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Vb.NET Threads and global variables

I have a globally defined variable (interface?) to my database in ApplicationEvents.vb. (public DB as TransDB)

On startup (MyApplication_Startup) it creates a new instance of the interface, and connects to the database.

then, in the rest of my program i can read/write by using
My.Application.DB.ReadFromDB(<args>)
My.Application.DB.WriteToDB(<args>)
etc.

This works through all my code, except inside a thread.

The thread is for printing and what it does is
1) show a form to allow the user to select the documents to be printed
2) extracts an embedded excel file
3) starts excel and maps data from either a) a form the user has modified, or b) from a saved entry in the database
4) prints the specified documents

inside the thread My.Application.DB is 'Nothing' and the program crashes.

why?  

How can I access this so I don't have to create a 2nd connection?

0
sgaggerj
Asked:
sgaggerj
1 Solution
 
Joel CoehoornDirector of Information TechnologyCommented:
This is very dangerous.  Since the threads may be running simultaneously and be pre-empted at any time, by sharing the same database object between them you are creating the potential for all kinds of race condition and other concurrency issues.  Go ahead and create a 2nd connection in the thread.  Your database can handle it.
0
 
sgaggerjAuthor Commented:
Ahhh.... being new to threads, that's something that didn't even cross my mind.

Thanks!
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