A little bit about Power BI Diagnostics

Gilbert Quevauvillie from FourMoo posted a great blog post identifying all of the different processes that are running when you have Power BI running.

He identifies four different processes that you will see running and a quick blurb on each.  I wanted to post a quick follow up to show how the diagnostic logging in Power BI captures output from these processes.

Power BI Desktop has diagnostic logs?  Absolutely!

To turn on the logging, enable it from your options as follows:

There is a link that you can click on that will take you directly to the traces folder in case you aren’t the type to memorize logging locations for software.

When you open this folder, \%username%\AppData\Local\Microsoft\Power BI Desktop\Traces, there are actually two sets of logs.  The first set is stored directly in this folder and they will only be created once you turn on tracing.

If you open the Performance folder that is in this directory, you will see that Power BI Desktop actually is ALWAYS logging.  I am fairly certain that these are a rolling set of logs that are captured in case of an unexpected failure.  When Power BI crashes, it will create a FrownSnapShot zip file and a PerformanceTraces.zip file.  The latter is a zip of the Performance folder.  The FrownSnapShot zip file is pretty cool because it contains the latest SQL Flight Recorder data that has been captured.  Interestingly enough, the FrownSnapshot zip also includes a file called ASPPerfCounters.json which looks like Perfmon data that is dumped into a JSON file.  Interesting……

The log files that you will find in the Traces folder are as follows.

  1.  PBIDesktop.<version>.TimeStamp
    • This file logs information for the Power BI Desktop Application.
  2.  Microsoft.Mashup.Container.NetFX45.<version>.<TimeStamp>
    • This log appears once you go into the Query Editor or refresh your data.  This is where Power Query actions are logged during the processing and cleaning of your data.
    • Once you start a data refresh in Power BI Desktop, you will see multiple log files that start with this name.  I am going to assume that Power BI Desktop will spin up multiple Power Query engines as necessary and each will have its own log file.
  3.  MSMDSRV.<version>.TimeStamp
    • From my experience, you will only see this log if an exception is captured by the SSAS engine in Power BI Desktop.  For instance, I saw this log appear when I was troubleshooting a crash that was occurring during data refresh.  This log is also included in the FrownSnapshot zip that is created during a crash.

If you have questions about Power BI Logging or want to add corrections, please leave me a comment!



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