Trouble Shooting Bulletin 4

Transcription

1 Trouble Shooting Bulletin 4 Microsoft Presentation Font Cache & Excessive CPU Usage June 21, 2012

2 T r o u b l e S h o o t i n g B u l l e t i n 4 P a g e 1 Change Log Version Date Description of Changes 1.0 June 21, 2012 First version sent and uploaded to training area of website

3 T r o u b l e S h o o t i n g B u l l e t i n 4 P a g e 2 The Problem On some older systems typically running Windows XP/Vista we ve had some reports of CPU use being excessively high and of some NavSim software windows not opening. In NavSim software, the affected windows tend to be the Device Manager and some sub-windows such as Recording Options. Some have noted that the program itself stops responding and one of the CPU cores stays at 80+%. This problem seems to be with the Windows Presentation Font Cache which is part of the Windows Presentation Foundation (WPF) feature. This problem is not unique to NavSim. In fact, a number of Windows users have experienced similar issues and have made reports about it to Microsoft: Error message when you run a Windows Presentation Foundation (WPF)-based application in the.net Framework 3.0: presentationhost.exe running at 50% CPU: US/wpf/thread/7cc032c1-5f4d-4518-adc6-f53afd051e6b The Solution In order to perform the following steps, you have to be an Administrator of your local machine. If you are not a local admin of your system, and you have purchased a complete PPU system from NavSim, contact us and we can arrange a time to remotely login to your machine to make the below changes to Windows for you. Reset the presentation font cache: 1. Start > Control Panel > Administrative Tools > Services (or type "services.msc" from the run command box). 2. Stop the "Windows Presentation Foundation Font Cache " service. 3. Delete the cache file: "FontCache dat" found in: WinXP: "C:\Documents and Settings\LocalService\Local Settings\Application Data" Vista/Win7: "C:\Windows\ServiceProfiles\LocalService\AppData\Local" 4. Restart the service or the machine if needed.

4 Detailed Information T r o u b l e S h o o t i n g B u l l e t i n 4 P a g e 3 We ve included some extra detail on this issue from the Tune Up blog originally found here. Your PC worked perfectly fine the other day, but suddenly, it s acting up. Performance went down, CPU activity increased, and your laptop s or desktop s fan is going wild there s clearly some resource hog affecting your system. If tuning tips didn t resolve your situation, you might want to look at Windows Task Manager (hit CTRL+SHIFT+ESC at the same time). Over the past few months, I ve heard that PresentationFontCache.exe is known to run amok and consume 50% of your processor s resources. And, it actually seems to be a rather common problem. If this is happening on your system, we have the right fixes for you! PresentationFontCache.exe is running constantly at 50% CPU usage it's time to put a stop to this What is Presentation Font Cache? The Presentation Font Cache is part of the Windows Presentation Foundation (WPF) feature, which allows programmers to develop graphically richer applications. It is a part of the.net Framework (3.0, 3.5, 3.5 SP1 and 4.0), which, in turn, is part of Windows Vista (3.0) and Windows 7 (3.5). Some of your installed applications may require WPF and make use of the Presentation Font Cache. This service loads font glyph information into memory and helps share these fonts with all of the installed WPF applications. As such, applications that use the WPF framework start a bit quicker, and font pickers (such as this one) might see a slight performance increase.

5 T r o u b l e S h o o t i n g B u l l e t i n 4 P a g e 4 By default, this service is set to manual, so it won t launch automatically and cause performance improvements (in non-wpf applications) or any problems. However, once you use a WPF program, this service will start and in some cases set to start automatically when Windows launches! Why is it burning my CPU? The Presentation Font Cache loads all fonts into its font cache (which is stored on your hard disk, but more on that later). However, at some point, this cache may become corrupted and unreadable due to a specific font. Then, the Presentation Font Cache will start to become unresponsive and get caught in a I try to launch, but I m stuck, so I will try it again loop. That s what causes the incredibly high CPU usage, and what may even result in a sudden shutdown due to overheating. Luckily, there are a few solutions to this problem! Solution #1: Delete the font cache file The font cache is located under the following folder: %windir%\serviceprofiles\localservice\appdata\local. Simply hold down the WIN key on your keyboard and press R. Then, enter the path above and click OK. Delete all the FontCache dat files you find, such as FontCache-System.dat or FontCache dat.

6 T r o u b l e S h o o t i n g B u l l e t i n 4 P a g e 5 This will cause the WPF font cache to rebuild itself. However, if the problem persists, you might need to shut down the WPF font cache permanently. Solution #2: Shutting down the WPF font cache If all else fails, you have no choice but to disable the font cache. This may cause a slight slowdown when loading applications that heavily rely on fonts or offer a font picker (which loads hundreds or even thousands of your installed fonts). But, it s a lot less painful then working under 50% CPU stress and hearing a fan working on overdrive. So how do you get rid of WPF font cache? It s simple go to Control Panel, and click on System and Security, Administrative Tools and Services. Scroll all of the way down until you see Windows Presentation Foundation Font Cache. Double-click on this entry, and select Disabled from the Startup type list. That s it! Click on OK, and reboot your system. You may encounter some slight delays in your WPF applications, but at least your PC will be running at full speed again.