Re: Find working improperly causes updatedb to take forever

[Eric Blake <ebb9 at byu dot net>]

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According to Victor E. Vaile, IV on 7/11/2006 8:39 PM:
> Hello,
> 
> 	I upgraded my cygwin today from 1.5.19-4 to 1.5.20-1 (along with other various packages to their current versions).  I ran updatedb, and
> instead of it taking less than a few minutes, the prompt hadn't returned after several minutes.  I fired up procexp.exe (from
> sysinternals.com) and saw that the find.exe process was opening several registry keys in HKCR.  This process was taking between 20-45% of my
> cpu as well.  I did a quick test of the following command:
> 
> /usr/bin/find / \( -fstype proc \) -prune -o -print0

As written, the \( \) are unnecessary in your example.

The reason that this doesn't work is that cygwin's filesystem name
reporting is not very good.  Try 'find / -maxdepth 1 -printf '%f:%F ' to
see what I mean.  /proc is listed as "unknown", not "proc", as its fstype,
so your above attempt was failing to prune /proc (and hence, that explains
why you were traversing /proc/registry).

As to why it is different now that you upgraded cygwin: a patch was added
that allows readdir() to return virtual directories from within the root
directory, where previously it did not.  And /proc is a virtual directory.
 So the behavior, while not necessarily nice, is expected; and serves to
illustrate the need to be careful with find when crossing file system
boundaries.  Try -xdev, instead of -fstype ... -prune.

> 	As far as I know the syntax for the find command should work as above.

Only if cygwin were to be patched to actually provide find with the
information it needs to see /proc is -fstype "proc" rather than "unknown".
 cygwin.com/acronyms#PTC.

However, if updatedb is trying this, maybe I should look into patching that.

- --
Life is short - so eat dessert first!

Eric Blake             ebb9@byu.net
volunteer cygwin findutils maintainer
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