Kafka 日志压缩未开始

Question

我有一个主题，描述如下：

Topic:test-topic    PartitionCount:1    ReplicationFactor:1 Configs:min.cleanable.dirty.ratio=0.01,min.compaction.lag.ms=86400000,cleanup.policy=compact
    Topic: test-topic   Partition: 0    Leader: 1   Replicas: 1 Isr: 1

我的经纪人有 log.cleaner.enable=true

该主题有 870778 条消息，其中存在大量重复键（有些达到数千个重复键）。根据 Kafka docs 的说法，Kafka 应该在这些条件下部署日志压缩，并使用给定密钥修剪除最新消息之外的所有消息。这不会在几周后发生，如果不是几个月的话。我在这里缺少什么来启动日志压缩？

代理配置：

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# 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
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# 
#    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

############################# Socket Server Settings #############################

# The port the socket server listens on
port=<port>

# Hostname the broker will bind to. If not set, the server will bind to all interfaces
#host.name=localhost

# Hostname the broker will advertise to producers and consumers. If not set, it uses the
# value for "host.name" if configured.  Otherwise, it will use the value returned from
# java.net.InetAddress.getCanonicalHostName().
#advertised.host.name=<hostname routable by clients>

# The port to publish to ZooKeeper for clients to use. If this is not set,
# it will publish the same port that the broker binds to.
#advertised.port=<port accessible by clients>

# The number of threads handling network requests
num.network.threads=8

# The number of threads doing disk I/O
num.io.threads=8

# The send buffer (SO_SNDBUF) used by the socket server
socket.send.buffer.bytes=1048576

# The receive buffer (SO_RCVBUF) used by the socket server
socket.receive.buffer.bytes=1048576

# 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=<dir-path>

# 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=30

############################# 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=20000
inter.broker.protocol.version=0.8.2.0
log.message.format.version=0.8.2.0

# The maximum amount of time a message can sit in a log before we force a flush
log.flush.interval.ms=10000
message.max.bytes=1000000
auto.create.topics.enable=false
log.index.interval.bytes=4096
log.index.size.max.bytes=10485760
log.flush.scheduler.interval.ms=2000
log.roll.hours=24
log.retention.check.interval.ms=300000
log.segment.bytes=1073741824
############################# 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=24

# 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=1073741824

# The maximum size of a log segment file. When this size is reached a new log segment will be created.
log.segment.bytes=536870912

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

# 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=true

default.replication.factor=3
num.replica.fetchers=4
replica.fetch.max.bytes=1048576
replica.fetch.wait.max.ms=2000
replica.high.watermark.checkpoint.interval.ms=5000
replica.socket.timeout.ms=60000
replica.socket.receive.buffer.bytes=65536
replica.lag.time.max.ms=30000
replica.lag.max.messages=12000

controller.socket.timeout.ms=60000
controller.message.queue.size=20

auto.leader.rebalance.enable=true
leader.imbalance.per.broker.percentage=5
leader.imbalance.check.interval.seconds=300

############################# 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=<connection-string>

# Timeout in ms for connecting to zookeeper
zookeeper.connection.timeout.ms=1000000
#zk.sync.time.ms=2000

kafka.metrics.reporters=com.airbnb.kafka.KafkaStatsdMetricsReporter

# enable the reporter, (false)
external.kafka.statsd.reporter.enabled=true

# the host of the StatsD server (localhost)
external.kafka.statsd.host=statsd
# the port of the StatsD server (8995)
external.kafka.statsd.port=<port>

# a prefix for all metrics names (empty)
external.kafka.statsd.metrics.prefix=<connection-string>

Answer 1

要运行压缩，您需要至少有 2 个段文件（一个已完成，一个正在运行）。

根据你的配置

log.segment.bytes=1073741824
log.segment.bytes=536870912

（请检查为什么您有两个相同的属性）。

您需要有一个 512Mb 的完整文件，以便 kafka 可以在其上运行压缩。请检查您是否有至少 2 个要压缩的主题分区的段文件

Answer 2

正如 Natalia 所说，我们可以log.segment.bytes config 根据大小确定日志段文件滚动。

如果您不想更改log.segment.bytes（或）您不想等到日志段达到其完整大小，您可以使用log.segment.ms 配置按时间滚动日志段文件并触发压缩。

Answer 3

“Kafka 应该在这些条件下部署日志压缩，并使用给定密钥修剪除最新消息之外的所有消息。”

这似乎是 Kafka 日志压缩的主要误解之一。在Log Compaction 的 Kafka 文档中指出

“日志压缩确保 Kafka 将始终为单个主题分区的数据日志中的每个消息键保留至少最后一个已知值。”

不保证压缩主题中没有重复的键。正如其他答案中所提到的，仔细研究将数据物理存储到日志/段中是至关重要的。在LogCleaner class 中，您可以找到对 clean 和 dirty 段之间区别的很好解释：

如果存在具有键 K 和偏移量 O' 使得 O

日志压缩提供的保证在Kafka documentation 和最重要的configurations 中给出，以控制清理器：

1) To activate compaction cleanup policy cleanup.policy=compact should be placed

2) The consumer sees all tombstones as long as the consumer reaches head of a log in a period less than the topic config delete.retention.ms (the default is 24 hours).

3) The number of these threads are configurable through log.cleaner.threads config

4) The cleaner thread then chooses the log with the highest dirty ratio. dirty ratio = the number of bytes in the head / total number of bytes in the log(tail + head)

5) Topic config min.compaction.lag.ms gets used to guarantee a minimum period that must pass before a message can be compacted.

6) To set delay to start compacting records after they are written use topic config log.cleaner.min.compaction.lag.ms. Records won’t get compacted until after this period. The setting gives consumers time to get every record.