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Date: Thu, 27 Apr 2006 05:35:17 -0400
From: "Brett Serkez" <bserkez@gmail.com>
To: cygwin@cygwin.com
Subject: Re: rsync over ssh hang issue understood
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Corinna,

<snip>
> <rant> The "rsync hangs" problem is not actually a new one.  We had
> these reports already ages ago.  However, *nobody* so far having that
> problem seem to be willing to actually debug this problem and track it
> down.  Grrr.  </rant>

This is exactly fair, several individuals did their best to debug the
issue.  I recall several detailed investigations, including my own,
looking in detail at the rsync protocol.

As I recall, this problem was tracked as far as the local pipe between
ssh and rsync on the Cygwin end.

When rsync is run on Cygwin, it runs ssh (presumably via popen) in a
'subshell' to start its cooperative rsync on the target and then they
both read and write on their standard in and out in a strict protocol.
  On a UNIX/Linux system the local pipe is handled by the Kernel, on
Windows, Cygwin has to handle this "magic".  It is this "magic" that
eventually fails, the hang occurs when both rsync process are waiting
on a read from each other, perhaps a flushing or missed signal????????

This problem was at this point, waiting for someone more experienced
to diagnose the local pipe.

Brett

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