Hi Pankaj, That's really a good question. There was a refactor of architecture before[1]. So there might be some descriptions used the outdated concept.
Before refactoring, Job Manager is a centralized role. It controls whole cluster and all jobs which is described in your interpretation 1. After refactoring, the old Job Manager is separated into several roles, Resource Manager, Dispatcher, new Job Manager, etc. The new Job Manager is responsible for only one job, which is described in your interpretation 2. So the document you refer to is outdated. Would you mind telling us the URL of this document? I think we should update it to avoid misleading more people. 1. https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=65147077 Eduardo Winpenny Tejedor <eduardo.winpe...@gmail.com> 于2019年6月19日周三 上午1:12写道： > Hi Pankaj, > > I have no experience with Hadoop but from the book I gathered there's one > Job Manager per application i.e. per jar (as in the example in the first > chapter). This is not to say there's one Job Manager per job. Actually I > don't think the word Job is defined in the book, I've seen Task defined, > and those do have Task Managers > > Hope this is along the right lines > > Regards, > Eduardo > > On Tue, 18 Jun 2019, 08:42 Pankaj Chand, <pankajchanda...@gmail.com> > wrote: > >> I am trying to understand the role of Job Manager in Flink, and have come >> across two possibly distinct interpretations. >> >> 1. The online documentation v1.8 signifies that there is at least one Job >> Manager in a cluster, and it is closely tied to the cluster of machines, by >> managing all jobs in that cluster of machines. >> >> This signifies that Flink's Job Manager is much like Hadoop's Application >> Manager. >> >> 2. The book, "Stream Processing with Apache Flink", writes that, "The >> Job Manager is the master process that controls the execution of a single >> application—each application is controlled by a different Job Manager." >> >> This signifies that Flink defaults to one Job Manager per job, and the >> Job Manager is closely tied to that single job, much like Hadoop's >> Application Master for each job. >> >> Please let me know which one is correct. >> >> Pankaj >> >
