November 2010 - Boost-users

Boost parallel graph: a tree
by Hicham Mouline 19 Nov '10

19 Nov '10

Hello, Following a thread titled "Hybrid parallelism, no more + mpi+serialization, many questions ", I reproduce the main question here: A large calculation that I currently do serially and that I intend to parallelize is the maximum of the return values of a large number of evaluations of a given "function" in the mathematical sense. The number of arguments of the function is only known at runtime. Let's say it is determined at runtime that the number of arguments is 10, ie we have 10 arguments x0, ..., x9 Each argument can take a different number of values, for e.g. x0 can be x0_0, x0_1 .... x0_n0 x1 can be x1_0, x1_1, ...x1_n1 and so on...n0 and n1 are typically known at runtime and different . So serially, I run : f(x0_0, x1_0, ..., x9_0) f(x0_0, x1_0, ..., x9_1) ... f(x0_0, x1_0, ..., x9_n9) then with all the x8 then all the x7 ... then all the x0. More accurately, some of the arguments are constrained, for e.g., x3+x4+x5 =100 always I am looking at this as a vertical tree, from the top level (x0) down to the leaves (x9). x0 can have n0 values. For each of these nodes, there are n1 children, for each of these children, there are n2 children, and so on. The bottom-est children (for x9) are the leaves of the tree. The constraints that exist on some of the variables will remove a number of branches from the tree, however in my use case, this proportion is small. Once I reach the leaves, I evaluate a function with the 10 arguments selected by that branch. The objective is to obtain the minimum/maximum of return values over all evaluations. Is a tree a special case of a graph? Should I look at the parallel graph library? If so, what algorithm can help me with this? In the other thread, Brian provided a solution that I will implement if this problem doesn't lend itself to boost graph, regards,

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boost + openmpi link errors: missing openmpi libraries
by Hicham Mouline 19 Nov '10

19 Nov '10

hello,sorry for cross posting. I've built openmpi 1.4.3 on win32 and generated only 4 release libs: 3,677,712 libmpi.lib 336,466 libmpi_cxx.lib 758,686 libopen-pal.lib 1,307,592 libopen-rte.lib I've installed the boostPro 1.44 mpi library with the installer. But I have link errors: 1>libboost_mpi-vc90-mt-1_44.lib(broadcast.obj) : error LNK2001: unresolved external symbol _MPI_Bcast@20 is boostpro's mpi lib against openmpi or another MPI implementation? regards,

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Compile time Error when including boost interprocess sync/named_mutex.hpp
by bcg 19 Nov '10

19 Nov '10

Hello,I have trouble compiling a program to share memory between processes that uses #include <boost/interprocess/sync/named_mutex.hpp>Version: boost_135_0During compilation I am getting following error. Can anyone give me any inputs to resolve this...Thanks c:commonboost_1_35_0boostinterprocesssyncemulationnamed_creation_functor.hpp(33) : error C2061: syntax error : identifier 'address' 1> c:commonboost_1_35_0boostinterprocesssyncemulationnamed_creation_functor.hpp(49) : see reference to function template instantiation 'void boost::interprocess::detail::named_creation_functor<T>::construct<Arg>(void *,void *) const' being compiled 1> with 1> [ 1> T=boost::interprocess::interprocess_mutex, 1> Arg=boost::interprocess::detail::named_creation_functor_no_arg 1> ] 1> c:commonboost_1_35_0boostinterprocesssyncemulationnamed_creation_functor.hpp(41) : while compiling class template member function 'bool boost::interprocess::detail::named_creation_functor<T>::operator ()(void *,size_t,bool) const' 1> with 1> [ 1> T=boost::interprocess::interprocess_mutex 1> ] 1> c:commonboost_1_35_0boostinterprocesssyncnamed_mutex.hpp(174) : see reference to class template instantiation 'boost::interprocess::detail::named_creation_functor<T>' being compiled 1> with 1> [ 1> T=boost::interprocess::interprocess_mutex 1> ]

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[thread] boost::call_once() optimization idea on Win32
by Thomas Jarosch 19 Nov '10

19 Nov '10

Hello, here's a small optimization idea for boost::call_once() on Win32. The code currently looks like this: ---------------------------------------------- template<typename Function> void call_once(once_flag& flag,Function f) { // Try for a quick win: if the procedure has already been called // just skip through: long const function_complete_flag_value=0xc15730e2; if(::boost::detail::interlocked_read_acquire(&flag)!=function_complete_flag_value) { void* const mutex_handle(::boost::detail::create_once_mutex(&flag)); BOOST_ASSERT(mutex_handle); detail::win32::handle_manager const closer(mutex_handle); detail::win32_mutex_scoped_lock const lock(mutex_handle); if(flag!=function_complete_flag_value) { f(); BOOST_INTERLOCKED_EXCHANGE(&flag,function_complete_flag_value); } } } ---------------------------------------------- The initial flag value of zero (=BOOST_ONCE_INIT) is set at load time via static initialization. It should be safe to do a non-interlocked read of the flag like this: ---------------------------------------------- if(flag!=function_complete_flag_value && ::boost::detail::interlocked_read_acquire(&flag)!=function_complete_flag_value) ---------------------------------------------- If our non-interlocked read would see something different than "function_complete_flag_value", we still do the interlocked read, too. For normal operation inside a thread safe singleton, this saves us from always issuing a memory barrier. Any flaws with this approach? Also one more (silly?) question: "flag" is not a volatile variable. Does boost::detail::interlocked_read_acquire() make sure the value doesn't get cached inside a register? IMHO we lock the mutex and we might still hold a cached, old value of "flag" in a register. -> Do we need an interlocked read here, too? Or mark the flag type "volatile"? (http://msdn.microsoft.com/en-us/magazine/cc163405.aspx#S3 look at figure 7 and the text below) Best regards, Thomas Jarosch

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Re: [Boost-users] Hybrid parallelism, no more + mpi+serialization, many questions
by Hicham Mouline 19 Nov '10

19 Nov '10

>On Fri, Nov 19, 2010 at 7:14 AM, Hicham Mouline <hicham(a)mouline.org>; wrote:>>> Here's how I'd probably do this using a pull model:>>> <snip>>>> Brian>>>> Hi Brian,>>>> Thanks for the solution. I think I'll go first just with monothread mpi processes.>>>> Can I use MPI splitting the communicators following my tree's shape? Does MPI allow splitting world, and then splitting >>again, then again....?>>>> rds,>-----Original Message----->From: "Brian Budge" [brian.budge(a)gmail.com]>Date: 19/11/2010 03:36 PM>To: boost-users(a)lists.boost.org>Subject: Re: [Boost-users] Hybrid parallelism, no more + mpi+serialization, many questions>>I'm not positive exactly what you mean. Can you explain in more detail? >>Maybe you're referring to spawning? You can spawn processes, but I'm>very inexperienced with that. It sounds, however, like you'll always>have at least millions of tasks. For ease of programming, I'd>recommend just using mpirun to launch as many processes as you can>afford, and pass tasks to them when they request work to do. Not>understanding your problem in enough detail, that's the best I can>recommend (for example, is it easy to just "jump" to a starting point>in your tree, or do you have to traverse from the start?)>>BrianI was referring to the section "Managing communicators" in http://www.boost.org/doc/libs/1_44_0/doc/html/mpi/tutorial.html#mpi.communi… There is a split() function.Imagine I have 1000 processes. And I have for the variable x0 , 10 possible values, so the root(nil) of the tree has 10 children.I thought to split the world communicator (1000 processes) into 10 groups (10 processes each), and then continue the splitting until the process group holds less processes than possible values for the current variable x_i and then give the remainder of the tree to that process group.Is this "splitting" a costly operation? This splitting, it's not spawning at all (as far as I understand).Obviously the 1000 processes would be all launched at startup.I have to traverse the tree from the top to the bottom.Thanks,

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Boost.DateTime: ISO Timestamp Parsing Bug
by Peter Klotz 19 Nov '10

19 Nov '10

Hello I already sent this patch earlier this year but got no response. boost::posix_time::from_iso_string() converts "20100713" into "20100713T201007.300000" which is obviously wrong. The error is caused by boost::date_time::split(). The attached patch corrects split() so that an exception is thrown later in parse_delimited_time_duration(). The problem is reproducible in Boost 1.42.0 and 1.44.0. This simple example demonstrates the issue: const boost::posix_time::ptime time=boost::posix_time::from_iso_string("20100713"); std::cout << "Converted: " << boost::posix_time::to_iso_string(time) << std::endl; Converted: 20100713T201007.300000 Maybe someone can apply this patch. Regards, Peter.

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Valgrind false positive in make_shared
by Dave Steffen 19 Nov '10

19 Nov '10

Peter Dimov wrote: > Frank Mori Hess wrote: > > Another bit of info: getting rid of the static_cast in > > boost::detail::sp_forward makes both the compiler warning and valgrind > > error go away, although I have no idea why. > > Interesting... which version of GCC? Without the static_cast, it shouldn't > compile, as rvalue references no longer bind to lvalues. In fact, I see that > I added the static_cast in [61574] for that very reason. I got this bad behavior with GCC 4.4.4. It goes away with GCC 4.2.4. These are the only two compilers I have at hand at the moment, but I can try others if it would be useful. I get very nervous when Valgrind is unhappy -- it's the only tool for such things that we've ever found to work worth a damn. :-) Thanks for looking in to this. -- Dave Steffen, Ph.D. - Software Engineer Numerica Corporation <http://www.numerica.us> 4850 Hahns Peak Drive, Suite 200 Loveland, Colorado 80538 main (970) 461-2000 x 227 direct (970) 612-2327 Email: dave.steffen(a)numerica.us fax (970) 461-2004 This message and any attachments are intended only for the individual or entity to which the message is addressed. This is a private message and may contain privileged information. If you are neither the intended recipient nor the agent responsible for delivering the message to the intended recipient, you are hereby notified that any review, retransmission, dissemination, or taking of any action in reliance upon, the information in this communication is strictly prohibited, and may be unlawful. If you feel you have received this communication in error, please notify me immediately by returning this email to me and deleting it from your computer.

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[Filesystem V3] problems on Solaris
by Paul Graphov 19 Nov '10

19 Nov '10

Hello Boost Users, I've got problems using Boost.Filesystem v3 under Sun Solaris 10. If I compile this example with -DBOOST_FILESYSTEM_VERSION=3 http://www.boost.org/doc/libs/1_44_0/libs/filesystem/v3/example/tut3.cpp It works like that: bash-3.00# /tmp/bb /etc "/etc" exists, but is neither a regular file nor a directory If I remove this flag (to make it use Filesystem v2) it works as expected. bash-3.00# /opt/csw/gcc4/bin/g++ --version g++ (Blastwave.org Inc. Mon Aug 23 11:16:32 GMT 2010) 4.5.1 Copyright (C) 2010 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. bash-3.00# uname -a SunOS localhost 5.10 Generic_120012-14 i86pc i386 i86pc Thanks.

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[netlib] throwing exceptions with http_client.cpp
by Christian Henning 19 Nov '10

19 Nov '10

Hi there, I'm trying to run http_client.cpp taken from the netlib examples. But unfortunately it's throwing a lot of exceptions. The line: cout << body(response) << endl; results into the following exceptions: First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x00bddcd0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: [rethrow] at memory location 0x00000000.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x00bddcd0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: [rethrow] at memory location 0x00000000.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x00bddcd0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: [rethrow] at memory location 0x00000000.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x00bddcd0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: [rethrow] at memory location 0x00000000.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x00bddcd0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: [rethrow] at memory location 0x00000000.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x002cece0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x00bddcd0.. First-chance exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: [rethrow] at memory location 0x00000000.. Unhandled exception at 0x000007fefdd0aa7d in test_netlib_vc10.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::system::system_error> at memory location 0x002cece0.. here is my stack: msvcr100d.dll!_CxxThrowException(void * pExceptionObject=0x000000000030ee20, const _s__ThrowInfo * pThrowInfo=0x000000013f526cd8) Line 157 C++ test_netlib_vc10.exe!boost::exception_detail::clone_impl<boost::system::system_error>::rethrow() Line 421 C++ test_netlib_vc10.exe!boost::rethrow_exception(const boost::shared_ptr<boost::exception_detail::clone_base const > & p={...}) Line 413 C++ test_netlib_vc10.exe!boost::detail::future_object_base::wait(bool rethrow=true) Line 170 + 0x11 bytes C++ test_netlib_vc10.exe!boost::detail::future_object<std::basic_string<char,std::char_traits<char>,std::allocator<char> > >::get() Line 331 C++ test_netlib_vc10.exe!boost::shared_future<std::basic_string<char,std::char_traits<char>,std::allocator<char> > >::get() Line 847 + 0x12 bytes C++ test_netlib_vc10.exe!boost::network::http::async_message<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::network::tags::http,boost::network::tags::simple>,boost::network::tags::async>,boost::network::tags::tcp>,boost::network::tags::default_string> >::body() Line 107 + 0x18 bytes C++ test_netlib_vc10.exe!boost::network::http::impl::body_wrapper<boost::network::http::basic_response<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::network::tags::http,boost::network::tags::simple>,boost::network::tags::async>,boost::network::tags::tcp>,boost::network::tags::default_string> > >::operator std::basic_string<char,std::char_traits<char>,std::allocator<char> >() Line 30 + 0x12 bytes C++ test_netlib_vc10.exe!boost::network::http::body<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::network::tags::http,boost::network::tags::simple>,boost::network::tags::async>,boost::network::tags::tcp>,boost::network::tags::default_string> >(const boost::network::http::basic_response<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::mpl::inherit2<boost::network::tags::http,boost::network::tags::simple>,boost::network::tags::async>,boost::network::tags::tcp>,boost::network::tags::default_string> > & message={...}) Line 41 + 0x1f bytes C++ test_netlib_vc10.exe!main(int argc=2, char * * argv=0x00000000004f7850) Line 86 + 0x15 bytes C++ test_netlib_vc10.exe!__tmainCRTStartup() Line 555 + 0x19 bytes C test_netlib_vc10.exe!mainCRTStartup() Line 371 C I'm using boost trunk with Visual Studio 10 compiling x64 bit code. Anyone any idea what going on here? Thanks, Christian

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The cpp-netlib Release 0.8 is Out Now!
by Dean Michael Berris 19 Nov '10

19 Nov '10

Hi Everyone, advanced apologies for the cross-post. To those interested and watching the cpp-netlib project's progress, this afternoon Philippine time I just packaged and released the latest installment of the cpp-netlib project. Release 0.8 features: * An asynchronous HTTP server template, supporting asynchronous handler invocation and asynchronous writing to the established HTTP connection on the handler side. An example of one use for this is included in the library which implements a simple static web server, benchmarked with Apache AB on a dual core Intel Core 2 CPU with 2GB RAM to be able to serve a 10kb file at 4700 requests per second on 64-bit Linux 2.6.36. You can find out more about the example here: http://goo.gl/5mVuY * More in-depth documentation covering the HTTP Client and Server APIs, now hosted online as well. Read the documentation at http://cpp-netlib.github.com/0.8/ * A simple thread pool implementation that uses Boost.Asio underneath, with a simple API for posting nullary function objects as tasks. The number of threads to run is configurable as a constructor parameter -- this is especially required by the asynchronous HTTP server template, where handlers are queued to be executed. The library is released under the Boost Software License, and is being developed for future submission to the Boost C++ Library. You can download the latest and previous releases from http://github.com/cpp-netlib/cpp-netlib/downloads. Have a great day everyone and I look forward to your very valuable feedback! -- Dean Michael Berris deanberris.com

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