NAV Team: Memory usage in Microsoft Dynamics NAV 2013 print preview

[Blog bot]

Periodically we receive requests where customers asking us about RTC print preview consumes all available memory and computers hangs.

Repro scenarios are more/less similar: run report, click preview, go per pages up/down, close report. Run another report, click preview, go per pages up down and… RTC hangs.
If we look to memory usage, NAV is using all available memory.

If we analyze what has happened, we see: with every move per pages memory usage increase and increase and increase until all memory is used.
It looks like typical memory leak because in NAV 2009 with the same repro everything is OK.

However it is not so simple. What NAV does in this scenario is: it loads Microsoft Report Viewer 2010 with 2 files: report definition (RDL file where is described report structure) and record set. And that is all, next actions like preview/print/export are managed by report viewer. The same we have in NAV 2009 just it loads Report Viewer 2008 and .NET Framework 3.5 as NAV 2013 uses Report Viewer 2010 and .NET Framework 4.5. And here is reason pointing us to memory usage behavior: Report Viewer 2010 and .NET 4.5 uses another way to manage memory (named more advanced and more secure). However this ‘another’ way gets us mentioned questions from customers and really we can do nothing from NAV platform side – system works as it is designed to work.

But things are not so bad. In .NET memory is managed very smart and not used memory is released by function named ‘garbage collector’. This function periodically review memory blocks and release not used. And actually it works: if we monitor memory during report previewing and after it close we see that in preview and going per pages memory usage increase, after preview close memory usage is still the same, but after 5-10 min used memory decrease to initial numbers. For example in my tests started RTC using 98.5 MB, after few previews and scrolls and etc. usage increases to 215 MB and doesn’t decrease if I close preview. But after few minutes garbage collector returns usage to 100.4 MB.
We can force (in NAV platform) garbage collector to work faster and memory release will be faster, but this will increase processor usage and in many cases it is worse than memory usage.

Few trick could help users do not meet memory problems:

1. When we open report preview we see report in “funny” interactive mode. This is preview mode where we can change report view in some way described in report code. For example in report ‘Customer – Top 10 List’ sorting can be changed. But exactly this mode is memory monster. If we click ‘Print layout’ button in menu we come to ‘page view’ where we can change nothing in report and see exactly what will be printed. This mode doesn’t use memory so much, so we can use this view easier. Few additional points here: a) all report initially open in interactive mode so users need manually change mode; Mode is not available if report is not allowed to preview like Sales Invoice or Order Confirmation.
   
2. Report run SAVEASPDF works better if we call it directly without request form. However then users need to do more actions to open report. But maybe this can be reasonable in some cases.
3. And finally if there are requirements to run big reports with many pages (100 and more) then better is to run them on server side, just because server is 64 bits and usually has more available RAM. This can be done by creating codeunit which runs report SAVEASPDF. Then add codeunit to job queue. Job queue executes codeunit and create pdf file.

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Gedas Busniauskas
Microsoft Lithuania
Microsoft Customer Service and Support (CSS) EMEA





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