【问题标题】:Kafka topics with different retention although having the same configuration尽管具有相同的配置,但具有不同保留的 Kafka 主题
【发布时间】:2020-11-16 16:54:10
【问题描述】:

我有一个关于保留主题消息的问题。

我有以下情况:

  • 两个 Kafka 主题;
  • 经纪人有属性log.retention.hours=1;

分别描述两个主题的命令:

[oracleas@zkafka01vdc bin]$ ./kafka-topics.sh --zookeeper 192.168.163.71:2181 --describe --topic digital-lending
Topic:digital-lending   PartitionCount:3        ReplicationFactor:2     Configs:
        Topic: digital-lending  Partition: 0    Leader: 3       Replicas: 1,3   Isr: 3,1
        Topic: digital-lending  Partition: 1    Leader: 2       Replicas: 2,1   Isr: 1,2
        Topic: digital-lending  Partition: 2    Leader: 3       Replicas: 3,2   Isr: 3,2

[oracleas@zkafka01vdc bin]$ ./kafka-topics.sh --zookeeper 192.168.163.71:2181 --describe --topic digital-onboarding
Topic:digital-onboarding        PartitionCount:1        ReplicationFactor:1     Configs:
        Topic: digital-onboarding       Partition: 0    Leader: 1       Replicas: 1     Isr: 1

问题是:

  1. 主题数字入职如何保留 1 天和数字借贷 1 周(根据我的观察 - 尝试了几次从队列中获取所有消息,一个主题的保留时间为 1 天,另一个主题一个是 1 周)?

  2. 除了--describe 命令和server.properties 文件,还有其他地方设置吗?

编辑 1:

server.properties 文件:

# 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=1

# 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://10.206.23.71:9092
listeners=EXTERNAL://zkafka01vdc-pub:9092,INTERNAL://zkafka01vdc-int:9093

# 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://zkafka01vdc.bcr.wan:9092
advertised.listeners=EXTERNAL://zkafka01vdc.bcr.wan:9092,INTERNAL://zkafka01vdc-int:9093

# 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
listener.security.protocol.map=EXTERNAL:PLAINTEXT,INTERNAL:PLAINTEXT

inter.broker.listener.name=INTERNAL

# The number of threads that the server uses for receiving requests from the network and sending responses to the network
num.network.threads=3

# The number of threads that the server uses for processing requests, which may include 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=/zkafka/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.
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

############################# 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.
offsets.topic.replication.factor=1
transaction.state.log.replication.factor=1
transaction.state.log.min.isr=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=1

# 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=30000

############################# 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=zkafka01vdc-int:2181,zkafka02vdc-int:2181,zkafka03vdc-int:2181

# Timeout in ms for connecting to zookeeper
zookeeper.connection.timeout.ms=6000


############################# Group Coordinator Settings #############################

# 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.
group.initial.rebalance.delay.ms=0

【问题讨论】:

    标签: apache-kafka kafka-topic


    【解决方案1】:

    请记住,保留时间不是硬性上限,而是您的消息留在主题中的下限。请务必注意,来自 active 段的消息永远不会从主题中删除,即使消息超过了保留时间。更多详情请见data still remains in kafka topic even after retention time

    在 Kafka 中,您可以通过集群范围的设置或特定主题的设置来设置保留时间。如果您在创建主题时未指定主题特定值,则集群范围的设置将作为默认设置。

    在主题配置的 Kafka 文档中是这样写的:

    retention.ms:如果我们使用“删除”保留策略,此配置控制在丢弃旧日志段以释放空间之前保留日志的最长时间。这代表了消费者必须在多长时间内读取其数据的 SLA。如果设置为 -1,则不应用时间限制。

    Type:                       long
    Default:                    604800000
    Valid Values:               [-1,...]
    Server Default Property:    log.retention.ms
    Importance:                 medium
    

    如果您不设置,将使用log.retention.ms(或log.retention.hours)。

    【讨论】:

    • 感谢您的回答。但是我刚才写的保留怎么可能呢?在 1 小时的属性文件中具有该值并且没有覆盖该主题的保留?从你的回答我无法弄清楚。在属性文件中我没有retention.ms
    • 那你怎么知道保留时间正好是 1 周 1 天?
    • 在客户端,我正在更改 cliend-id 和 group-id 以便从头开始再次拖动所有文件。我在不同的日子做了这个,它是一样的。一个是我最近 7 天看到的,一个是 1 天左右的(我说的是周围,因为它似乎只从早上看到文件)
    • 在这种情况下,我想我们在这里讨论的是您主题中的清理策略和活动/非活动段。
    • 作为建议,请尝试重新表述您问题中的部分“保留 1 天和数字化 1 周?”反映你的观察。正如您在 cmets 中解释的那样,这似乎不是一个困难的设置,而是基于您的观察的假设。到目前为止给出的两个答案都假设保留时间为 1 天和 1 周是一个既定事实。
    【解决方案2】:

    您可以运行以下命令来设置每个主题的保留配置:

    bin/kafka-configs.sh \
        --zookeeper 192.168.163.71:2181 \
        --alter \
        --entity-type topics \
        --entity-name digital-onboarding \
        --add-config retention.hours=24
    

    bin/kafka-configs.sh \
        --zookeeper 192.168.163.71:2181 \
        --alter \
        --entity-type topics \
        --entity-name digital-lengid  \
        --add-config retention.hours=168
    

    一旦更改,您可以通过描述主题来验证配置是否有效:

    bin/kafka-topics.sh \
        --zookeeper 192.168.163.71:2181 
        --describe \
        --topic digital-onboarding
    

    新的保留政策应列在Configs:

    【讨论】:

    • 嗨。谢谢!我不想更改保留时间。我需要了解为什么一个主题需要 1 天,而另一个主题需要 7 天。请再读一遍我的问题。
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