What is VB s multithreading and who has information on this

Single-threaded assembly and element models.

All parts created by Visual Basic use the unit model, regardless of whether the part is single-threaded or multi-threaded. A single-threaded assembly has only one cell, which contains all the objects provided by the assembly.

This means that single-threaded DLLs created in Visual Basic can be safely used with multi-threaded clients. However, performance and security are a contradiction, and this security comes at the expense of performance. Calls from all client threads except the current client thread are waiting to be dispatched, as if they were out-of-process.

See Designing thread-safe DLLs.

Ownership of the thread.

Multithreaded process internals do not have their own threads. As described in "Designing thread-safe DLLs," the threads that define each unit belong to the client.

In contrast, a multithreaded out-of-process component may have a thread pool with a fixed number of threads, or set up a thread for each externally created object.

Design multithreaded out-of-process parts.

You can take advantage of unit mode progression to create multi-threaded process externals. Such widgets provide objects that can run on different execution threads.

To assign objects to threads in out-of-process parts, Visual Basic provides three models. You can select one of the models by setting the No User Interface Execution box on the General tab in the Project Properties dialog box.

The setting for the thread assignment model "no user interface execution".

Single Execution Thread Select the Thread Pool option to specify the number of threads as one.

Thread pool for circular assignment threads Select the Thread Pool option and specify the number of threads available.

Each externally created object has its own thread Select the "Threads per object" option.

A single thread of execution.

When No UI Execution is selected, a single thread of execution is the default. Use this option to compile parts developed in earlier versions of Visual Basic without thinking about threads.

If you use the No User Interface Execution option to recompile the part, the server will no longer be able to display the message box and will not be able to receive administrator intervention. However, such messages can be logged to the Windows NT event log (or a log file of your choice), see Event Logs for Multithreaded Parts.

Looping thread pools.

When a client requests an object, Visual Basic uses the program pool to create the desired object on the next thread. When a thread reaches the end of the thread pool, it starts from the beginning.

Now it's possible to multi-thread.