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https://issues.apache.org/jira/browse/KAFKA-7304?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16631998#comment-16631998
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Rajini Sivaram commented on KAFKA-7304:
---------------------------------------
[~yuyang08] We came across a similar issue with large number of clients for
which we had a heap dump. There was no leak in `Selector#closingChannels` which
were mostly empty, but there were a large number of channels in
`Selector#channels`, mainly due to client reconnections. I have submitted two
PRs to reduce memory pressure in this type of scenario:
* [https://github.com/apache/kafka/pull/5713]
* [https://github.com/apache/kafka/pull/5712]
It will be good to know if these help with your scenario. We are also
considering limiting the number of new connections processed in each iteration
by the broker to improve fairness between processing of new and existing
connections, but we need to do more testing for that before submitting a PR.
> 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, Screen Shot 2018-08-28 at
> 11.09.45 AM.png, Screen Shot 2018-08-29 at 10.49.03 AM.png, Screen Shot
> 2018-08-29 at 10.50.47 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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