Kafka调优

Apache版本的Kafka

开启JMX监控

修改bin/kafka-run-class.sh（废弃）

修改处1

第一行增加(也就是开启JMX监控，制定JMX监控端口)：

JMX_PORT=9988

修改处2

某些服务器可能无法正确绑定ip，这时候我们需要显示指定绑定的host。

在参数KAFKA_JMX_OPTS，增加一个，也就是制定服务IP：

-Djava.rmi.server.hostname=192.168.10.130

正确做法开启JMX监控

修改KAFKA_HEAP_OPTS为主机运行内存的一半；

vi /software/kafka/kafka_2.12-2.2.0/bin/kafka-server-start.sh

添加export JMX_PORT="9999"，也就是添加JMX监控，用来监控Kafka集群。

if [ "x$KAFKA_HEAP_OPTS" = "x" ]; then
    export KAFKA_HEAP_OPTS="-Xmx2G -Xms2G"
    export JMX_PORT="9999"
fi

Kafka相关参数说明

JVM的优化

bin/kafka-server-start.sh

java相关系统自然离不开JVM的优化。首先想到的肯定是Heap Size的调整。

vi bin/kafka-server-start.sh

调整KAFKA_HEAP_OPTS="-Xmx16G -Xms16G”的值

推荐配置：一般HEAP SIZE的大小不超过主机内存的50%。

config/server.properties

# 当前机器在集群中的唯一标识，和zookeeper的myid性质一样  建议用自己主机的后三位  每台（主机）broker不一致
broker.id

# 当前kafka对外提供服务的端口默认是9092  生产者（producer）要以这个端口为准[kafka-0.1.x之前]
#port

# 这个参数默认是关闭的，在0.8.1有个bug，DNS解析问题，失败率的问题。  （填写本机地址即可）[kafka-0.1.x之前]
#host.name

# Kafka启动的端口[kafka-0.1.x之前]
#advertised.port=9092
# kafka的本机IP地址[kafka-0.1.x之前]
#advertised.host.name=192.168.10.130

# 监听
listeners=PLAINTEXT://192.168.10.130:9092

# 对外开放。kafka-0.1.x之后的就是这样子修改的了，启用了上面的开放端口和地址方式
advertised.listeners=PLAINTEXT://192.168.10.130:9092

# 这个是borker进行网络处理的线程数
# 【优化：num.network.threads主要处理网络io，读写缓冲区数据，基本没有io等待，配置线程数量为cpu核数加1。】
num.network.threads=3

# 这个是borker进行I/O处理的线程数
# 【优化：num.io.threads主要进行磁盘io操作，高峰期可能有些io等待，因此配置需要大些。配置线程数量为cpu核数2倍，最大不超过3倍。】
num.io.threads=8 

# 消息存放的目录，这个目录可以配置为“，”逗号分割的表达式，上面的num.io.threads要大于这个目录的个数这个目录，如果配置多个目录，新创建的topic他把消息持久化的地方是，当前以逗号分割的目录中，那个分区数最少就放那一个
log.dirs=/software/kafka/kafka-logs

# 是否允许删除topic
delete.topic.enable=true

# 发送缓冲区buffer大小，数据不是一下子就发送的，先回存储到缓冲区了到达一定的大小后在发送，能提高性能
socket.send.buffer.bytes=102400

# kafka接收缓冲区大小，当数据到达一定大小后在序列化到磁盘
socket.receive.buffer.bytes=102400

# 这个参数是向kafka请求消息或者向kafka发送消息的请请求的最大数，这个值不能超过java的堆栈大小
# 【优化：这个是int类型的取值，int类型范围是-2147483648~2147483647。不能超出，超出之后报错：org.apache.kafka.common.config.ConfigException: Invalid value 8589934592 for configuration socket.request.max.bytes: Not a number of type INT。如果很纠结的话，那就按我推荐设置为2147483600】
socket.request.max.bytes=104857600

# 默认的分区数，一个topic默认1个分区数
# 【优化：默认partition数量1，如果topic在创建时没有指定partition数量，默认使用此值。Partition的数量选取也会直接影响到Kafka集群的吞吐性能，配置过小会影响消费性能，建议改为6。】
num.partitions=1

# 默认消息的最大持久化时间，168小时，7天
log.retention.hours=168

# 消息保存的最大值5M
message.max.byte=5242880

# kafka保存消息的副本数，如果一个副本失效了，另一个还可以继续提供服务
default.replication.factor=2

# 取消息的最大直接数
replica.fetch.max.bytes=5242880

# 这个参数是：因为kafka的消息是以追加的形式落地到文件，当超过这个值的时候，kafka会新起一个文件
log.segment.bytes=1073741824

# 每隔300000毫秒去检查上面配置的log失效时间（log.retention.hours=168 ），到目录查看是否有过期的消息如果有，删除
log.retention.check.interval.ms=300000

# 是否启用log压缩，一般不用启用，启用的话可以提高性能
log.cleaner.enable=false

# 设置zookeeper的连接端口 消费的时候要以这个端口消费
zookeeper.connect=192.168.10.130:2181,192.168.10.128:2181,192.168.10.129:2181
# zookeeper连接超时时间
zookeeper.connection.timeout.ms=6000

# 【优化：为了大幅度提高producer写入吞吐量，需要定期批量写文件。一般无需改动，如果topic的数据量较小可以考虑减少log.flush.interval.ms和log.flush.interval.messages来强制刷写数据，减少可能由于缓存数据未写盘带来的不一致。推荐配置分别message 10000，间隔1s。】
# 每当producer写入10000条消息时，刷数据到磁盘
log.flush.interval.messages=10000
# 每间隔1秒钟时间，刷数据到磁盘
log.flush.interval.ms=1000

附加调优建议，涉及到Kafka消息丢失：

调优参数：

• replication.factor：这是给topic设置的参数，这个参数值必须大于1，默认是1，要求每个partition必须至少有2个副本。kafka集群虽然是高可用的，但是该topic在有broker宕机时，可能发生无法使用的情况。

  • 方法1：建立topic的时候就设置。

    bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 3 --partitions 6 --topic lzhpo01
    

    查看修改情况：

    bin/kafka-topics.sh --describe --zookeeper localhost:2181 --topic lzhpo01
    

  • 方法2：动态的给已经创建的topic添加replication-factor

    a. 首先我们配置topic的副本，保存为json文件（）
    例如， 我们想把lzhpo01的部分设置为3，（我的kafka集群有3个broker，id分别为0,1,2）， json文件名称为increase-replication-factor.json：

    {"version":1,
    "partitions":[
    {"topic":"lzhpo01","partition":0,"replicas":[0,1,2]},
    {"topic":"lzhpo01","partition":1,"replicas":[0,1,2]},
    {"topic":"lzhpo01","partition":2,"replicas":[0,1,2]}
    ]}
    

    b. 执行脚本：

    bin/kafka-reassign-partitions.sh -zookeeper 127.0.0.1:2181 --reassignment-json-file increase-replication-factor.json --execute
    

    c.查看修改之后的topic副本因子：

    bin/kafka-topics.sh --describe --zookeeper localhost:2181 --topic lzhpo01
    

    参考官方文档：https://kafka.apache.org/documentation/#basic_ops_increase_replication_factor

• min.insync.replicas：这是给Kafka服务端设置的参数，这个参数值也必须大于1，意思是要求一个Leader至少有一个Follower跟自己保持联系，也就是数据和Leader一直是保持同步的，这样子就确保了Leader挂掉了，至少还有一个Follower，不至于丢失数据。

  设置min.insync.replicas：

  bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 3 --partitions 6 --min.insync.replicas 2 --topic lzhpo01
  

• acks=all：这是在生产者端设置的，这是要求每条数据必须是写入所有的replica之后，才能认为是写入成功了。

  就举个例子，SpringBoot集成Kafka的话，可以直接在application.yml中配置：

• retries=MAX：这个是要求一旦写入失败，就无限充值，卡在这里。

  这个我没有研究过，略......

Kafka-2.2.0版本默认配置文件

# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# see kafka.server.KafkaConfig for additional details and defaults

############################# Server Basics #############################

# The id of the broker. This must be set to a unique integer for each broker.
broker.id=0

############################# Socket Server Settings #############################

# The address the socket server listens on. It will get the value returned from 
# java.net.InetAddress.getCanonicalHostName() if not configured.
#   FORMAT:
#     listeners = listener_name://host_name:port
#   EXAMPLE:
#     listeners = PLAINTEXT://your.host.name:9092
#listeners=PLAINTEXT://:9092

# Hostname and port the broker will advertise to producers and consumers. If not set, 
# it uses the value for "listeners" if configured.  Otherwise, it will use the value
# returned from java.net.InetAddress.getCanonicalHostName().
#advertised.listeners=PLAINTEXT://your.host.name:9092

# Maps listener names to security protocols, the default is for them to be the same. See the config documentation for more details
#listener.security.protocol.map=PLAINTEXT:PLAINTEXT,SSL:SSL,SASL_PLAINTEXT:SASL_PLAINTEXT,SASL_SSL:SASL_SSL

# The number of threads that the server uses for receiving requests from the network and sending responses to the network
num.network.threads=3

# The number of threads that the server uses for processing requests, which may include disk I/O
num.io.threads=8

# The send buffer (SO_SNDBUF) used by the socket server
socket.send.buffer.bytes=102400

# The receive buffer (SO_RCVBUF) used by the socket server
socket.receive.buffer.bytes=102400

# The maximum size of a request that the socket server will accept (protection against OOM)
socket.request.max.bytes=104857600


############################# Log Basics #############################

# A comma separated list of directories under which to store log files
log.dirs=/tmp/kafka-logs

# The default number of log partitions per topic. More partitions allow greater
# parallelism for consumption, but this will also result in more files across
# the brokers.
num.partitions=1

# The number of threads per data directory to be used for log recovery at startup and flushing at shutdown.
# This value is recommended to be increased for installations with data dirs located in RAID array.
num.recovery.threads.per.data.dir=1

############################# Internal Topic Settings  #############################
# The replication factor for the group metadata internal topics "__consumer_offsets" and "__transaction_state"
# For anything other than development testing, a value greater than 1 is recommended for to ensure availability such as 3.
offsets.topic.replication.factor=1
transaction.state.log.replication.factor=1
transaction.state.log.min.isr=1

############################# Log Flush Policy #############################

# Messages are immediately written to the filesystem but by default we only fsync() to sync
# the OS cache lazily. The following configurations control the flush of data to disk.
# There are a few important trade-offs here:
#    1. Durability: Unflushed data may be lost if you are not using replication.
#    2. Latency: Very large flush intervals may lead to latency spikes when the flush does occur as there will be a lot of data to flush.
#    3. Throughput: The flush is generally the most expensive operation, and a small flush interval may lead to excessive seeks.
# The settings below allow one to configure the flush policy to flush data after a period of time or
# every N messages (or both). This can be done globally and overridden on a per-topic basis.

# The number of messages to accept before forcing a flush of data to disk
#log.flush.interval.messages=10000

# The maximum amount of time a message can sit in a log before we force a flush
#log.flush.interval.ms=1000

############################# Log Retention Policy #############################

# The following configurations control the disposal of log segments. The policy can
# be set to delete segments after a period of time, or after a given size has accumulated.
# A segment will be deleted whenever *either* of these criteria are met. Deletion always happens
# from the end of the log.

# The minimum age of a log file to be eligible for deletion due to age
log.retention.hours=168

# A size-based retention policy for logs. Segments are pruned from the log unless the remaining
# segments drop below log.retention.bytes. Functions independently of log.retention.hours.
#log.retention.bytes=1073741824

# The maximum size of a log segment file. When this size is reached a new log segment will be created.
log.segment.bytes=1073741824

# The interval at which log segments are checked to see if they can be deleted according
# to the retention policies
log.retention.check.interval.ms=300000

############################# Zookeeper #############################

# Zookeeper connection string (see zookeeper docs for details).
# This is a comma separated host:port pairs, each corresponding to a zk
# server. e.g. "127.0.0.1:3000,127.0.0.1:3001,127.0.0.1:3002".
# You can also append an optional chroot string to the urls to specify the
# root directory for all kafka znodes.
zookeeper.connect=localhost:2181

# Timeout in ms for connecting to zookeeper
zookeeper.connection.timeout.ms=6000


############################# Group Coordinator Settings #############################

# The following configuration specifies the time, in milliseconds, that the GroupCoordinator will delay the initial consumer rebalance.
# The rebalance will be further delayed by the value of group.initial.rebalance.delay.ms as new members join the group, up to a maximum of max.poll.interval.ms.
# The default value for this is 3 seconds.
# We override this to 0 here as it makes for a better out-of-the-box experience for development and testing.
# However, in production environments the default value of 3 seconds is more suitable as this will help to avoid unnecessary, and potentially expensive, rebalances during application startup.
group.initial.rebalance.delay.ms=0