Very slow Cygwin startup on Windows 7

Dennis Hagarty (dehagart)
Thu Feb 12 06:05:00 GMT 2015

Thanks Andrey,

I'll do that.

I see the purpose of the update - just the way it was documented didn't really make 
it clear to me that it was going to hit my DC and cause performance issues.

The UID stuff doesn't really worry me too much, I was happy with the old way.
But I'll use your suggestion tomorrow.


-----Original Message-----
From: Andrey Repin [] 
Sent: Tuesday, 10 February 2015 01:05
To: Dennis Hagarty (dehagart);
Subject: Re: Very slow Cygwin startup on Windows 7

Greetings, Dennis Hagarty (dehagart)!

>>> Well, nsswitch.conf was a good suggestion - I'd left it as the default
>>> (which is empty), but I added a 'files' entry and it came good again.
>>> Changing the passwd and group entries to 'files db' makes it very slow
>>> again.
>>Limit the number of entries that Cygwin fetches from the DC.  Also,
>>starting a cygserver would help.
>>> Not sure what changed here, I have a very good connection to my DC,
>>> but obviously something wrong here now.
>>You may be surprised at how slow a DC really can be when it sees some
>>load, regardless of connection speed when you try to fetch several
>>thousand entries.  If I were to try a 'mkpasswd -d' on our DC I'd
>>usually have to wait about an hour with very little network traffic to
>>show (the resulting file would be about 4MiB).

> Thanks Achim - I've recreated my passwd and group files to be sure.
> I checked some domain lookups and they take a second or two for each entry - quite slow.

> So, I'll leave nsswitch where it is for now and I've started cygserver.

If you are accepting suggestions, and up for some experimentation, try this:

# getent passwd $(id -u) > /etc/passwd
# getent group $(id -G) > /etc/group
# echo -e "#\npasswd: files db\ngroup: files db\n" > /etc/nsswitch.conf

and start bash without cygserver running. Just for test.
The idea is to have "your" groups in files so that in simple case of (just
startup" Cygwin don't have to talk to DC all too much. If at all.

You'd still need to run cygserver to benefit from long-time caching, though.

> But I'm just wondering how this failed after I updated - I was using it
> successfully 30 mins previously.
> I've had it configured this way for years.

That was the sole point of the update. :) No, no. Not the snail's speed, ofc.
But the more direct connection of Cygwin to the native security environment.
File ACL's included.

Andrey Repin ( 10.02.2015, <02:54>

Sorry for my terrible english...

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