8 Replies Latest reply on Jan 9, 2019 1:51 AM by Fiona Tan

    Tableau Prep - JAVA Heap Space Error

    Adam Langenderfer

      I have re-created an Alteryx flow in Tableau Prep in which everything works fine until I go to output a file.  Upon running the output flow - it begins to execute and then after 20 seconds, I get an error: "System Error: Java Heap Space".  It does not matter if i try .csv, .tde, or ,.hyper for the output type, I get he same results. I have also tried running as an un-packaged flow and as a packaged flow, still with no luck. Alteryx can run the exact same flow in under a min with no issues.  Any suggestion on how to get this to work in Prep?


      Note: My computer is 64 bit/ 8 GB RAM/ Win 7.  I have 5 files I am using for inputs (all excel), two of which are around 40 MB and the others around 1 or 2 MB.

        • 1. Re: Tableau Prep - JAVA Heap Space Error
          Arthur Gyldenege

          Thank you for raising this issue Adam! Would you be able to share a copy of your log files and a tflx of your flow so we can see what's happening?


          Below are the instructions for collecting and sending your log files if you're able to.


          Where are the log files?

          • Windows: C:\Users\<your username>\Documents\My Tableau Prep Repository\Logs
          • Mac: /Users/<your username>/My Tableau Prep Repository/Logs


          Steps to collect log files

          1. Clear out your logs:  Go to your user directory and delete all files there.
          2. Recreate the issue: Open Tableau Prep and recreate the issue
          3. Close Tableau Prep
          4. Zip up all the new log files
          5. Attach the zip file and reply to this thread, or respond to me directly if you prefer
          • 2. Re: Tableau Prep - JAVA Heap Space Error
            Brook Moles

            I'm having the same problem, apart from having first created an Alteryx flow.


            How can I send you my files directly, Arthur?


            Here's what I got at the end of U_13264.log:


            [2018-08-01T00:12:58.483] BackendManager: got GET request for health checking, returning 200

            [2018-08-01T00:13:03.808] restApi:

            [2018-08-01 00:13:03,809] 10464@CIS1JZ0SN12 54936 [pool-2-thread-1] p: DEBUG com.tableau.loom.cache.CachingMaterializationManager - Finished cache operation 94aa97b1-4710-4251-8bcf-b9eeba5f6f10


            [2018-08-01T00:13:03.814] restApi:

            INFO: Initializing Spring embedded WebApplicationContext

            java.util.concurrent.ExecutionException: com.tableau.loom.lang.api.exceptions.LangSystemException: System error: Java heap space


            [2018-08-01T00:13:03.815] restApi:

            at com.tableau.loom.runtime.FlowEvaluationJobCompletion.get(FlowEvaluationJobCompletion.java:84)


            [2018-08-01T00:13:03.815] restApi:

            at com.tableau.loom.runtime.FlowEvaluationJobCompletion.get(FlowEvaluationJobCompletion.java:34)

            at com.tableau.loom.execution.engine.FlowRunner.call(FlowRunner.java:53)

            at com.tableau.loom.execution.engine.FlowRunner.call(FlowRunner.java:35)

            at java.util.concurrent.FutureTask.run(FutureTask.java:266)


            [2018-08-01T00:13:03.816] restApi:

            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)

            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)

            at java.lang.Thread.run(Thread.java:748)

            Caused by: com.tableau.loom.lang.api.exceptions.LangSystemException: System error: Java heap space

            at com.tableau.loom.runtime.EvaluationInstance.waitForFlow(EvaluationInstance.java:207)

            at com.tableau.loom.runtime.FlowEvaluationJobCompletion.get(FlowEvaluationJobCompletion.java:70)


            [2018-08-01T00:13:03.816] restApi:

            ... 7 more

            Caused by: java.lang.OutOfMemoryError: Java heap space

            at java.util.Arrays.copyOf(Arrays.java:3332)

            at java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.java:124)

            at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:596)

            at java.lang.StringBuffer.append(StringBuffer.java:367)

            at java.io.StringWriter.write(StringWriter.java:94)



            [2018-08-01T00:13:12.690] App: stopping backend

            • 3. Re: Tableau Prep - JAVA Heap Space Error
              Brook Moles

              PS: I'm running Windows 10, Java (32 bit) version 8 update 131.


              When I increase the heap size by setting the -Xms####m runtime parameter, it takes longer for the flow to bomb, but it still does. I've gone up to 4g (4096m).


              For what it's worth, here's a screenshot of the cpu and memory utilization from when the flow was running.

              Java resource use.PNG

              • 4. Re: Tableau Prep - JAVA Heap Space Error
                Adam Langenderfer

                Update:  I tried converting the two largest input files from excel into Tableau .Hyper files to see if that would help – it did not.
                Additionally, I increased the Heap in Java to its max – after doing so I got a new error of Java GC overhead limit exceeded.  I am attaching my Log file. (unable to attach packed flow due to sensitive data)


                Also similar to what Brook made mention of with her screen shot, the CPU memory for both Java and Prep go through the roof during processing.

                • 5. Re: Tableau Prep - JAVA Heap Space Error
                  Alessandro Pini

                  I have the same Issue, using macOS High Sierra 10.13.5 and Tableau Prep 2018.1.2

                  When the flow starts, suddenly the memory occupied by Java passes from 900MB to 2.2GB and the flow stop working.

                  It's happening since one week when the same flow was working before.


                  Attached my Prep Logs and a screenshot.

                  Screen Shot 2018-08-03 at 17.20.16.png


                  Please check as soon as possible, because a problem of this kind makes the flow unusable and it is impossible to proceed with the work.

                  Thank You

                  • 6. Re: Tableau Prep - JAVA Heap Space Error
                    Alessandro Pini

                    Workaround: clicking on one of the last steps before the output (by loading the data of the step) and then making the output the problem related to "java heap space" does not occur.

                    • 7. Re: Tableau Prep - JAVA Heap Space Error
                      Adam Langenderfer

                      @Alessandro Pini -  this did not work for me, unfortunately.

                      • 8. Re: Tableau Prep - JAVA Heap Space Error
                        Fiona Tan

                        Did anyone found a solution to this? I am running into the same issue here. Tableau Prep flow works fine when i output as local extract, but when I try to publish as data source to Tableau Online, I get this error.