kafka深度研究之路(4)-kafka和zk 配置文件详细说明（来龙去脉）之kafka配置

# The id of the broker. This must be set to a unique integer for each broker. # 必须为每个代理设置一个唯一的整数
broker.id=0

############################# Socket Server Settings ############################# # 套接字服务器设置

# 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 # 服务器用于从网络接收请求并向网络发送响应的线程数 默认是3

# The number of threads that the server uses for processing requests, which may include disk I/O
num.io.threads=8 # 服务器用于处理请求的线程数，可能包括磁盘I / O. 默认是 8

# The send buffer (SO_SNDBUF) used by the socket server ＃套接字服务器使用的发送缓冲区（SO_SNDBUF）
socket.send.buffer.bytes=102400

# The receive buffer (SO_RCVBUF) used by the socket server ＃套接字服务器使用的接收缓冲区（SO_RCVBUF）
socket.receive.buffer.bytes=102400

# The maximum size of a request that the socket server will accept (protection against OOM) # 套接字服务器将接受的请求的最大大小（防止OOM）
socket.request.max.bytes=104857600

############################# Log Basics ############################# 日志基础

# A comma separated list of directories under which to store log files ＃逗号分隔的目录列表，用于存储日志文件
log.dirs=/tmp/kafka-logs

# The default number of log partitions per topic. More partitions allow greater ＃每个主题的默认日志分区数。更多分区允许更大
# parallelism for consumption, but this will also result in more files across #dileism for consumption，但这也会导致更多的文件
# the brokers.
num.partitions=1 # 建议broker少的话，默认就几个broker 就设置成几个分区

＃在启动时用于日志恢复和在关闭时刷新的每个数据目录的线程数。
＃对于数据目录位于RAID阵列中的安装，建议增加此值。
# 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 ############################# 内部主题设置
＃组元数据内部主题“__consumer_offsets”和“__transaction_state”的复制因子
＃对于除开发测试之外的任何其他内容，建议使用大于1的值以确保可用性，例如3。
# 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
//关于这3个参数，可以在修改kafka程序中指定的 __consumer_offsets 的副本数
然后@上海-马吉辉 说只要num.partitions=3，__consumer_offsets副本数就是3，我测试不是 还是1
所以还是以offsets.topic.replication.factor参数控制为准
如果不是第一次启动kafka 那几个配置只有在初次启动生效的。 apache kafka 下载下来应该都默认是 1 吧，2.* 也是 1 啊。
可以这样修改
先停止kafka集群，删除每个broker data目录下所有__consumer_offsets_*
然后删除zookeeper下rmr /kafkatest/brokers/topics/__consumer_offsets 然后重启kafka
消费一下，这个__consumer_offsets就会创建了
注意：是在第一次消费时，才创建这个topic的，不是broker集群启动就创建，还有那个__trancation_state topic也是第一次使用事务的时候才会创建

小结：在生产上，没人去删zk里的内容，危险系数大，还是推荐动态扩副本，只要把json写对就好

############################# Log Flush Policy ############################# 日志刷新政策
＃消息立即写入文件系统，但默认情况下我们只有fsync（）才能同步
＃懒惰的操作系统缓存。以下配置控制将数据刷新到磁盘。
＃这里有一些重要的权衡：
＃1。持久性：如果您不使用复制，则可能会丢失未刷新的数据。
＃2。延迟：当刷新确实发生时，非常大的刷新间隔可能会导致延迟峰值，因为会有大量数据需要刷新。
＃3。吞吐量：冲洗通常是最昂贵的操作，并且小的冲洗间隔可能导致过多的搜索。
＃以下设置允许配置刷新策略以在一段时间后刷新数据或
＃每N条消息（或两者）。这可以在全局范围内完成，并在每个主题的基础上进行覆盖。

# 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 ＃强制刷新数据到磁盘之前要接受的消息数
#log.flush.interval.messages=10000

# The maximum amount of time a message can sit in a log before we force a flush ＃强制刷新之前消息可以在日志中停留的最长时间
#log.flush.interval.ms=1000

############################# Log Retention Policy ############################# 日志保留政策
＃以下配置控制日志段的处理。政策可以
＃设置为在一段时间后或在累积给定大小后删除段。
＃只要满足这些条件* *，就会删除一个段。删除总是发生
＃从日志的末尾开始。

# 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 ＃由于年龄原因有资格删除的日志文件的最小年龄
log.retention.hours=168

＃日志的基于大小的保留策略。除非剩下，否则将从日志中删除段
＃segments落在log.retention.bytes之下。功能独立于log.retention.hours。
＃log.retention.bytes = 1073741824
# 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

＃日志段文件的最大大小。达到此大小时，将创建新的日志段。
# The maximum size of a log segment file. When this size is reached a new log segment will be created.
log.segment.bytes=1073741824

＃检查日志段以查看是否可以删除日志段的时间间隔
# 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 # 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

# Timeout in ms for connecting to zookeeper
zookeeper.connection.timeout.ms=6000 # ZooKeeper的连接超时时间

############################# Group Coordinator Settings ############################# 组协调员设置
＃以下配置指定GroupCoordinator将延迟初始消费者重新平衡的时间（以毫秒为单位）。
＃当新成员加入组时，重新平衡将进一步延迟group.initial.rebalance.delay.ms的值，最多为max.poll.interval.ms。
＃默认值为3秒。
＃我们将此覆盖为0，因为它为开发和测试提供了更好的开箱即用体验。
＃但是，在生产环境中，默认值3秒更合适，因为这有助于避免在应用程序启动期间不必要且可能很昂贵的重新平衡。
group.initial.rebalance.delay.ms = 0