16.7ms in the life : Tools

DVB Guide issues - "cannot schedule recoding because guide data cannot be accessed"

Peter Rosser — Thu, 16 Feb 2006 10:27:00 GMT

We have been getting reports about Guide problems from DVB users across Europe and the world, hopefully in time for the next Rollup release (external date not yet announced, but should be late Q1 to early Q2). The problem typically manifests itself when scheduling many shows to record, but can occur anytime. Without a code fix, you cannot work around the issue cleanly/easily, but closing the shell (Media Center UI) and restarting the "Media Center Scheduler Service" (ehsched) will reset the state of the machine.

Edit: This is the "cannot schedule recording because guide data can't be accessed" issue.

We root-caused the problem to an unusual memory management problem in how we deal with the Guide data. For performance reasons, we temporarily increase certain buffer sizes during a Guide download, and decrease them again later. There is a timing issue with garbage collection events in some situations, though, that can cause the decrease to not take effect "in time", thus keeping the buffer sizes large. This does not actually reduce the amount of real memory used, but it does exhaust the virtual address space eventually. You can observe the behavior using SysInternals' Process Explorer by adding the "Virtual Size" column (under the Process Performance tab) and observing its value for ehrec.exe.

With better knowledge of the cause, though, comes a better workaround than "gun ehshell.exe and restart ehsched when it happens". Until the fix comes out, the best thing to do to prevent this problem from occurring is probably to set up a Scheduled Task to do those things for you at a predictable time. To wit:

Download recycle_mce.cmd from here. (script to recycle ehshell.exe and TV services). Unpack the script somewhere on your drive.
Change your Guide download time to a time that you are not likely to have a need to either watch TV on your MCE or record a show. 4am is pretty safe for me, but to each his own. I wrote a tool that lets you edit this time easily, you can download it from my site.
Create a Scheduled Task to run the script daily about 30 minutes after the time you configured the Guide to download. If you have a modem, you may need to give it more time. If you have a pretty fast computer and broadband, 30 minutes is very generous. Guide to creating scheduled tasks.

It's not a perfect solution, since a) it presumes you have a time during the day you will not make recordings or watch TV, and b) it cannot prevent the problem 100%, especially if you are a "heavy" user. If you run into the problem, though, running recycle_mce.cmd will at least reset your state.

The real fix is coming with the next rollup, but since there are users out there feeling pain now, I thought I'd try to help a little.

The programs, scripts, and instructions in this posting are provided AS-IS, with no warranties, and are not sanctioned nor released by Microsoft.

Visual Studio 2005 Shipping on my Birthday

Peter Rosser — Tue, 01 Nov 2005 08:14:00 GMT

You know I'm a geek when something like that gives me even a little bit of a thrill. November 7th... not just an election day or my birthday, but also the VS2005 public ship day. ^_^. I'm installing it now on my primary and backup dev boxes at work now... sometimes the perks of working here are pretty nice. Mmm... generics.

One of my coworkers suggested I take another look at Managed C++ (during our conversation I expressed my "dismay" at the prior version's foibles), so I'll take a peek at that as soon as I have a spare cycle or two. It's pretty hard to get any free time with the painting at home and the heavy influx of QFE issues we always get post release, but I'm sure I'll manage.

MceRepair 0.2

Peter Rosser — Sat, 22 Oct 2005 08:20:00 GMT

I've posted an update to MceRepair at http://www.pegasi.com/MceRepair_0.2.zip, which adds additional error logging in case of problems. If you tried 0.1 and it failed, 0.2 may work for you. If not, at least you will have more complete information with which I can debug it. [;)]

MceRepair 0.1 (alpha)

Peter Rosser — Thu, 20 Oct 2005 10:51:00 GMT

Having gotten a little fed up with manually re-registering MCE files when MedCtrRO.exe fails, I have created a new command-line utility to automate the task.

MceRepair.exe will:

Repair the ACLs to get COM+ Services working again (see KB909444)
Repair the registration for .NET Framework v1.1 libraries (should fix the "Entry Point Not Found in mscoree.dll" error during registration).
Reinstalls all MCE Windows Services
Re-registers COM components of MCE
Reinstalls managed assemblies into the GAC
Recreates native images for managed assemblies (ngen)

Of course, I can't warranty any of this stuff, but if you find it useful, feel free to use it. If you run this and still cannot get things working on your machine, please let me know! Please include your %windir%\MedCtrOC.log file, %windir%\ehome\ehshell.crash (if it exists), and if you're experiencing EPG problems, a zipped/RARed copy of your %ALLUSERSPROFILE%\Application Data\Microsoft\eHome\EPG folder.

MceRepair 0.1 (alpha) is posted at http://www.pegasi.com/MceRepair_0.1.zip [obsolete, use 0.2 below]

EDIT: A newer version, 0.2, is now available at http://www.pegasi.com/MceRepair_0.2.zip