Re: [Boost-users] the problem about boost trim function in multi-thread

Subject: Re: [Boost-users] the problem about boost trim function in multi-thread
From: Marshall Clow (mclow.lists_at_[hidden])
Date: 2012-06-19 11:02:31

On Jun 19, 2012, at 7:39 AM, Igor R wrote:

>> I use boost trim function and find it perform very well in single-thread
>> environment.
>> 
>> But when I call trim function in multi-thread environment, it will have a
>> poor performance.
> 
> 
> Perhaps, it's because boot::trim() uses std::locale(), which involves
> a lot of locks in a multi-threaded environment. But try analysing it
> with a performance profiler.

That should be really easy to test.
How does your test code perform if you change it to this:

void *TrimNString(void *arg) {

    string base ="fdsffdsafdsa";
    locale loc = locale();
    for(int i = 0; i != 50000000;i++)
    {
        string str = base;
        trim(str, loc);
    }
    return 0;
}

Note also that trim calls the locale to look for whitespace, which is more flexible than your test for " \r\n\t".
That's probably a significant performance difference, too.

-- Marshall

Marshall Clow     Idio Software   <mailto:mclow.lists_at_[hidden]>

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