############################# 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:

#    . Durability: Unflushed data may be lost if you are not using replication.

#    . 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.

#    . 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

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.

#log.retention.bytes=

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

log.segment.bytes=

# 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=

# By default the log cleaner is disabled and the log retention policy will default to just delete segments after their retention expires.

# If log.cleaner.enable=true is set the cleaner will be enabled and individual logs can then be marked for log compaction.

log.cleaner.enable=false

（这是Kafka用来实现一个Topic消息的广播（发给所有的Consumer）和单播（发给某一个Consumer）的手段。

一个Topic可以对应多个Consumer Group。如果需要实现广播，只要每个Consumer有一个独立的Group就可以了。

要实现单播只要所有的Consumer在同一个Group里。用Consumer Group还可以将Consumer进行*的分组而不需要多次发送消息到不同的Topic。）

# 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 #############################

##################################################################################

#  broker就是一个kafka的部署实例，在一个kafka集群中，每一台kafka都要有一个broker.id

#  并且，该id唯一，且必须为整数

##################################################################################

broker.id=

############################# 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 = security_protocol://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

##################################################################################

#The number of threads handling network requests

# 默认处理网络请求的线程个数 3个

##################################################################################

num.network.threads=

##################################################################################

# The number of threads doing disk I/O

# 执行磁盘IO操作的默认线程个数

##################################################################################

num.io.threads=

##################################################################################

# The send buffer (SO_SNDBUF) used by the socket server

# socket服务使用的进行发送数据的缓冲区大小，默认100kb

##################################################################################

socket.send.buffer.bytes=

##################################################################################

# The receive buffer (SO_SNDBUF) used by the socket server

# socket服务使用的进行接受数据的缓冲区大小，默认100kb

##################################################################################

socket.receive.buffer.bytes=

##################################################################################

# The maximum size of a request that the socket server will accept (protection against OOM)

# socket服务所能够接受的最大的请求量，防止出现OOM(Out of memory)内存溢出，默认值为：100m

# （应该是socker server所能接受的一个请求的最大大小，默认为100M）

##################################################################################

socket.request.max.bytes=

############################# Log Basics （数据相关部分，kafka的数据称为log）#############################

##################################################################################

# A comma seperated list of directories under which to store log files

# 一个用逗号分隔的目录列表，用于存储kafka接受到的数据

##################################################################################

log.dirs=/home/uplooking/data/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.

# 每一个topic所对应的log的partition分区数目，默认1个。更多的partition数目会提高消费

# 并行度，但是也会导致在kafka集群中有更多的文件进行传输

# （partition就是分布式存储，相当于是把一份数据分开几份来进行存储，即划分块、划分分区的意思）

##################################################################################

num.partitions=

##################################################################################

# 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.

# 每一个数据目录用于在启动kafka时恢复数据和在关闭时刷新数据的线程个数。如果kafka数据存储在磁盘阵列中

# 建议此值可以调整更大。

##################################################################################

num.recovery.threads.per.data.dir=

############################# Log Flush Policy （数据刷新策略）#############################

# 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（平衡） here:

#    . Durability 持久性: Unflushed data may be lost if you are not using replication.

#    . Latency 延时性: Very large flush intervals may lead to latency spikes when the flush does occur as there will be a lot of data to flush.

#    . Throughput 吞吐量: 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.

# kafka中只有基于消息条数和时间间隔数来制定数据刷新策略，而没有大小的选项，这两个选项可以选择配置一个

# 当然也可以两个都配置，默认情况下两个都配置，配置如下。

# The number of messages to accept before forcing a flush of data to disk

# 消息刷新到磁盘中的消息条数阈值

#log.flush.interval.messages=

# The maximum amount of time a message can sit in a log before we force a flush

# 消息刷新到磁盘生成一个log数据文件的时间间隔

#log.flush.interval.ms=

############################# Log Retention Policy（数据保留策略） #############################

# The following configurations control the disposal（清理） of log segments（分片）. The policy can

# be set to delete segments after a period of time, or after a given size has accumulated（累积）.

# A segment will be deleted whenever（无论什么时间） *either* of these criteria（标准） are met. Deletion always happens

# from the end of the log.

# 下面的配置用于控制数据片段的清理，只要满足其中一个策略（基于时间或基于大小），分片就会被删除

# The minimum age of a log file to be eligible for deletion

# 基于时间的策略，删除日志数据的时间，默认保存7天

log.retention.hours=

# 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. 1G

# 基于大小的策略，1G

#log.retention.bytes=

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

# 数据分片策略

log.segment.bytes=

# The interval at which log segments are checked to see if they can be deleted according

# to the retention policies 5分钟

# 每隔多长时间检测数据是否达到删除条件

log.retention.check.interval.ms=

############################# 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=uplooking01:,uplooking02:,uplooking03:

# Timeout in ms for connecting to zookeeper

zookeeper.connection.timeout.ms=