Anyone have experience with this? And...is there any way to suppress this behavior, so that public variables are not shared between threads? Although it seems that could be really useful, I'm working with a large legacy app strewn with public variables that must retain their values in their own threads (and I'd really don't want to rewrite it to change the publics to properties).

Are you using the vfpt.dll runtimes? They should not share global vars although some VFP system vars are in fact shared.

+++ Rick ---

The registry entry has the setting Foxruntime = VFP9T.DLL, so I assume yes.

Here's my code. In the real-life scenario test1 is the legacy app and test2 is an olepublic adapter dll.

Test1

return createobject("test1")

define class test1 as Custom

	inCounter = 0
	
	function AddToCounter
		lparameters tnNum
		this.inCounter = this.inCounter + tnNum
	endfunc
	
enddefine

Test2
Compiled as SingleUse or MultiUse yields the same results.
Compiled a Multi-Threaded COM Server (dll)
When run, Test2.inCounter is within each thread (counts to 10) and goTest1.inCounter is shared (counts to 20).
The commented code has test1 as a property of test2 instead of a global variable, and counts to 10 instead of 20.

define class test2 as Session olepublic

	inCounter = 0
	* ioTest1 = null
	
	function init() as Boolean
		public goTest1
		goTest1 = test1()
		* this.ioTest1 = test1()
	endfunc
	
	function AddToCounter(tnNum as Integer) as String
		local lcReturn
		this.inCounter = this.inCounter + tnNum
		goTest1.AddToCounter(tnNum)
		lcReturn = transform(goTest1.inCounter) + "," + transform(this.inCounter)
		* this.ioTest1.AddToCounter(tnNum)
		* lcReturn = transform(this.ioTest1.inCounter) + "," + transform(this.inCounter)
		return lcReturn
	endfunc

enddefine

.NET Test App
I used tblimp to create the .Net wrapper: tlbimp test2.dll /out:Test2RCW.dll

using System;
using System.Collections.Generic;
using System.Threading;
using Test2RCW;

namespace tester
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(String.Format("Main: Threading Model = {0}", Thread.CurrentThread.GetApartmentState()));

            // Run outside static main
            Program p = new Program();
            p.Tester();

            Console.WriteLine("Press [ENTER] to exit...");
            Console.ReadLine();
        }

        public void Tester()
        {
            Console.WriteLine(String.Format("Tester: Threading Model = {0}", Thread.CurrentThread.GetApartmentState()));

            Thread t1 = new Thread(Worker);
            Thread t2 = new Thread(Worker);

            t1.Name = "1";
            t2.Name = "2";

            t1.Start();
            t2.Start();
        }

        public void Worker()
        {
            Console.WriteLine(String.Format("Thread {0}: Instantiate Test2 - Threading Model = {1}",
                Thread.CurrentThread.Name, Thread.CurrentThread.GetApartmentState()));

            var test2 = new Test2RCW.test2();

            Console.WriteLine(String.Format("Thread {0}: Beginning Loop", Thread.CurrentThread.Name));
            for (var i = 0; i < 10; i++)
            {
                var result = ParseNums(test2.AddToCounter(1));
                Console.WriteLine(String.Format("Thread {0}: Test1.inCounter = {1}, Test2.inCoutnter = {2}",
                    Thread.CurrentThread.Name, result[0], result[1]));
                Thread.Sleep(50);
            }
        }

        public List<int> ParseNums(string counters)
        {
            var cnums = counters.Split(new char[] { ',' });

            var result = new List<int>();
            for (var i = 0; i < 2; i++)
            {
                result.Add(int.Parse(cnums[i]));
            }
            return result;
        }
    }
}