kafka多執行緒消費topic的問題

案例：

topic：my-topic，分割槽：6

消費者：部署三颱機器，每台機器上面開啟6個執行緒消費。

消費結果：只有一台機器可以正常消費，另外兩台機器直接輸出六條告警日誌：

no broker partitions consumed by consumer thread my-topic-group_adfc6be4a509-1496976531798-d70f9a43-3 for topic my-topic

no broker partitions consumed by consumer thread my-topic-group_adfc6be4a509-1496976531798-d70f9a43-1 for topic my-topic

no broker partitions consumed by consumer thread my-topic-group_adfc6be4a509-1496976531798-d70f9a43-2 for topic my-topic

no broker partitions consumed by consumer thread my-topic-group_adfc6be4a509-1496976531798-d70f9a43-4 for topic my-topic

no broker partitions consumed by consumer thread my-topic-group_adfc6be4a509-1496976531798-d70f9a43-6 for topic my-topic

no broker partitions consumed by consumer thread my-topic-group_adfc6be4a509-1496976531798-d70f9a43-5 for topic my-topic

在原始碼分析之前，先給個圖示吧，花了兩個小時才畫完。

原始碼分析：

for (topic }}
}

結果：topic裡面的每個partition只會由乙個執行緒消費，在分配的時候就已經指定好，如果有消費者執行緒加入或者退出，則會重新開始分配。