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Re: [Help-bash] make function local


From: Chet Ramey
Subject: Re: [Help-bash] make function local
Date: Thu, 16 Apr 2015 11:07:34 -0400
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:31.0) Gecko/20100101 Thunderbird/31.6.0

On 4/12/15 5:56 PM, Eduardo A. Bustamante López wrote:
> Oh, you already have lots of things to do to bother with this :-)
> 
> Anyways, I'll expand them.
> 
> On Fri, Apr 10, 2015 at 04:35:25PM -0400, Chet Ramey wrote:
>> On 4/10/15 10:13 AM, Eduardo A. Bustamante López wrote:
>>
>>> - a faster implementation of the variable lookup code
>>
>> What does this mean, exactly?  Optimizing the existing code paths? (Have at
>> it.)  Different semantics?  Static as opposed to dynamic scoping?
> 
> Yes. I've been using gprof to study the code paths of some basic functions, 
> and
> it seems like it spends quite some time in the find_variable() and related
> functions (IIRC, there was an mt_hash or something function taking up some
> precious time). 

I knew that rang a bell somewhere.  mt_hash is a function in the bash
malloc library that keeps track of all allocations and deallocations in
a table.  It's part of the debugging that is enabled when you build from
the devel code.  It's been well-known for a long time that the debugging
code in malloc slows bash down considerably; that's why it's not enabled
as part of bash releases.


-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    address@hidden    http://cnswww.cns.cwru.edu/~chet/



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