October 2010 - Boost-users - lists.preview.boost.org

Re: [Boost-users] General design question about threading/concurrency
by Julien Martin 26 Oct '10

26 Oct '10

Hello Steve, Thanks for your post. Can you please tell me where to look for information about TBB tuning in the documentation? Julien. 2010/10/25 McKay, Steve F. <Steve.F.McKay(a)ssa.gov> > We have used Intel TBB in a situation similar to yours. We simulate the > U.S. population on 0.1 percent basis (about 300,000 people). We had > attempted to use raw threads before the TBB package became available, but it > was just too hard. The TBB package more or less automatically figures out > how many threads to use, creates the threads, and doles the work out to the > threads, using parallel_for. The biggest hurdle for us was learning how to > create function objects, since that is what parallel_for is set up to use. > But once you get the hang of it, writing your code that way actually helps > you write good code. You may have to do some things differently, or break > things down into smaller steps. > > > > Once you start using TBB, you will find other parts of it that are also > useful, such as parallel_reduce. Also note that, even though TBB is mostly > automatic, you should do some tuning because TBB may not have set the block > size well (how many people, or whatever you are simulating, it allocates to > a thread at one time). It may appear that TBB is not helping to reduce run > time, until you do some tuning. Read the tutorial. > > > > Steve McKay > > Steve.F.McKay(a)ssa.gov > > Social Security Administration > > Baltimore, Maryland 21235 > > > > *From:* boost-users-bounces(a)lists.boost.org [mailto: > boost-users-bounces(a)lists.boost.org] *On Behalf Of *Julien Martin > *Sent:* Monday, October 25, 2010 10:25 AM > *To:* boost-users(a)lists.boost.org > *Subject:* Re: [Boost-users] General design question about > threading/concurrency > > > > Ok. I will try that! > Thank you, > J. > > 2010/10/25 gast128 <gast128(a)hotmail.com> > > Julien Martin <balteo <at> gmail.com> writes: > > > Thanks gast128,I just installed TBB. Can you please tell me what to look > for > (which class, method or concept) in TBB? It is pretty vast...J. > > > 2010/10/25 gast128 <gast128 <at> hotmail.com>If u stay on the same > computer > > (i.e. plain x86 PC with multi cores or multi > > processors), I would recommend Intel's TBB, which splits up tasks > > automatically and tries to keep the processor busy. > > It would be nice if Boost / std C++ would have such a parallellism > library > > because it is an addition to using threads. > > Hello, > > tbb::parallel_for is probably where u will be interested in if the > individual > tasks are truely independent. > > > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users > > >

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General design question about threading/concurrency
by Julien Martin 26 Oct '10

26 Oct '10

Hello, I am writing a program that needs to run N simulations with N >10 000. Obviously, I cannot instantiate N threads at the same time but I cannot run the simulations sequentially either. Can anyone please advise me how to design my program using the boost threading library and concepts please? Thanks in advance, Julien.

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[OT] Permuting graphs
by Cedric Laczny 26 Oct '10

26 Oct '10

Hi, of course, this general topic is off-topic as it is not directly relatod to the Boost Graph Library. And I want to apologize for that in the first place. However, I think that many using the BGL may also have to deal sometimes with such problems. Therefore, I am addressing this question here and hope to find some answers ;) The question is about permuting a graph in order to assess the statistical significance of a certain aspect of the original graph. Sometimes, it is enough to randomly re-wire the existing edges, but other times, more elaborate techniques are necessary. Do you have some literature or references addressing this fact? I am especially interested in topology-conserving permutations (of tripartite graphs). Thank you. Best reagards, Cedric Laczny

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Boost 1.44 compilation on AIX
by jessica.alfonsi＠unipd.it 25 Oct '10

25 Oct '10

Hello, I'm trying to compile without results the Boost 1.44 package embedded with the ALPS libraries (http://alps.comp-phys.org/mediawiki/index.php/Main_Page) on AIX version 6.1, Visual Age C++ compiler 10.1. Soon after launching, compilation stops with the following error messages: subprogram boost::date_time::gregorian_calendar_base<boost::date_time::year_month_day_base<boost::gregorian::greg_year,boost::gregorian::greg_month,boost::gregorian::greg_day>,unsigned int>::end_of_month_day(year_type, month_type) could not be inlined into boost::gregorian::date::date(year_type, month_type, day_type). 1500-029: (W) WARNING: subprogram std::basic_string<char,std::char_traits<char>,std::allocator<char> >::_Assign<std::_Ptrit<char,long,const char *,const char &,char *,char &> >(_Ptrit<char,long,const char *,const char &,char *,char &>, _Ptrit<char,long,const char *,const char &,char *,char &>, input_iterator_tag) could not be inlined into boost::char_separator<char,std::char_traits<char> >::operator() <std::_Ptrit<char,long,const char *,const char &,char *,char &>,std::basic_string<char,std::char_traits<char>,std::allocator<char> > >(_Ptrit<char,long,const char *,const char &,char *,char &> &, _Ptrit<char,long,const char *,const char &,char *,char &>, basic_string<char,std::char_traits<char>,std::allocator<char> > &). 1500-029: (W) WARNING: subprogram std::basic_string<char,std::char_traits<char>,std::allocator<char> >::_Assign<std::_Ptrit<char,long,const char *,const char &,char *,char &> >(_Ptrit<char,long,const char *,const char &,char *,char &>, _Ptrit<char,long,const char *,const char &,char *,char &>, input_iterator_tag) could not be inlined into boost::char_separator<char,std::char_traits<char> >::operator() <std::_Ptrit<char,long,const char *,const char &,char *,char &>,std::basic_string<char,std::char_traits<char>,std::allocator<char> > >(_Ptrit<char,long,const char *,const char &,char *,char &> &, _Ptrit<char,long,const char *,const char &,char *,char &>, basic_string<char,std::char_traits<char>,std::allocator<char> > &). 1500-029: (W) WARNING: subprogram std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >::_Assign<wchar_t *>(wchar_t *, wchar_t *, input_iterator_tag) could not be inlined into boost::detail::lexical_cast<std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >,const wchar_t *,0,wchar_t>(param_type, wchar_t *, size_t). 1500-029: (W) WARNING: subprogram std::basic_string<char,std::char_traits<char>,std::allocator<char> >::_Assign<char *>(char *, char *, input_iterator_tag) could not be inlined into boost::detail::lexical_cast<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,const char *,0,char>(param_type, char *, size_t). 1500-029: (W) WARNING: subprogram boost::filesystem2::basic_directory_entry<boost::filesystem2::basic_path<std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >,boost::filesystem2::wpath_traits> >::replace_filename(const string_type &, file_status, file_status) could not be inlined into boost::filesystem2::basic_directory_iterator<boost::filesystem2::basic_path<std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >,boost::filesystem2::wpath_traits> >::increment(). 1500-029: (W) WARNING: subprogram boost::filesystem2::basic_directory_entry<boost::filesystem2::basic_path<std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >,boost::filesystem2::wpath_traits> >::assign(const path_type &, file_status, file_status) could not be inlined into boost::filesystem2::basic_directory_iterator<boost::filesystem2::basic_path<std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >,boost::filesystem2::wpath_traits> >::m_init(const basic_path<std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >,boost::filesystem2::wpath_traits> &). 1500-029: (W) WARNING: subprogram boost::filesystem2::basic_directory_entry<boost::filesystem2::basic_path<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,boost::filesystem2::path_traits> >::replace_filename(const string_type &, file_status, file_status) could not be inlined into boost::filesystem2::basic_directory_iterator<boost::filesystem2::basic_path<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,boost::filesystem2::path_traits> >::increment(). 1500-029: (W) WARNING: subprogram boost::filesystem2::basic_directory_entry<boost::filesystem2::basic_path<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,boost::filesystem2::path_traits> >::assign(const path_type &, file_status, file_status) could not be inlined into boost::filesystem2::basic_directory_iterator<boost::filesystem2::basic_path<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,boost::filesystem2::path_traits> >::m_init(const basic_path<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,boost::filesystem2::path_traits> &). "/gpfs/scratch/userexternal/jalfonsi/alps-2.0.0b4-r4959-src-with-boost/boost/boost/filesystem/v3/path.hpp", line 476.7: 1540-0716 (S) The template argument "boost::iterator" does not match the template parameter "class Derived". make[2]: *** [src/boost/CMakeFiles/boost.dir/__/__/boost/libs/filesystem/v3/src/operations.cpp.o] Error 1 make[1]: *** [src/boost/CMakeFiles/boost.dir/all] Error 2 make: *** [all] Error 2 Can someone tell me please if the compiler version could be the issue ? I see on Boost main page that 1.44 has been tested with Visual Age 11.1. I didn't have such problem with Boost 1.43 . Best regards Jessica

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boost MPI about finalize problem
by Jack Bryan 25 Oct '10

25 Oct '10

Hi I got a problem of MPI. I donot know whether it can be resolved in boost MPI. My program has 5 processes. All of them can run MPI_Finalize() and return 0. But, the whole program cannot be completed. In the MPI cluster job queue, it is still in running status. If I use 1 process to run it, no problem. Why ? My program: int main (int argc, char **argv) { MPI_Init(&argc, &argv); MPI_Comm_rank(MPI_COMM_WORLD, &myRank); MPI_Comm_size(MPI_COMM_WORLD, &mySize); MPI_Comm world; world = MPI_COMM_WORLD; if (myRank == 0) { do some things. } if (myRank != 0) { do some things. } cout << " I am rank " << rank << " I am before MPI_Finalize()" << endl; MPI_Finalize(); cout << " I am rank " << rank << " I am after MPI_Finalize()" << endl; return 0; } I can get the output " I am rank 0 (1, 2, ....) I am before MPI_Finalize() ". and " I am rank 0 I am after MPI_Finalize() " But, other processes do not printed out "I am rank ... I am after MPI_Finalize()" . It is weird. The process has reached the point just before MPI_Finalize(), why they are hanged there ? Are there other better ways to check this ? Any help is appreciated. And, some output files get wrong codes, which can not be readible. In 1-process case, the program can print correct results to these output files . Any help is appreciated. thanks Jack Oct. 24 2010

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Variadic Max Function
by Hossein Haeri 25 Oct '10

25 Oct '10

Dear all, Is there any variadic max function in Boost? I mean something which returns the max of all the arguments it takes -- no matter how many they are. (Feel free to correct me if this use of 'variadic' is not the correct terminology.) Please note that I'm not after working on ranges of arguments. I'm rather looking for a max function which is applicable in all the examples below: int m1 = max(a1, a2); int m2 = max(a1, a2, a3); ... int mk = max(a1, a2, ..., ak); TIA, --Hossein

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order of headers with Boost.Serialization and Boost.MPI
by Riccardo Murri 25 Oct '10

25 Oct '10

Hello, I'm writing a code that uses Boost.MPI to send some GMP (http://gmplib.org/) datatypes around. Since I do not want to change GMP, I'm using the "non-intrusive" serialization support (code in attached file "gmpxx_boost_serialization.hpp"). However, I'm running into a strange include-order mess: * If I include first my "gmpxx_boost_serialization.hpp" and _then_ "boost/mpi.h", then I get a slew of errors (attached file "errors.txt") * If I reverse the include order, and include "boost/mpi.h" _first_, then everything compiles fine. Is this to be expected, or am I doing something wrong in my code? For the record, I'm compiling on Ubuntu 10.10, gcc 4.4.5, arch. amd64. Thanks for any hint! Best regards, Riccardo Murri -- Riccardo Murri, Hadlaubstr. 150, 8006 Zürich (CH)

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General question about C++ [slightly off topic, sorry]
by Julien Martin 25 Oct '10

25 Oct '10

Hello, I am a beginner in C++. I learn using the Linux platform. What is the best place to look for general help about C++ please? Thanks in advance, J.

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Changes breaking behavior of operators /, /= and << in filesystem v3?
by Roel Vanhout 25 Oct '10

25 Oct '10

Hello, I enabled filesystem v3 after upgrading to 1.44. The api changes that caused the compiler to signal errors were rather easy to fix. However when running my program, it behaves differently from the way it used to. I narrowed it down to the following: char buf[MAX_PATH]; HRESULT res = ::SHGetFolderPath(NULL, CSIDL_APPDATA, NULL, SHGFP_TYPE_CURRENT, buf); boost::filesystem::path result(buf); // 'result' is after this "C:\Documents and Settings\rvanhout\Application Data" result /= "MyCompany"; At this point, 'result' *still* contains "C:\Documents and Settings\rvanhout\Application Data" whereas with v2 it used to contain "C:\Documents and Settings\rvanhout\Application Data\MyCompany\MyProduct". (environment: Windows (obviously) with VS 2008 (vc9)) There seem to be two way to get the desired behaviour: - initialize the path with a trailing slash, like this: boost::filesystem::path result(buf + std::string("/")); - convert 'buf' into a std::string first: std::string str(buf); boost::filesystem::path result(str); So I guess my code broke because the path is not initialized with the platform's native path encoding (although std::string is char also and it does work). Is this by design? It seems quite unintuitive to me. Second thing I was bit by is that the io streaming operator now seems to add quotes to a path with spaces in it when streaming a path object to an ostringstream. The string that is returned with .string() isn't quoted, of course, so my 'fix' is to not stream path objects anymore but add the .string() call. What's more important, is there a way to let the compiler signal these situations in my code? The way it is now, everything compiles but I have no way to know if it will actually work as it used to/should. Otherwise, it might be an idea to add #pragma warning statements to those parts for a release or two, to give people a heads up. Thanks. regards, Roel Vanhout

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32 bit time stamp to date and time
by Lloyd 25 Oct '10

25 Oct '10

Hi, I am writing a simple NTP client. NTP retuns the time as a 32bit value, as the seconds since 1900. using boost date time library is it possible to convert it to a date and time (year,month,day of week,day,hour,minute,second) ? Thanks, Lloyd ______________________________________ Scanned and protected by Email scanner

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