num.stream.threads 创建空闲线程

Question

我有一个 spring boot kafka stream 应用程序，有 2 个主题，考虑主题 A 和 B.Topic A 有 16 个分区，主题 B 有 1 个 partition.Consider 应用程序部署在 1 个实例中num.stream.threads=16。 我 运行 kafka-consumer-groups.bat 命令检查线程如何分配给组中的分区，得到以下 output.Topic A 和 B 分配了 16 个线程，其中主题 B 中有 14 个线程空闲。

kafka-consumer-groups.bat --bootstrap-server 0.0.0.0:9092 --group <topic-AGroupName>  -describe
TOPIC     PARTITION      CLIENT-ID
topic-A    0          topic-AGroupStreamThread-429-consumer
topic-A    10         topic-AGroupStreamThread-422-consumer
topic-A    6          topic-AGroupStreamThread-425-consumer
topic-A    14         topic-AGroupStreamThread-431-consumer
topic-A    7          topic-AGroupStreamThread-420-consumer
topic-A    8          topic-AGroupStreamThread-428-consumer
topic-A    11         topic-AGroupStreamThread-430-consumer
topic-A    4          topic-AGroupStreamThread-417-consumer
topic-A    2          topic-AGroupStreamThread-427-consumer
topic-A    1          topic-AGroupStreamThread-418-consumer
topic-A    15         topic-AGroupStreamThread-421-consumer
topic-A    3          topic-AGroupStreamThread-424-consumer
topic-A    9          topic-AGroupStreamThread-419-consumer
topic-A    12         topic-AGroupStreamThread-426-consumer
topic-A    13         topic-AGroupStreamThread-432-consumer
topic-A    5          topic-AGroupStreamThread-423-consumer

kafka-consumer-groups.bat --bootstrap-server 0.0.0.0:9092 --group <topic-BGroupName>  -describe
TOPIC                               PARTITION                    CLIENT-ID
topic-BGroup-result-repartition     0            topic-BGroupStreamThread-683-consumer
topic-B                             0            topic-BGroupStreamThread-678-consumer
-                                   -            topic-BGroupStreamThread-685-consumer
-                                   -            topic-BGroupStreamThread-675-consumer
-                                   -            topic-BGroupStreamThread-673-consumer
-                                   -            topic-BGroupStreamThread-680-consumer
-                                   -            topic-BGroupStreamThread-688-consumer
-                                   -            topic-BGroupStreamThread-674-consumer
-                                   -            topic-BGroupStreamThread-679-consumer
-                                   -            topic-BGroupStreamThread-677-consumer
-                                   -            topic-BGroupStreamThread-687-consumer
-                                   -            topic-BGroupStreamThread-686-consumer
-                                   -            topic-BGroupStreamThread-676-consumer
-                                   -            topic-BGroupStreamThread-684-consumer
-                                   -            topic-BGroupStreamThread-682-consumer
-                                   -            topic-BGroupStreamThread-681-consumer

如何避免主题 B 中的空闲线程，或者是否有任何选项可用于为每个主题设置 num.stream.threads？

Answer 1

您可以在实际输入绑定上设置并发性属性。例如spring.cloud.stream.kafka.streams.bindings.<input-binding-name>.consumer.concurrency。每个输入绑定都会在幕后映射到 num.stream.threads。看看这是否有效，如果您发现任何问题，请告诉我们。