Hi Buvana, A TaskManager runs as a single JVM process. A TaskManager provides a certain number of processing slots. Slots do not guard CPU time, IO, or JVM memory. At the moment they only isolate managed memory which is only used for batch processing. For streaming applications their only purpose is to limit the number of parallel threads that can be executed by a TaskManager.
In each processing slot, a full slice of a program can be executed, i.e., one parallel subtask of each operator of a program. Given a simple program (source -> map -> sink), a slot can process one subtask of the source, the mapper, and the sink (it is possible to split a program to be executed in more slots). Each operator can be executed as a separate thread. However, in many situations, operators are chained within the same thread to improve performance (again it is possible to disallow chaining). Let me know if you have more questions, Fabian 2016-09-26 20:31 GMT+02:00 Ramanan, Buvana (Nokia - US) < buvana.rama...@nokia-bell-labs.com>: > Hello, > > > > I would like to understand the following better: > > > > https://ci.apache.org/projects/flink/flink-docs- > release-1.1/setup/config.html#configuring-taskmanager-processing-slots > > > > Fundamental question – what is the notion of Task Slot? Does it correspond > to one JVM? Or the Task Manager itself corresponds to one JVM? > > Example-1 shows a parallelism of 1 and has 3 operators – flatMap, Reduce & > Sink. Here comes the question – are these 3 operators running a separate > threads within a JVM? > > > > Sorry for the naïve questions. I studied the following links and could not > get a clear answer: > > https://ci.apache.org/projects/flink/flink-docs- > release-1.1/internals/general_arch.html > > https://ci.apache.org/projects/flink/flink-docs-release-1.1/internals/job_ > scheduling.html > > > > Are there more documents under Flink’s wiki site / elsewhere? Please point > me to more info on the architecture. > > > > thank you, > > regards, > > Buvana > > >
