Kafka-broker配置说明

配置文件在config/server.properties

下面的一些配置可能是你需要进行修改的。

broker.id	整数，建议根据ip区分
log.dirs	kafka存放消息文件的路径，	默认/tmp/kafka-logs
port	broker用于接收producer消息的端口
zookeeper.connnect	zookeeper连接	格式为  ip1:port,ip2:port,ip3:port
message.max.bytes	单条消息的最大长度
num.network.threads	broker用于处理网络请求的线程数	如不配置默认为3，server.properties默认是2
num.io.threads	broker用于执行网络请求的IO线程数	如不配置默认为8，server.properties默认是2可适当增大，
queued.max.requests	排队等候IO线程执行的requests	默认为500
host.name	broker的hostname	默认null,建议写主机的ip,不然消费端不配置hosts会有麻烦
num.partitions	topic的默认分区数	默认1
log.retention.hours	消息被删除前保存多少小时	默认1周168小时
auto.create.topics.enable	是否可以程序自动创建Topic	默认true,建议false
default.replication.factor	消息备份数目	默认1不做复制，建议修改
num.replica.fetchers	用于复制leader消息到follower的IO线程数	默认1

下面的文档是官网给出的说明。

The essential configurations are the following:

• broker.id
• log.dirs
• zookeeper.connect

Property	Default	Description
broker.id		Each broker is uniquely identified by a non-negative integer id. This id serves as the brokers "name", and allows the broker to be moved to a different host/port without confusing consumers. You can choose any number you like so long as it is unique.
log.dirs	/tmp/kafka-logs	A comma-separated list of one or more directories in which Kafka data is stored. Each new partition that is created will be placed in the directory which currently has the fewest partitions.
port	6667	The port on which the server accepts client connections.
zookeeper.connect	null	Specifies the zookeeper connection string in the form hostname:port, where hostname and port are the host and port for a node in your zookeeper cluster. To allow connecting through other zookeeper nodes when that host is down you can also specify multiple hosts in the formhostname1:port1,hostname2:port2,hostname3:port3. Zookeeper also allows you to add a "chroot" path which will make all kafka data for this cluster appear under a particular path. This is a way to setup multiple Kafka clusters or other applications on the same zookeeper cluster. To do this give a connection string in the formhostname1:port1,hostname2:port2,hostname3:port3/chroot/pathwhich would put all this cluster's data under the path /chroot/path. Note that you must create this path yourself prior to starting the broker and consumers must use the same connection string.
message.max.bytes	1000000	The maximum size of a message that the server can receive. It is important that this property be in sync with the maximum fetch size your consumers use or else an unruly consumer will be able to publish messages too large for consumers to consume.
num.network.threads	3	The number of network threads that the server uses for handling network requests. You probably don't need to change this.
num.io.threads	8	The number of I/O threads that the server uses for executing requests. You should have at least as many threads as you have disks.
queued.max.requests	500	The number of requests that can be queued up for processing by the I/O threads before the network threads stop reading in new requests.
host.name	null	Hostname of broker. If this is set, it will only bind to this address. If this is not set, it will bind to all interfaces, and publish one to ZK.
socket.send.buffer.bytes	100 * 1024	The SO_SNDBUFF buffer the server prefers for socket connections.
socket.receive.buffer.bytes	100 * 1024	The SO_RCVBUFF buffer the server prefers for socket connections.
socket.request.max.bytes	100 * 1024 * 1024	The maximum request size the server will allow. This prevents the server from running out of memory and should be smaller than the Java heap size.
num.partitions	1	The default number of partitions per topic.
log.segment.bytes	1024 * 1024 * 1024	The log for a topic partition is stored as a directory of segment files. This setting controls the size to which a segment file will grow before a new segment is rolled over in the log.
log.segment.bytes.per.topic	""	This setting allows overriding log.segment.bytes on a per-topic basis
log.roll.hours	24 * 7	This setting will force Kafka to roll a new log segment even if the log.segment.bytes size has not been reached.
log.roll.hours.per.topic	""	This setting allows overriding log.roll.hours on a per-topic basis.
log.retention.hours	24 * 7	The number of hours to keep a log segment before it is deleted, i.e. the default data retention window for all topics. Note that if both log.retention.hours and log.retention.bytes are both set we delete a segment when either limit is exceeded.
log.retention.hours.per.topic	""	A per-topic override for log.retention.hours.
log.retention.bytes	-1	The amount of data to retain in the log for each topic-partitions. Note that this is the limit per-partition so multiple by the number of partitions to get the total data retained for the topic. Also note that if both log.retention.hours and log.retention.bytes are both set we delete a segment when either limit is exceeded.
log.retention.bytes.per.topic	""	A per-topic override for log.retention.bytes.
log.cleanup.interval.mins	10	The frequency in minutes that the log cleaner checks whether any log segment is eligible for deletion to meet the retention policies.
log.index.size.max.bytes	10 * 1024 * 1024	The maximum size in bytes we allow for the offset index for each log segment. Note that we will always pre-allocate a sparse file with this much space and shrink it down when the log rolls. If the index fills up we will roll a new log segment even if we haven't reached the log.segment.bytes limit.
log.index.interval.bytes	4096	The byte interval at which we add an entry to the offset index. When executing a fetch request the server must do a linear scan for up to this many bytes to find the correct position in the log to begin and end the fetch. So setting this value to be larger will mean larger index files (and a bit more memory usage) but less scanning. However the server will never add more than one index entry per log append (even if more than log.index.interval worth of messages are appended). In general you probably don't need to mess with this value.
log.flush.interval.messages	10000	The number of messages written to a log partition before we force an fsync on the log. Setting this higher will improve performance a lot but will increase the window of data at risk in the event of a crash (though that is usually best addressed through replication). If both this setting and log.flush.interval.ms are both used the log will be flushed when either criteria is met.
log.flush.interval.ms.per.topic	""	The per-topic override for log.flush.interval.messages, e.g., topic1:3000,topic2:6000
log.flush.scheduler.interval.ms	3000	The frequency in ms that the log flusher checks whether any log is eligible to be flushed to disk.
log.flush.interval.ms	3000	The maximum time between fsync calls on the log. If used in conjuction with log.flush.interval.messages the log will be flushed when either criteria is met.
auto.create.topics.enable	true	Enable auto creation of topic on the server. If this is set to true then attempts to produce, consume, or fetch metadata for a non-existent topic will automatically create it with the default replication factor and number of partitions.
controller.socket.timeout.ms	30000	The socket timeout for commands from the partition management controller to the replicas.
controller.message.queue.size	10	The buffer size for controller-to-broker-channels
default.replication.factor	1	The default replication factor for automatically created topics.
replica.lag.time.max.ms	10000	If a follower hasn't sent any fetch requests for this window of time, the leader will remove the follower from ISR and treat it as dead.
replica.lag.max.messages	4000	If a replica falls more than this many messages behind the leader, the leader will remove the follower from ISR and treat it as dead.
replica.socket.timeout.ms	30 * 1000	The socket timeout for network requests to the leader for replicating data.
replica.socket.receive.buffer.bytes	64 * 1024	The socket receive buffer for network requests to the leader for replicating data.
replica.fetch.max.bytes	1024 * 1024	The number of byes of messages to attempt to fetch for each partition in the fetch requests the replicas send to the leader.
replica.fetch.wait.max.ms	500	The maximum amount of time to wait time for data to arrive on the leader in the fetch requests sent by the replicas to the leader.
replica.fetch.min.bytes	1	Minimum bytes expected for each fetch response for the fetch requests from the replica to the leader. If not enough bytes, wait up to replica.fetch.wait.max.ms for this many bytes to arrive.
num.replica.fetchers	1	Number of threads used to replicate messages from leaders. Increasing this value can increase the degree of I/O parallelism in the follower broker.
replica.high.watermark.checkpoint.interval.ms	5000	The frequency with which each replica saves its high watermark to disk to handle recovery.
fetch.purgatory.purge.interval.requests	10000	The purge interval (in number of requests) of the fetch request purgatory.
producer.purgatory.purge.interval.requests	10000	The purge interval (in number of requests) of the producer request purgatory.
zookeeper.session.timeout.ms	6000	Zookeeper session timeout. If the server fails to heartbeat to zookeeper within this period of time it is considered dead. If you set this too low the server may be falsely considered dead; if you set it too high it may take too long to recognize a truly dead server.
zookeeper.connection.timeout.ms	6000	The max time that the client waits to establish a connection to zookeeper.
zookeeper.sync.time.ms	2000	How far a ZK follower can be behind a ZK leader
controlled.shutdown.enable	false	Enable controlled shutdown of the broker. If enabled, the broker will move all leaders on it to some other brokers before shutting itself down. This reduces the unavailability window during shutdown.
controlled.shutdown.max.retries	3	Number of retries to complete the controlled shutdown successfully before executing an unclean shutdown.
controlled.shutdown.retry.backoff.ms	5000	Backoff time between shutdown retries.

More details about broker configuration can be found in the scala class kafka.server.KafkaConfig.

下面看看kafka的 KafkaConfig源码。

package kafka.server

import java.util.Properties
import kafka.message.{MessageSet, Message}
import kafka.consumer.ConsumerConfig
import kafka.utils.{VerifiableProperties, ZKConfig, Utils}

/**
 * Configuration settings for the kafka server
 */
class KafkaConfig private (val props: VerifiableProperties) extends ZKConfig(props) {

  def this(originalProps: Properties) {
    this(new VerifiableProperties(originalProps))
    props.verify()
  }

  /*********** General Configuration ***********/
  
  /* the broker id for this server */
  val brokerId: Int = props.getIntInRange("broker.id", (0, Int.MaxValue))

  /* the maximum size of message that the server can receive */
  val messageMaxBytes = props.getIntInRange("message.max.bytes", 1000000 + MessageSet.LogOverhead, (0, Int.MaxValue))
  
  /* the number of network threads that the server uses for handling network requests */
  val numNetworkThreads = props.getIntInRange("num.network.threads", 3, (1, Int.MaxValue))

  /* the number of io threads that the server uses for carrying out network requests */
  val numIoThreads = props.getIntInRange("num.io.threads", 8, (1, Int.MaxValue))
  
  /* the number of queued requests allowed before blocking the network threads */
  val queuedMaxRequests = props.getIntInRange("queued.max.requests", 500, (1, Int.MaxValue))
  
  /*********** Socket Server Configuration ***********/
  
  /* the port to listen and accept connections on */
  val port: Int = props.getInt("port", 6667)

  /* hostname of broker. If this is set, it will only bind to this address. If this is not set,
   * it will bind to all interfaces, and publish one to ZK */
  val hostName: String = props.getString("host.name", null)

  /* the SO_SNDBUFF buffer of the socket sever sockets */
  val socketSendBufferBytes: Int = props.getInt("socket.send.buffer.bytes", 100*1024)
  
  /* the SO_RCVBUFF buffer of the socket sever sockets */
  val socketReceiveBufferBytes: Int = props.getInt("socket.receive.buffer.bytes", 100*1024)
  
  /* the maximum number of bytes in a socket request */
  val socketRequestMaxBytes: Int = props.getIntInRange("socket.request.max.bytes", 100*1024*1024, (1, Int.MaxValue))
  
  /*********** Log Configuration ***********/

  /* the default number of log partitions per topic */
  val numPartitions = props.getIntInRange("num.partitions", 1, (1, Int.MaxValue))
  
  /* the directories in which the log data is kept */
  val logDirs = Utils.parseCsvList(props.getString("log.dirs", props.getString("log.dir", "/tmp/kafka-logs")))
  require(logDirs.size > 0)
  
  /* the maximum size of a single log file */
  val logSegmentBytes = props.getIntInRange("log.segment.bytes", 1*1024*1024*1024, (Message.MinHeaderSize, Int.MaxValue))

  /* the maximum size of a single log file for some specific topic */
  val logSegmentBytesPerTopicMap = props.getMap("log.segment.bytes.per.topic", _.toInt > 0).mapValues(_.toInt)

  /* the maximum time before a new log segment is rolled out */
  val logRollHours = props.getIntInRange("log.roll.hours", 24*7, (1, Int.MaxValue))

  /* the number of hours before rolling out a new log segment for some specific topic */
  val logRollHoursPerTopicMap = props.getMap("log.roll.hours.per.topic", _.toInt > 0).mapValues(_.toInt)

  /* the number of hours to keep a log file before deleting it */
  val logRetentionHours = props.getIntInRange("log.retention.hours", 24*7, (1, Int.MaxValue))

  /* the number of hours to keep a log file before deleting it for some specific topic*/
  val logRetentionHoursPerTopicMap = props.getMap("log.retention.hours.per.topic", _.toInt > 0).mapValues(_.toInt)

  /* the maximum size of the log before deleting it */
  val logRetentionBytes = props.getLong("log.retention.bytes", -1)

  /* the maximum size of the log for some specific topic before deleting it */
  val logRetentionBytesPerTopicMap = props.getMap("log.retention.bytes.per.topic", _.toLong > 0).mapValues(_.toLong)

  /* the frequency in minutes that the log cleaner checks whether any log is eligible for deletion */
  val logCleanupIntervalMins = props.getIntInRange("log.cleanup.interval.mins", 10, (1, Int.MaxValue))
  
  /* the maximum size in bytes of the offset index */
  val logIndexSizeMaxBytes = props.getIntInRange("log.index.size.max.bytes", 10*1024*1024, (4, Int.MaxValue))
  
  /* the interval with which we add an entry to the offset index */
  val logIndexIntervalBytes = props.getIntInRange("log.index.interval.bytes", 4096, (0, Int.MaxValue))

  /* the number of messages accumulated on a log partition before messages are flushed to disk */
  val logFlushIntervalMessages = props.getIntInRange("log.flush.interval.messages", 10000, (1, Int.MaxValue))

  /* the maximum time in ms that a message in selected topics is kept in memory before flushed to disk, e.g., topic1:3000,topic2: 6000  */
  val logFlushIntervalMsPerTopicMap = props.getMap("log.flush.interval.ms.per.topic", _.toInt > 0).mapValues(_.toInt)

  /* the frequency in ms that the log flusher checks whether any log needs to be flushed to disk */
  val logFlushSchedulerIntervalMs = props.getInt("log.flush.scheduler.interval.ms",  3000)

  /* the maximum time in ms that a message in any topic is kept in memory before flushed to disk */
  val logFlushIntervalMs = props.getInt("log.flush.interval.ms", logFlushSchedulerIntervalMs)

  /* enable auto creation of topic on the server */
  val autoCreateTopicsEnable = props.getBoolean("auto.create.topics.enable", true)

  /*********** Replication configuration ***********/

  /* the socket timeout for controller-to-broker channels */
  val controllerSocketTimeoutMs = props.getInt("controller.socket.timeout.ms", 30000)

  /* the buffer size for controller-to-broker-channels */
  val controllerMessageQueueSize= props.getInt("controller.message.queue.size", 10)

  /* default replication factors for automatically created topics */
  val defaultReplicationFactor = props.getInt("default.replication.factor", 1)

  /* If a follower hasn't sent any fetch requests during this time, the leader will remove the follower from isr */
  val replicaLagTimeMaxMs = props.getLong("replica.lag.time.max.ms", 10000)

  /* If the lag in messages between a leader and a follower exceeds this number, the leader will remove the follower from isr */
  val replicaLagMaxMessages = props.getLong("replica.lag.max.messages", 4000)

  /* the socket timeout for network requests */
  val replicaSocketTimeoutMs = props.getInt("replica.socket.timeout.ms", ConsumerConfig.SocketTimeout)

  /* the socket receive buffer for network requests */
  val replicaSocketReceiveBufferBytes = props.getInt("replica.socket.receive.buffer.bytes", ConsumerConfig.SocketBufferSize)

  /* the number of byes of messages to attempt to fetch */
  val replicaFetchMaxBytes = props.getInt("replica.fetch.max.bytes", ConsumerConfig.FetchSize)

  /* max wait time for each fetcher request issued by follower replicas*/
  val replicaFetchWaitMaxMs = props.getInt("replica.fetch.wait.max.ms", 500)

  /* minimum bytes expected for each fetch response. If not enough bytes, wait up to replicaMaxWaitTimeMs */
  val replicaFetchMinBytes = props.getInt("replica.fetch.min.bytes", 1)

  /* number of fetcher threads used to replicate messages from a source broker.
   * Increasing this value can increase the degree of I/O parallelism in the follower broker. */
  val numReplicaFetchers = props.getInt("num.replica.fetchers", 1)
  
  /* the frequency with which the high watermark is saved out to disk */
  val replicaHighWatermarkCheckpointIntervalMs = props.getLong("replica.high.watermark.checkpoint.interval.ms", 5000L)

  /* the purge interval (in number of requests) of the fetch request purgatory */
  val fetchPurgatoryPurgeIntervalRequests = props.getInt("fetch.purgatory.purge.interval.requests", 10000)

  /* the purge interval (in number of requests) of the producer request purgatory */
  val producerPurgatoryPurgeIntervalRequests = props.getInt("producer.purgatory.purge.interval.requests", 10000)

  /*********** Controlled shutdown configuration ***********/

  /** Controlled shutdown can fail for multiple reasons. This determines the number of retries when such failure happens */
  val controlledShutdownMaxRetries = props.getInt("controlled.shutdown.max.retries", 3)

  /** Before each retry, the system needs time to recover from the state that caused the previous failure (Controller
    * fail over, replica lag etc). This config determines the amount of time to wait before retrying. */
  val controlledShutdownRetryBackoffMs = props.getInt("controlled.shutdown.retry.backoff.ms", 5000)

  /* enable controlled shutdown of the server */
  val controlledShutdownEnable = props.getBoolean("controlled.shutdown.enable", false)

}