基于kafka_2.12-2.2.0

# 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的ID，每个broker必须又有唯一的值。
broker.id=1

############################# 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
#Socket服务器监听的地址，如果没有设置，则监听java.net.InetAddress.getCanonicalHostName()返回的地址
listeners=PLAINTEXT://172.16.3.177:9092

# 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().
#broker通知到producers和consumers的主机地址和端口号。如果未设置，使用listeners的配置。
#否则，使用java.net.InetAddress#.getCanonicalHostName()返回的值。
#如果均为设置，拿到的值为localhot:9092,将造成无法连接其他机器
#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名称到安全协议。默认所有的listener使用相同的安全协议。PLAINTEXT为明码文本协议
#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
#服务器用来从网络接收请求和发送响应数据到网络的线程数
num.network.threads=3

# The number of threads that the server uses for processing requests, which may include disk I/O
#服务器用来处理请求的线程数，可能包含磁盘I/O的线程。
num.io.threads=8

# The send buffer (SO_SNDBUF) used by the socket server
#服务器发送数据的缓存大小。
socket.send.buffer.bytes=102400

# The receive buffer (SO_RCVBUF) used by the socket server
#服务器接收数据的缓存大小。
socket.receive.buffer.bytes=102400

# The maximum size of a request that the socket server will accept (protection against OOM)
#socket服务器接收的单个request大小的最大值。
socket.request.max.bytes=104857600

#Kafka的数据都是存储在log文件中的，log的配置即是data的配置

############################# Log Basics #############################
#Log 基本设置：
# A comma separated list of directories under which to store log files
#Kafka存储log文件的目录，多个目录用逗号分隔。
log.dirs=/home/logs/kafka

# 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.
#topic的默认分割的分区个数。多分区允许消费者并行获取数据，但这也会造成brokers交叉保存多个文件。
num.partitions=10

# 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.
#当Kafka启动时恢复数据和关闭时保存数据到磁盘时使用的线程个数。
num.recovery.threads.per.data.dir=2

############################# 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.
#副本个数。除了开发测试外，其他情况都建议将该值设置为大于1的值以保证高可用，比如：3。
offsets.topic.replication.factor=2
transaction.state.log.replication.factor=2
transaction.state.log.min.isr=2

############################# Log Flush Policy #############################
#Log持久化策略：
#Message会立即写入到文件系统。但我们只使用了fsync()方法，该操作并不会立即执行OS的写入磁盘操作。
#下面几个参数可以配置写入磁盘的策略。

# 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
#在持久化到磁盘前message最大接收条数。
#log.flush.interval.messages=10000

# The maximum amount of time a message can sit in a log before we force a flush
#持久化的最大时间间隔。
#log.flush.interval.ms=1000

############################# Log Retention Policy #############################
#Log保留策略：
#下面的参数配置如何处理log分片。可以配置为删除超过指定时间的数据，或超过指定大小的数据。
#如果一个segment符合其中任意调节，就会被删除。

# 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
#将已保存超过7天的数据删除。
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.
#基于数据大小的log保存策略。当分片的大小超过该值时，就会被删除。改功能不依赖于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.
#单个分片的上限，达到该大小后会生成新的日志分片。
log.segment.bytes=1073741824

# The interval at which log segments are checked to see if they can be deleted according
# to the retention policies
#日志分片的检测时间间隔，每隔该事件会根据log保留策略决定是否删除log分片。
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连接字符串。是一个使用逗号分隔的host：port字符串。
zookeeper.connect=172.16.3.177:12181,172.16.3.178:12181,172.16.3.179:12181

# Timeout in ms for connecting to zookeeper
#连接zookeeper的超时时间。
zookeeper.connection.timeout.ms=6000


############################# Group Coordinator Settings #############################
#消费者分组协调者设置：

# 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.
#在开发测试环境下该值设置为0，保证启动后马上可以使用。但在生产环境下，默认值3秒更适合。
group.initial.rebalance.delay.ms=0