1.03.35 AM.png, Screen Shot 2018-08-17 at 1.04.32
> AM.png, Screen Shot 2018-08-17 at 1.05.30 AM.png
>
>
> We are testing secured writing to kafka through ssl. Testing at small scale,
> ssl writing to kafka was fine. However, when we enabled ssl writing at a
> larger scale (>40k clients write concurrently), the kafka brokers soon hit
> OutOfMemory issue with 4G memory setting. We have tried with increasing the
> heap size to 10Gb, but encountered the same issue.
> We took a few heap dumps , and found that most of the heap memory is
> referenced through org.apache.kafka.common.network.Selector objects. There
> are two Channel maps field in Selector. It seems that somehow the objects is
> not deleted from the map in a timely manner.
> One observation is that the memory leak seems relate to kafka partition
> leader changes. If there is broker restart etc. in the cluster that caused
> partition leadership change, the brokers may hit the OOM issue faster.
> {code}
> private final Map<String, KafkaChannel> channels;
> private final Map<String, KafkaChannel> closingChannels;
> {code}
> Please see the attached images and the following link for sample gc
> analysis.
> http://gceasy.io/my-gc-report.jsp?p=c2hhcmVkLzIwMTgvMDgvMTcvLS1nYy5sb2cuMC5jdXJyZW50Lmd6LS0yLTM5LTM0
> the command line for running kafka:
> {code}
> java -Xms10g -Xmx10g -XX:NewSize=512m -XX:MaxNewSize=512m
> -Xbootclasspath/p:/usr/local/libs/bcp -XX:MetaspaceSize=128m -XX:+UseG1GC
> -XX:MaxGCPauseMillis=25 -XX:InitiatingHeapOccupancyPercent=35
> -XX:G1HeapRegionSize=16M -XX:MinMetaspaceFreeRatio=25
> -XX:MaxMetaspaceFreeRatio=75 -XX:+PrintGCDetails -XX:+PrintGCDateStamps
> -XX:+PrintTenuringDistribution -Xloggc:/var/log/kafka/gc.log
> -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=40 -XX:GCLogFileSize=50M
> -Djava.awt.headless=true
> -Dlog4j.configuration=file:/etc/kafka/log4j.properties
> -Dcom.sun.management.jmxremote
> -Dcom.sun.management.jmxremote.authenticate=false
> -Dcom.sun.management.jmxremote.ssl=false
> -Dcom.sun.management.jmxremote.port=9999
> -Dcom.sun.management.jmxremote.rmi.port=9999 -cp /usr/local/libs/*
> kafka.Kafka /etc/kafka/server.properties
> {code}
> We use java 1.8.0_102, and has applied a TLS patch on reducing
> X509Factory.certCache map size from 750 to 20.
> {code}
> java -version
> java version "1.8.0_102"
> Java(TM) SE Runtime Environment (build 1.8.0_102-b14)
> Java HotSpot(TM) 64-Bit Server VM (build 25.102-b14, mixed mode)
> {code}
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