8 Replies Latest reply on Feb 1, 2018 10:53 AM by Toby Erkson

    Background Task Delays- Wait Time

    kbj3030

      Hi All,

       

      We have 2 extracts which run on daily basis. From few days, I see them waiting for 9-10 hrs and then starting to run.

       

      Below is the analysis done from my side

       

      1. I went through the logs to find out the reason but couldn't trace.

      2. The extracts were optimized with best practices where we can't fix anything from development end.

      3. There are no other parallel jobs running at that time and bg resources are fairly available

       

      One more important observation was

      - The backgrounder Id changes from the time it gets picked and when it completes to run the job.

      For Eg: Say Extract A picked by Bg Id: 10.10.10.10 @ Created at. It waits for 9-10 hrs and jumps to Bg Id : 10.10.10.11 @ Started at.

       

      We are using Tableau 10.4.0 and SAS datasource. Request you to please help me in figuring out the issue.

       

      Let me know if you require any additional details. Thanks!

        • 1. Re: Background Task Delays- Wait Time
          Toby Erkson

          The priority set for the Task could be too low, thus other Tasks jump in line ahead of them.

           

          There can be tasks running prior to your refresh jobs that can consume resources.

          Just curious, are you using a single-node or multi-node Tableau Server environment?  How many backgrounders?

          • 2. Re: Background Task Delays- Wait Time
            kbj3030

            Hi Toby,

             

            Thanks for your reply.

             

            -The priority of the task was set to 1. So, its not priority issue

            - Yes, there are tasks running prior to this extract but I see the bg resources are fairly available for this task to pick up and run. So, hope it is not the resource consumption

            - We are using multi node Tableau Server Environment with 2bg's in worker 1,2bg's in worker 2 and 4bg's in worker 3. So, the total of 8 bg's

            • 3. Re: Background Task Delays- Wait Time
              Toby Erkson

              How much RAM & hard drive space on each worker?  Depending upon the complexity and size, if the memory to work with is limited then the hard drive will get used a lot more and that can slow things down.

               

              From the 10.5 manual:

              Note: In versions earlier than 10.5, the backgrounder process spun up temporary instances of Data Engine when refreshing extracts. In 10.5, a single instance of Data Engine is installed during setup with the Backgrounder process. The backgrounder uses this running instance of Data Engine when refreshing extracts.

              If you don't have a Data Engine with each worker that contains backgrounders maybe you should add one Data Engine to each worker (I know you are running 10.4).

               

              Can you increase the number of backgrounders, even if it's just by +1?  With dedicated workers for backgrounders you could use the n ÷ 2 formula instead of n ÷ 4.

              • 4. Re: Background Task Delays- Wait Time
                kbj3030

                Hi Toby,

                 

                Thanks for the info. We use 64GB RAM and 1TB hard drive space on each worker. We have Data Engines added for worker 1&2 but not Worker 3(dedicated to bg's). Do you want me to add DE instances even for 3rd worker as well to fix this issue?

                • 5. Re: Background Task Delays- Wait Time
                  Toby Erkson

                  According to the documentation a DE is spun up when required by a backgrounder and in version 10.5 there will be a DE if a server has a backgrounder present...so why not just put it there.  I don't know if this will help but it's something to try. 

                   

                  It sounds like you have enough memory space (RAM & hard drive) so I'm out of ideas.  You may want to contact Tableau Support if others can't help.

                  Jeff Strauss  Glauber Ribeiro John Kuo

                  • 6. Re: Background Task Delays- Wait Time
                    kbj3030

                    Sure Toby. Thanks for providing your inputs on this. I will try to implement and update you.

                    • 7. Re: Background Task Delays- Wait Time
                      kbj3030

                      Hi Toby,

                       

                      I tracked the extracts that run from worker 1&2 which holds bg's and DE together. Still I see the same wait time issue :-( . So, I guess adding DE instances in 3 rd worker will not resolve the issue.

                      • 8. Re: Background Task Delays- Wait Time
                        Toby Erkson

                        Bummer   Please let us know what Tableau Support's answer is when you get it.