More details about the tmux 2.0 regression

Corinna Vinschen corinna-cygwin@cygwin.com
Mon Jun 8 12:42:00 GMT 2015


On Jun  6 12:58, İsmail Dönmez wrote:
> Hi,
> 
> I had a nice discussion with tmux maintainers over at
> https://github.com/tmux/tmux/issues/13 about the tmux 2.0 regression
> on Cygwin.
> 
> Long story short, tmux is trying to read /proc/<pid>/cmdline and
> /proc/<pid>/cwd for various reasons and for non-Cygwin programs this
> is quite slow. You can reproduce this easily run cmd.exe inside bash
> and try to
> 
> cat /proc/<pid of cmd.exe>/cmdline

Good catch!

The problem here was that this functionality is very Cygwin centric.  It
tries to call into the process itself to fetch the information.

E.g, assuming you have some /proc/1234, it tries to fetch the information
by sending a request to process 1234 and then waits for that process
setting a semaphore.  A non-Cygwin process will obviously fail to do so,
not knowing about the method at all.

I fixed that in the Cygwin git repo and it seems to work much better now
to run native tools inside tmux with this change.

I'll upload a developer snapshot on https://cygwin.com/snapshots/ later
today.


Thanks,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat
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