ChenLin created KAFKA-8328:
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Summary: Kafka smooth expansion
Key: KAFKA-8328
URL: https://issues.apache.org/jira/browse/KAFKA-8328
Project: Kafka
Issue Type: Improvement
Components: clients, core
Affects Versions: 0.10.2.0
Reporter: ChenLin
Fix For: 0.10.2.0
Attachments: DiskUtil.png, producerP999.png
When expanding the kafka cluster, the new follower will read the data from the
earliest offset. This can result in a large amount of historical data being
read from the disk, putting a lot of pressure on the disk and affecting the
performance of the kafka service, for example, the producer write latency will
increase. In general, kafka's original expansion mechanism has the following
problems:
1. The new follower will put a lot of pressure on the disk;
2. Causes the producer write latency to increase;
3. Causes the consumer read latency to increase;
In order to solve these problems, we have proposed a solution for smooth
expansion. The main idea of the scheme is that the newly added follower reads
data from the HW position, and when the newly added follower reads the data to
a certain time threshold or data size threshold, the follower enters the ISR
queue. . Since the new follower reads data from the HW location, most of the
data read is in the operating system's cache, so it does not put pressure on
the disk and does not affect the performance of the kafka service, thus solving
the above problems. problem.
In order to illustrate the problems of the original expansion scheme, we
have done some tests, and there are corresponding test charts in the attachment.
!image-2019-05-07-14-12-41-314.png! !image-2019-05-07-14-12-03-005.png!
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