Memory leak in Observable.Generate results in StackOverflowException or OutOfMemoryException

[Dorus]

Observable.Generate leaks a SerialDisposable every iteration. For example:

        var scheduler = Scheduler.Default;
        Observable.Generate<int, int>(
            0
            , i => i < 12000
            , i => i + 1
            , i => i
            , i => scheduler.Now,
            scheduler).Subscribe();

Gives a StackOverflowException instantly. Notice I use scheduler.Now to speed up the problem, using any timespan below 1 ms works, as at that span, Observable.Generate goes to the next iteration instantly. If you use a timespan at or above 1ms, it switches to 10-15ms delays (the precision of Windows timers).

Another example:

        var scheduler = TaskPoolScheduler.Default;
        var theDelay = TimeSpan.FromTicks(1);
        Observable.Generate<Tuple<int, DateTimeOffset>, int>(
            Tuple.Create(0, scheduler.Now),
            _ => _.Item1 < 20000000,
            tup => Tuple.Create(tup.Item1 + 1, tup.Item2.Add(theDelay)),
            tup => tup.Item1,
            tup => tup.Item2,
            scheduler)
            .Subscribe();

Gives a out of memory exception after 8 seconds. If you increase the delay to 1-15ms, i estimate it will run out of memory at after 80-800 hours, however did not have time yet to leave it running for a month, the memory profiler still shows leaked objects.

[baltie]

I can confirm that this is a problem. I just tracked down a memory leak in our application to Observable.Generate(), seems to be the exact same issue as reported here.

[raffaeler]

+1 I had the same problem with Generate and timer below 1ms.
It generates a chain of disposable[] which points to the previous one creating a concatenation so long that both VS2015 debugger and windbg + sos crash if the dump is moderately long.

[danielcweber]

@Dorus @baltie @raffaeler Can you confirm this is still a problem with the current preview of Rx 4.0? I can't reproduce it any more.

[akarnokd]

On Windows with preview3, net45, console app, the code above works for me with all the standard scheduler types offered by Scheduler.

[akarnokd]

Should be fixed in #1067.
Related: #1065