Running MiKTeX commands in parallel fails

[Sharken03]

Checklist:

• I am reporting a bug others will be able to reproduce
• I have installed the latest MiKTeX updates
• I have checked the MiKTeX log files

Step-by-step reproduction instructions
On a Windows machine do the following:
Create a minimal temp.tex file.
Install DbgView and start DbgView.
Set trace flags like this: setx MIKTEX_TRACE "access,core,mmap"
Run texify.exe:
texify.exe --batch --pdf --tex-option=-halt-on-error temp.tex

DbgView will now show something like this:

Running multiple instances of Texify.exe will eventually lead to an access denied error like this:
Errorlog.txt

The root cause seem to be that MiKTeX by default writes to a common file, and having more than one instance of Texify.exe doing this will lead to an error.

A workaround is to mark the Data folder as read-only, which the code in winMemoryMappedFile.cpp will respect.
It would be a lot better if the design was changed, so that multiple instances of MiKTeX commands can be run.

[edocevoli]

I think this is has been fixed with one the latest updates.