X11 forwarding extremely slow (unusable) after Cygwin upgrade (starting from cygwin1.dll version 3.1.0-0.4)

Takashi Yano takashi.yano@nifty.ne.jp
Mon Jan 6 14:40:00 GMT 2020


On Sat, 4 Jan 2020 10:51:42 +0900
Takashi Yano wrote:
> On Thu, 2 Jan 2020 22:16:02 +0000
> Ken Brown wrote:
> > I think this narrows it down to one of the following commits:
> 
> I looked into this probelm and found the issue occurs after
> the following commit.
> 
> > commit 915fcd0ae8d83546ce135131cd25bf6795d97966
> > Author: Takashi Yano <takashi.yano@nifty.ne.jp>
> > Date:   Thu Sep 5 13:22:54 2019 +0900
> > 
> >      Cygwin: pty: Fix select() with pseudo console support.
> 
> I investigated this deeper, and found:
> 
> 1) xterm in ssh -Y session calls select() about 1000 times
>    at startup.
> 2) pi->thread->detach() in pty_slave_cleanup() takes about
>    20usec in usual, however, it takes more than 10msec
>    in ssh -Y session.
> 
> As a result, start up of xterm takes more than 10 sec.
> 
> I have no idea so far why cygthread::detach() becomes
> so slow in ssh -Y session. :-(

I have just posted a patch for this issue.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>

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