[ruby-core:31220] [Bug #3523] win32 exception c0000029 on exit using fibers

Issue #3523 has been updated by B Kelly.


Hi,

Yusuke Endoh wrote:
> 
> What's going on?
> 
> Indeed, this looks like core's bug.  But we can't do anything unless
> there is reproducible code.  Meanwhile, I set the priority to Low.
> If you could create code that you can disclose, please reply to this
> thread.

Sorry for the delay.

Last week I made several attempts to create smaller sample 
programs which reproduced the error.  To my surprise, the
smaller programs fail to produce the error, but the larger
program still gets the error EVERY time.

Here is what I have learned so far:

1. The 0xc0000029 exception apparently means:
"An invalid unwind target was encountered during an unwind
operation."

2. I suspect the error may have something to do with having
a C++ stack frame when switching fibers.  I am using 
EventMachine, and changing fibers on the event callback.

Example:

  EM-fiber: callback into ruby (with C++ stack frame)
    transfer to Dispatch-fiber
    transfer back to EM-fiber
  return

But again, I can't reproduce the error with a program
as simple as the above.

3. I have back-ported the "cont.c" from trunk to 1.9.2, and
the 0xc0000029 problem disappears.

4. Apparently cont.c from trunk uses FIBER_USE_NATIVE, which
was briefly in 1.9.2, but was reverted.

That is all I know, so far.

By the way, I was interested to learn the reason why
FIBER_USE_NATIVE was reverted in 1.9.2.  I think the
following discussion may contain the answer, but, 
Google Translate was not very helpful:

http://redmine.ruby-lang.org/issues/show/3295

If possible, could anyone who understands Japanese
please summarize the reason for the revert in 
English?


Meanwhile, I will make another attempt to reduce
the amount of code needed to reproduce the problem,
in the next couple days.


Thanks,

Bill



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