How do I attach a second process when the debugger starts?

Question

I'm trying to attach to a second process when the debugger starts using the code:

DTE dte = BuildaPackage.VS_DTE;

EnvDTE.Process localServiceEngineProcess = dte.Debugger.LocalProcesses
    .Cast<EnvDTE.Process>()
    .FirstOrDefault(process => process.Name.Contains("ServiceMonitor"));

if (localServiceEngineProcess != null) {
    localServiceEngineProcess.Attach();
}

It works fine when the debugger is not running, but when trying to attach when trying to attach during the VS_DTE.Events.DebuggerEvents.OnEnterRunMode event, I get the error:

A macro called a debugger action which is not allowed while responding to an event or while being run because a breakpoint was hit.

How do I attach to another process right when the debugger starts?

Answer 1

I did find an answer to this, it's a hacky solution methinks, but if someone comes along with a better answer I'd love to hear it. In essence you attach the debugger before the debugger actually starts running. Consider:

internal class DebugEventMonitor {

    // DTE Events are strange in that if you don't hold a class-level reference
    // The event handles get silently garbage collected. Cool!
    private DTEEvents dteEvents;

    public DebugEventMonitor() {
        // Capture the DTEEvents object, then monitor when the 'Mode' Changes.
        dteEvents = DTE.Events.DTEEvents;                     
        this.dteEvents.ModeChanged += dteEvents_ModeChanged;
    }

    void dteEvents_ModeChanged(vsIDEMode LastMode) {
        // Attach to the process when the mode changes (but before the debugger starts).
        if (IntegrationPackage.VS_DTE.DTE.Mode == vsIDEMode.vsIDEModeDebug) {
            AttachToServiceEngineCommand.Attach();
        }
    }

}