Re: [Boost-users] More than strange performance test results of Boost.MultiIndex

Subject: Re: [Boost-users] More than strange performance test results of Boost.MultiIndex
From: Ernest Zaslavsky (ernest.zaslavsky_at_[hidden])
Date: 2014-11-19 00:08:24

Do you dare to suspect me to be running against debug build!? :) just kidding.
And surprise, surprise. I've found the problem. One thing I've forgot to mention and no one asked for it, It was boost version I'm using - 1.52. Don't know if it is a known bug in this version, but once I've switched to 1.57 everything started to work as expected. So, I rest my case.

-----Original Message-----
From: Boost-users [mailto:boost-users-bounces_at_[hidden]] On Behalf Of Lars Viklund
Sent: Tuesday, November 18, 2014 4:19 PM
To: boost-users_at_[hidden]
Subject: Re: [Boost-users] More than strange performance test results of Boost.MultiIndex

On Tue, Nov 18, 2014 at 07:31:47AM +0000, Ernest Zaslavsky wrote:
> I was rewriting our production code since there were performance 
> concerns and switched from our monstrous std::map to boost 
> multi_index_containers which looked exactly what we need. Then when 
> running performance tests I've noticed that once I use composite_key 
> which includes string the performance drops in orders of magnitude, to 
> be precise, 5 orders. Which, I would say, not reasonable at all. So I 
> created a minimal repro case to post here and ran it on Coliru.
> Surprise! This behavior does not reproduce on GCC, moreover, the 
> composite key with string for some reason was searched twice faster 
> than int only composite. To me it sounds like a bug or in 
> Boost.MultiIndex MS specific implementation (if such exists) or in 
> MSVC.

I wonder if GCC's stdlib still insists on using their abominable Copy-on-Write string implementation.

In any way, ensure that your tests on Windows are against a release runtime and without the horrible heap you get when launching from a debugger (_NO_DEBUG_HEAP=1 environment variable to mitigate that). 

> Tech details: VS2012, Win7x64. The code was compiled and linked targeting x64 architecture.
> Test output on my local machine:
> Populating data.
> Index size: 999999
> Running FlyweightMICTest::deepTest
> 
> Checking getTestData perf.
> 999999 sum of all IDs.
> 1M calls took 0 seconds or 125ns per call.
> 
> -------------------------------------------------------------
> Populating data.
> Index size: 999999
> Running FlyweightMICTestWithString::deepTest
> 
> Checking getTestData perf.
> 99 sum of all IDs.
> 99 calls took 1 seconds or 10132326ns per call.
> 
> ===============================================================
> 
> Coliru output (live example can be found here http://coliru.stacked-crooked.com/a/ef76d297279f15a8):
> Populating data.
> Index size: 999999
> Running deepTest
> 
> Checking getTestData perf.
> 999999 sum of all IDs.
> 1M calls took 0 seconds or 395ns per call.
> 
> -------------------------------------------------------------
> Populating data.
> Index size: 999999
> Running deepTest
> 
> Checking getTestData perf.
> 999999 sum of all IDs.
> 999999 calls took 0 seconds or 181ns per call.

--
Lars Viklund | zao_at_[hidden]
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