Bug 647972 - augtool uses 100% CPU when you hit tab key
augtool uses 100% CPU when you hit tab key
Product: Fedora
Classification: Fedora
Component: augeas (Show other bugs)
Unspecified Unspecified
low Severity medium
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Assigned To: David Lutterkort
Fedora Extras Quality Assurance
Depends On:
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Reported: 2010-10-30 03:14 EDT by Richard W.M. Jones
Modified: 2013-04-30 19:42 EDT (History)
4 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2012-08-16 15:00:21 EDT
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oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
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Description Richard W.M. Jones 2010-10-30 03:14:02 EDT
Description of problem:

augtool uses 100% CPU for about 30 seconds when you hit
the tab key at a certain point.

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1. As root, run augtool
2. Type:  ls //fi
3. Hit the <tab> key.
Actual results:

augtool spins using 100% CPU for about 30 seconds.  Also
augtool is unresponsive during this time.

Expected results:

Should tab-complete the path or otherwise remain

Additional info:
Comment 1 David Lutterkort 2011-01-12 15:29:54 EST
The problem is that hitting <TAB> there causes aug_match("//*",...) to be run to get possible completions.

Unfortunately, that path expression is extremely expensive to evaluate, and process for completion, since it matches every node in the tree, anywhere in the tree. And the autocompletion code needs to go through and check if the label starts with 'fi'.

Not sure how to fix this .. maybe not allow auto-completion of path expressions with '//' in them ? Or w
Comment 2 Richard W.M. Jones 2011-01-12 15:45:50 EST
I wonder if it's possible to estimate the cost of an expression
before evaluating it, and perhaps (in autocomplete) give up or
print a message.

I think I was confused when I filed the BZ, thinking that all
Augeas paths start with double // which of course they don't.
Comment 3 Fedora End Of Life 2012-08-16 15:00:24 EDT
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