cygwin + rsync issue under Windows 7 x64
jamie at shareable.org
Sun Mar 7 22:19:51 MST 2010
Wayne Davison wrote:
> I'd imagine that both ssh and rsync start using a lot of CPU because
> the socketpair must be indicating that it is ready for a write (or
> read) but the actual write() (or read()) fails to return any bytes (as
> long as errno is something like EAGAIN, EINTR, or EWOULDBLOCK, rsync
> will try again). Â If you want to test that theory, you could add some
> prints to rsync's io.c file near the 3 uses of EWOULDBLOCK and have it
> output what errno it gets. Â If you get that fixed, the programs that
> interface with a socketpair should go back to normal.
It would not be the first time Cygwin did something like that.
11.5 years ago, Cygwin32 b19.1, I found it returning EAGAIN
continuously when reading from pipes to a child process and from the
master side of a pty to a child process, while select() indicated
"ready for exception" (at least from the pty master; I don't remember
if it was that or "ready for read" from a pipe).
How interesting that sockpair() now looks like having a similar problem.
Perhaps the sockpair problem might be related to the getting stuck
people occasionally report with rsync + ssh + Cygwin ? I.e. maybe
disabling socketpair() will fix the stuck problem too?
Maybe the next time someone encounters it, they'll google this thread,
try it and let us know how it went, thanks :)
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