Investigating Slow View Load Requests
The Slow View Load Requests chart on the performance page is a useful metric to understand the performance of views and the resulting impact on user interactions on Tableau Server.
The Slow View Load Requests chart shows when views are rendering more slowly than normal on Tableau Server. To do this, the chart uses a baseline that is established for each view and is then uses it to compare the time it takes to render that view to determine if the view is taking longer than expected.
In version 2021.4, the baseline is established by calculating the median value of the first 10 times a specific workbook is rendered successfully.
In version 2021.4.1 and later, the baseline is established by calculating the 95th percentile of 50 times a specific workbook is rendered successfully.
Once the baseline is established, every time that same workbook is rendered in the future, the time taken for a workbook to load is then compared to its baseline. Depending on whether the time taken to render the view falls within the expected range or at varying degrees outside of the expected range, they are categorized as follows:
- Normal: <=2x baseline
- Long: >=2x baseline
- Very Long: >=4x baseline
- Failed: Failed to load or resulted in an error
Note: This baseline and the comparisons only apply to initial rendering of the view. It does apply to subsequent actions like filter selections. Also, when you publish a new version of the workbook, it triggers a recalculation of the baseline.
The chart shows the percentage of view loads that are outside of the normal range for the selected time range. So, if you see yellow (Long) or red (Very Long) spikes on this chart, that is the first indication that there is likely a problem.
Tip: Selecting the “Past 48 hours” time range might be a good place to start as it will give you some context on activity in the past versus current.
The Concurrent Users and the Total View Load Requests charts on the same page can be used to see the scope of the impact resulting from slow view loads in the same time range. You can also use the Tableau Processes chart to identify any correlations between the slow view load performance and resource usage - like for example, you might see high VizQL Server resource usage on specific nodes during the same time that you are seeing spikes in the Slow View Load Requests chart.
If you see a spike in the slow view load request chart, you can then start to drill down further to identify what might be causing the issue - whether the problem is due to a single view or a much broader issue. To do this, within the Slow View Load Requests chart, select a range to include a large portion of the slow views. This will take you to the View Loads activity page, showing you view load requests for the same time frame.
Filter by Load Time Severity Category and select the appropriate category for the view loads you want to investigate.
The list should indicate which views might have caused the chart results and can be understood in the following ways:
Multiple views: If the list shows multiple views, this is likely a broader issue with Tableau Server. Go back to the performance page, and take a look at the Performance, and Tableau Server Processes chart to investigate the resource usage. The Status tab on the performance page will show the status of the processes whether they are active, busy, or down. Look for the VizQL Server, Data Server, and the Data Engine processes on this list.
Same view: If the list is mostly one single view, this could mean that there is an issue with that view or workbook. Further investigation might be needed to see what might be causing the problem. Click on the view name in the list to see more information about load times, related data queries, and VizQL sessions.
Important! On the Load Times chart, if the average load time is consistent even when adjusting the date range to span just before and after the spike began, it means that the baseline calculation was likely created when view loads were heavily cached, causing subsequent view loads to be considered 'slow'. This scenario does not reflect an issue with Tableau Server or the view. If this is the case, you can trigger a recalculation of the baseline by publishing a new version of the workbook.
Here are some resources to help with performance troubleshooting for a specific view:
Who can do this
Any Resource Monitoring Tool user can view the charts.