Re: [gold][patch] Reduce heap usage for string merge sections

[Ian Lance Taylor <iant at google dot com>]

Cary Coutant <ccoutant@google.com> writes:

>>> Good idea -- do you have a suggestion for estimating that? I could
>>> just divide the size of the section by a presumed average string
>>> length. The average string length might depend heavily on the source
>>> language and what the section is, though. (Although I suppose a
>>> conservative estimate, based on a large average string length, is
>>> better than doing nothing.)
>>
>> The cost of overestimating is not that high, so I would just assume that
>> each string has, say, 8 characters.
>
> It turns out that the cost is actually quite substantial. For
> .debug_str, if the average string is, say 64 bytes, an estimate based
> on an average of 8 would reserve 8 times as much memory as we actually
> need. On my benchmark, adding the reserve call made gold use about 3
> times as much memory for the Merged_string structures.
>
> Instead of using a fixed average string size, I could sample the first
> N bytes of the section to come up with the estimate. How does that
> sound?

Hmmm, clearly my intuition here is wrong.  I'm not sure what is best.

Ian