Hi Lasantha，
Thanks for your reply.I also found the method call chain you said. Next, I'm going to study these codes to see if I can modify them to schedule tasks to a slot in the specified taskManager. But I think it's a very difficult thing for me to read the source code, especially in the absence of comments. It would be a great pleasure if more people come to study and discuss this topic. Best, Penguin At 2021-01-08 06:58:54, "Lasantha Fernando" <lasantha....@gmail.com> wrote: >Hi Penguin, > >Jumping into this conversation since I worked on the same code base >(Flink-1.11.2) for a recent project and might have a more fresh memory of >the method calls. > >I believe the chain of methods you have highlighted is correct. Obviously, >the chain would differ based on the configuration and context. This is a >stack trace that I derived for a scheduling call for a simple Word Count >streaming application. > >selectBestSlotForProfile:46, LocationPreferenceSlotSelectionStrategy >(org.apache.flink.runtime.jobmaster.slotpool) >tryAllocateFromAvailable:275, SchedulerImpl >(org.apache.flink.runtime.jobmaster.slotpool) >allocateMultiTaskSlot:470, SchedulerImpl >(org.apache.flink.runtime.jobmaster.slotpool) >allocateSharedSlot:311, SchedulerImpl >(org.apache.flink.runtime.jobmaster.slotpool) >internalAllocateSlot:160, SchedulerImpl >(org.apache.flink.runtime.jobmaster.slotpool) >allocateSlotInternal:143, SchedulerImpl >(org.apache.flink.runtime.jobmaster.slotpool) >allocateSlot:113, SchedulerImpl >(org.apache.flink.runtime.jobmaster.slotpool) >allocateSlot:115, SlotProviderStrategy$NormalSlotProviderStrategy >(org.apache.flink.runtime.executiongraph) >lambda$allocateSlotsFor$0:104, DefaultExecutionSlotAllocator >(org.apache.flink.runtime.scheduler) >apply:-1, 90274328 >(org.apache.flink.runtime.scheduler.DefaultExecutionSlotAllocator$$Lambda$679) >uniComposeStage:995, CompletableFuture (java.util.concurrent) >thenCompose:2137, CompletableFuture (java.util.concurrent) >allocateSlotsFor:102, DefaultExecutionSlotAllocator >(org.apache.flink.runtime.scheduler) >allocateSlots:339, DefaultScheduler (org.apache.flink.runtime.scheduler) >allocateSlotsAndDeploy:312, DefaultScheduler >(org.apache.flink.runtime.scheduler) >allocateSlotsAndDeploy:76, EagerSchedulingStrategy >(org.apache.flink.runtime.scheduler.strategy) >startScheduling:52, EagerSchedulingStrategy >(org.apache.flink.runtime.scheduler.strategy) >startSchedulingInternal:173, DefaultScheduler >(org.apache.flink.runtime.scheduler) >startScheduling:461, SchedulerBase (org.apache.flink.runtime.scheduler) >startScheduling:897, JobMaster (org.apache.flink.runtime.jobmaster) > >It might be useful to remote debug a local setup to get the exact stack >trace/method-call-chain for your scenario. Navigating the code through >method calls to figure out the execution sequence can be a bit tricky since >Flink uses a lot of asynchronous calls. > >According to my understanding, the basic flow for scheduling goes like >this: It initially calls DefaultScheduler#startScheduling, and goes through >an internal call to the preset scheduling strategy. The scheduling strategy >is set at the time of creation of the DefaultScheduler class. The >scheduling strategy basically populates some deployment option >configurations (though it can be used to do more fine-grained scheduling >changes), then tells the DefaultScheduler to allocate the slots and deploy. >It then goes through another set of calls that basically allocates slots, >selects a slot for each execution vertex (while also considering slot >selection strategies). > >This information is then sent to the TaskManager through an RPC call >(through another set chain of calls), and the task information is used by >the task manager to deploy the tasks according to the schedule. > >Hope this helps. Also hope someone from the community will correct if I >have stated something incorrect. > >Best, > >Lasantha > >On Wed, 6 Jan 2021 at 21:01, penguin. <bxwhfh...@126.com> wrote: > >> Hi Till, >> >> Thank you for your reply. I found such a chain of method calls: >> >> >> JobMaster#startScheduling -> SchedulerBase#startScheduling -> >> DefaultScheduler#startSchedulingInternal -> >> EagerSchedulingStrategy#startScheduling -> >> EagerSchedulingStrategy#allocateSlotsAndDeploy -> >> DefaultScheduler#allocateSlotsAndDeploy . >> (The version of Flink I use is Flink-1.11.1) >> >> >> I'm going to try to see the following code first, but the code annotation >> seem to be very few.I feel very difficult for my goal and I hope I can get >> your help later. >> >> >> Sincerely, >> Penguin >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> At 2021-01-06 17:08:05, "Till Rohrmann" <trohrm...@apache.org> wrote: >> >Hi Penguin, >> > >> >What do you wanna do? If you want to change Flink's scheduling behaviour, >> >then you can take a look at the implementations of SchedulerNG. >> > >> >Cheers, >> >Till >> > >> >On Wed, Jan 6, 2021 at 6:58 AM penguin. <bxwhfh...@126.com> wrote: >> > >> >> Hello! Do you know how to modify the task scheduling method of Flink? >>
