From: Tim Hunter <TimHunter@...>
Date: 2007-12-11T08:50:15+09:00
Subject: Re: Zero-copy String Handling

Curt Sampson wrote:
> On 2007-12-11 02:44 +0900 (Tue), Robert Klemme wrote:
> 
>> This is what I'd do: create a single string per line and use substring
>> (aka #[]) to create strings that represent the portion needed; byte
>> buffer will be shared then. You don't even need to freeze them because
>> of copy on write.
> 
> This was attractive for a couple of seconds, until I realized that not
> only does it still add a copy of the entire row of data (albeit as one
> large allocation rather than many small ones), but it also doesn't
> reduce my object creation load at all. I seem to recall last time I was
> playing around with this sort of thing and using a profiler, GC was an
> enormous cost for me. This probably isn't surprising given the nature of
> the problem; a typical file might be ten million rows of fifty elements
> each, which would be 500 million object creations and collections.
> 
> cjs

For a problem of this scale, it seems like it would make sense to use a 
custom class that had some of the methods of String - enough for the 
callees to treat it like a String - but not in fact String. Give it a 
.to_s method to convert to a real String when it's really necessary.

-- 
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