在线程之间共享类的实例

如何解决在线程之间共享类的实例

这是VB.net中多线程（使用BackgroundWorker）的简单示例，其类（ClassJobs）已在主（UI）线程中初始化。

Public Class frmMain

    Dim pClassJobs as New ClassJobs
    Dim bwSecondaryThread As New System.ComponentModel.BackgroundWorker

    Private Sub frmMain_Load(sender As Object,e As EventArgs) Handles MyBase.Load

        AddHandler bwSecondaryThread.DoWork,AddressOf bwSecondaryThread_DoWork
    End Sub

    Private Sub ButtonPrimaryJob_Click(sender As Object,e As EventArgs) Handles ButtonPrimaryJob.Click
        
        'Here the main (UI) thread call a sub from pClassJobs
        Call pClassJobs.Job_A()

        'Then the main thread launch the BackgroundWorker
        Call bwSecondaryJobs.RunWorkerAsync()

    End Sub

    Private SUb bwSecondaryThread_DoWork
        
        'Here the BackgroundWorker call a sub from pClassJobs
        call pClassJobs.Job_B()
    End Sub
End Class

问题：：此处实例pClassJobs已在Main线程中初始化，但在BackgroundWorker中被调用。那么工作在哪里执行？
在已初始化pClassJobs的主线程中还是在已调用pClassJobs的BackgroundWorker线程中？