工作中经常使用到kafka作为消息中间件，针对server.properties配置文件参数说明如下：
server.properties中所有配置参数说明如下列表：
| 参数 | 说明(解释) |
| broker.id =0 | 每一个broker在集群中的唯一表示，要求是正数。当该服务器的IP地址发生改变时，broker.id没有变化，则不会影响consumers的消息情况 |
| log.dirs=/data/kafka-logs | kafka数据的存放地址，多个地址的话用逗号分割,多个目录分布在不同磁盘上可以提高读写性能 /data/kafka-logs-1，/data/kafka-logs-2 |
| port =9092 | broker server服务端口 |
| message.max.bytes =6525000 | 表示消息体的最大大小，单位是字节 |
| num.network.threads =4 | broker处理消息的最大线程数，一般情况下数量为cpu核数 |
| num.io.threads =8 | broker处理磁盘IO的线程数，数值为cpu核数2倍 |
| background.threads =4 | 一些后台任务处理的线程数，例如过期消息文件的删除等，一般情况下不需要去做修改 |
| queued.max.requests =500 | 等待IO线程处理的请求队列最大数，若是等待IO的请求超过这个数值，那么会停止接受外部消息，应该是一种自我保护机制 |
| host.name | broker的主机地址，若是设置了，那么会绑定到这个地址上，若是没有，会绑定到所有的接口上，并将其中之一发送到ZK，一般不设置 |
| socket.send.buffer.bytes=100*1024 | socket的发送缓冲区，socket的调优参数SO_SNDBUFF |
| socket.receive.buffer.bytes =100*1024 | socket的接受缓冲区，socket的调优参数SO_RCVBUFF |
| socket.request.max.bytes =100*1024*1024 | socket请求的最大数值，防止serverOOM，message.max.bytes必然要小于socket.request.max.bytes，会被topic创建时的指定参数覆盖 |
| log.segment.bytes =1024*1024*1024 | topic的分区是以一堆segment文件存储的，这个控制每个segment的大小，会被topic创建时的指定参数覆盖 |
| log.roll.hours =24*7 | 这个参数会在日志segment没有达到log.segment.bytes设置的大小，也会强制新建一个segment会被 topic创建时的指定参数覆盖 |
| log.cleanup.policy = delete | 日志清理策略选择有：delete和compact主要针对过期数据的处理，或是日志文件达到限制的额度，会被 topic创建时的指定参数覆盖 |
| log.retention.minutes=300 或 log.retention.hours=168 |
数据文件保留多长时间， 存储的最大时间超过这个时间会根据log.cleanup.policy设置数据清除策略 log.retention.bytes和log.retention.minutes或log.retention.hours任意一个达到要求，都会执行删除 有2删除数据文件方式： 按照文件大小删除：log.retention.bytes 按照2种不同时间粒度删除：分别为分钟，小时 |
| log.retention.bytes=-1 | topic每个分区的最大文件大小，一个topic的大小限制 = 分区数*log.retention.bytes。-1没有大小限log.retention.bytes和log.retention.minutes任意一个达到要求，都会执行删除，会被topic创建时的指定参数覆盖 |
| log.retention.check.interval.ms=5minutes | 文件大小检查的周期时间，是否处罚 log.cleanup.policy中设置的策略 |
| log.cleaner.enable=false | 是否开启日志清理 |
| log.cleaner.threads = 2 | 日志清理运行的线程数 |
| log.cleaner.io.max.bytes.per.second=None | 日志清理时候处理的最大大小 |
| log.cleaner.dedupe.buffer.size=500*1024*1024 | 日志清理去重时候的缓存空间，在空间允许的情况下，越大越好 |
| log.cleaner.io.buffer.size=512*1024 | 日志清理时候用到的IO块大小一般不需要修改 |
| log.cleaner.io.buffer.load.factor =0.9 | 日志清理中hash表的扩大因子一般不需要修改 |
| log.cleaner.backoff.ms =15000 | 检查是否处罚日志清理的间隔 |
| log.cleaner.min.cleanable.ratio=0.5 | 日志清理的频率控制，越大意味着更高效的清理，同时会存在一些空间上的浪费，会被topic创建时的指定参数覆盖 |
| log.cleaner.delete.retention.ms =1day | 对于压缩的日志保留的最长时间，也是客户端消费消息的最长时间，同log.retention.minutes的区别在于一个控制未压缩数据，一个控制压缩后的数据。会被topic创建时的指定参数覆盖 |
| log.index.size.max.bytes =10*1024*1024 | 对于segment日志的索引文件大小限制，会被topic创建时的指定参数覆盖 |
| log.index.interval.bytes =4096 | 当执行一个fetch操作后，需要一定的空间来扫描最近的offset大小，设置越大，代表扫描速度越快，但是也更好内存，一般情况下不需要搭理这个参数 |
| log.flush.interval.messages=None 例如log.flush.interval.messages=1000 表示每当消息记录数达到1000时flush一次数据到磁盘 |
log文件”sync”到磁盘之前累积的消息条数,因为磁盘IO操作是一个慢操作,但又是一个”数据可靠性"的必要手段,所以此参数的设置,需要在"数据可靠性"与"性能"之间做必要的权衡.如果此值过大,将会导致每次"fsync"的时间较长(IO阻塞),如果此值过小,将会导致"fsync"的次数较多,这也意味着整体的client请求有一定的延迟.物理server故障,将会导致没有fsync的消息丢失 |
| log.flush.scheduler.interval.ms =3000 | 检查是否需要固化到硬盘的时间间隔 |
| log.flush.interval.ms = None 例如：log.flush.interval.ms=1000 表示每间隔1000毫秒flush一次数据到磁盘 |
仅仅通过interval来控制消息的磁盘写入时机,是不足的.此参数用于控制"fsync"的时间间隔,如果消息量始终没有达到阀值,但是离上一次磁盘同步的时间间隔达到阀值,也将触发. |
| log.delete.delay.ms =60000 | 文件在索引中清除后保留的时间一般不需要去修改 |
| log.flush.offset.checkpoint.interval.ms =60000 | 控制上次固化硬盘的时间点，以便于数据恢复一般不需要去修改 |
| auto.create.topics.enable =true | 是否允许自动创建topic，若是false，就需要通过命令创建topic |
| default.replication.factor =1 | 是否允许自动创建topic，若是false，就需要通过命令创建topic |
| num.partitions =1 | 每个topic的分区个数，若是在topic创建时候没有指定的话会被topic创建时的指定参数覆盖 |
| 以下是kafka中Leader,replicas配置参数 | |
| controller.socket.timeout.ms =30000 | partition leader与replicas之间通讯时,socket的超时时间 |
| controller.message.queue.size=10 | partition leader与replicas数据同步时,消息的队列尺寸 |
| replica.lag.time.max.ms =10000 | replicas响应partition leader的最长等待时间，若是超过这个时间，就将replicas列入ISR(in-sync replicas)，并认为它是死的，不会再加入管理中 |
| replica.lag.max.messages =4000 | 如果follower落后与leader太多,将会认为此follower[或者说partition relicas]已经失效 ##通常,在follower与leader通讯时,因为网络延迟或者链接断开,总会导致replicas中消息同步滞后 ##如果消息之后太多,leader将认为此follower网络延迟较大或者消息吞吐能力有限,将会把此replicas迁移 ##到其他follower中. ##在broker数量较少,或者网络不足的环境中,建议提高此值 |
| replica.socket.timeout.ms=30*1000 | follower与leader之间的socket超时时间 |
| replica.socket.receive.buffer.bytes=64*1024 | leader复制时候的socket缓存大小 |
| replica.fetch.max.bytes =1024*1024 | replicas每次获取数据的最大大小 |
| replica.fetch.wait.max.ms =500 | replicas同leader之间通信的最大等待时间，失败了会重试 |
| replica.fetch.min.bytes =1 | fetch的最小数据尺寸,如果leader中尚未同步的数据不足此值,将会阻塞,直到满足条件 |
| num.replica.fetchers=1 | leader进行复制的线程数，增大这个数值会增加follower的IO |
| replica.high.watermark.checkpoint.interval.ms =5000 | 每个replica检查是否将最高水位进行固化的频率 |
| controlled.shutdown.enable =false | 是否允许控制器关闭broker ,若是设置为true,会关闭所有在这个broker上的leader，并转移到其他broker |
| controlled.shutdown.max.retries =3 | 控制器关闭的尝试次数 |
| controlled.shutdown.retry.backoff.ms =5000 | 每次关闭尝试的时间间隔 |
| leader.imbalance.per.broker.percentage =10 | leader的不平衡比例，若是超过这个数值，会对分区进行重新的平衡 |
| leader.imbalance.check.interval.seconds =300 | 检查leader是否不平衡的时间间隔 |
| offset.metadata.max.bytes | 客户端保留offset信息的最大空间大小 |
| kafka中zookeeper参数配置 | |
| zookeeper.connect = localhost:2181 | zookeeper集群的地址，可以是多个，多个之间用逗号分割 hostname1:port1,hostname2:port2,hostname3:port3 |
| zookeeper.session.timeout.ms=6000 | ZooKeeper的最大超时时间，就是心跳的间隔，若是没有反映，那么认为已经死了，不易过大 |
| zookeeper.connection.timeout.ms =6000 | ZooKeeper的连接超时时间 |
| zookeeper.sync.time.ms =2000 | ZooKeeper集群中leader和follower之间的同步实际那 |
server.properties配置文件样例
# 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
# Switch to enable topic deletion or not, default value is false
#delete.topic.enable=true
############################# 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 handling network requests
num.network.threads=3
# The number of threads doing 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 seperated list of directories under which to store log files
#log.dirs=/tmp/kafka-logs
log.dirs=./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
############################# 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 exceessive 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 as long as the remaining
# segments don't 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
listeners=PLAINTEXT://127.0.0.1:9092
advertised.listeners=PLAINTEXT://127.0.0.1:9092
