Hi, If tasks end up in the same TaskManager, they us LocalInputChannel(s), which does not go through network, but reads directly from local partitions.
I am also pulling in @Piotr who might give you some more insights, or correct me if I am wrong. [1] https://ci.apache.org/projects/flink/flink-docs-release-1.12/api/java/org/apache/flink/runtime/io/network/partition/consumer/LocalInputChannel.html Best, Dawid On 26/01/2021 08:18, ?????? wrote: > Hi, > > I'm confused about slots communication in same taskmanager. > > Assume only one job which running on per-job cluster with parallalism?0?2= 6. > Each taskmanager with 3 slot. > There are 6 slot:?0?2 > slot 1-1, slot 1-2, slot 1-3,?0?2?0?2 > slot 2-1, slot 2-2 , slot 2-3 > > Assume the job has 'KeyBy' operator, thus, eash 'keyby' in each slot > will distribute data into?0?2 > all downstream opeators in every slots. > > I know that?0?2 > > Tasks in the same JVM share TCP connections (via multiplexing) and > heartbeat messages > > That means: > slot 1-1 , slot 1-2, slot 1-3 share TCP connections communicate with > slot 2-1, slot 2-2, slot 2-3 > > My question is: > > how about communication type between slot 1-1 and slot 1-2? > by thread-to-thread? > or by network?
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