August 2006 - Boost-users - lists.preview.boost.org

[threads] extension proposal
by Ovanes Markarian 08 Aug '06

08 Aug '06

Hello, I would like to ask if it makes sence to introduce a data structure in boost::threads library, which implements a threads pool. Sometimes a system design can look like: Create a maximum of N threads and execute these threads with different tasks. If there more than N threads running then the threads_pool::get_thread(...) operation should block until one of threads gets ready. It is also possible to implement threads_pool::get_thread to use a policy which can block if the N is reached or return N+1 created thread. What I miss now in the threading library is the ability to reuse the thread. I think thread creation in the OS is an expensive task. If one has created thread, there should be a possiblity to reuse it. I understand it is possible to pass a function to the thread which executes tasks from the queue and therefore reuses threads, but this involves user implementation of such a function each time this programming pattern needs to be fullfilled. Would not it be a better idea to define a thread pool interface which has a synchronized queue (priority or not, should be customizeable) of tasks and pool of threads which are able to execute these tasks (boost::function0<void>) instances? I don't think I am the first person who comes up with this question... Would be really nice to hear your input on this issues or at least some links pointing to explanation, why this should not be done. With Kind Regards, Ovanes Markarian

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[Asio]How to compile the HelloWorld ?
by SP Z 08 Aug '06

08 Aug '06

Maybe this is a stupid problem , but I really don't konw how to find the right way. My compile environment is WinXP, Msys , MinGw , G++ 3.4.2, Boost 1.33.1, asio_0_3_7, bjam 3.1.13. I have already copy the header files of boost and asio into mingw/include I write the helloWorld.cpp follow the tutorial. #include <iostream> #include <boost/asio.hpp> #include <boost/date_time/posix_time/posix_time.hpp> int main() { boost::asio::io_service io; boost::asio::deadline_timer t(io, boost::posix_time::seconds(5)); t.wait(); std::cout << "Hello, world!\n"; return 0; } I write Jamroot as follow: exe hello : hello.cpp ; then I compile it in Msys, but link wrong happened(wrong messages see the end of this Email). Would you please help me to solve this problem . Thank you for(;;){} //forever $ bjam ...found 11 targets... ...updating 5 targets... MkDir1 bin MkDir1 bin\gcc MkDir1 bin\gcc\debug gcc.compile.c++ bin\gcc\debug\hello.o In file included from e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/detail/win_local_free_on_block_exit.hpp:27, from e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/system_exception.hpp:33, from e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/detail/win_mutex.hpp:26, from e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/detail/mutex.hpp:27, from e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/detail/service_registry.hpp:25, from e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/io_service.hpp:32, from e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/basic_io_object.hpp:20, from e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/basic_socket.hpp:20, from e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/basic_datagram_socket.hpp:25, from e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio.hpp:18, from hello.cpp:11: e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/detail/socket_types.hpp:31:5: warning: #warning Please define _WIN32_WINNT or _WIN32_WINDOWS appropriately e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/detail/socket_types.hpp:32:5: warning: #warning Assuming _WIN32_WINNT=0x0500 (i.e. Windows 2000 target) hello.cpp:24:2: warning: no newline at end of file gcc.link bin\gcc\debug\hello.exe bin\gcc\debug\hello.o: In function `ZN5boost4asio6detail31reactive_deadline_timer_serviceINS0_11time_traitsINS_10posix_time5ptimeEEENS1_14select_reactorILb1EEEE16shutdown_serviceEv':e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail12winsock_initILi2ELi0EE7do_initC1Ev[boost::asio::detail::winsock_init<2, 0>::do_init::do_init()]+0x1f): undefined reference to `WSAStartup@8' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops6selectEiP6fd_setS4_S4_P7timeval[boost::asio::detail::socket_ops::select(int, fd_set*, fd_set*, fd_set*, timeval*)]+0xc9): undefined reference to `select@20' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops13error_wrapperIiEET_S4_[int boost::asio::detail::socket_ops::error_wrapper<int>(int)]+0x8): undefined reference to `WSAGetLastError@0' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops9set_errorEi[boost::asio::detail::socket_ops::set_error(int)]+0x17): undefined reference to `WSASetLastError@4' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail12winsock_initILi2ELi0EE7do_initD1Ev[boost::asio::detail::winsock_init<2, 0>::do_init::~do_init()]+0x7): undefined reference to `WSACleanup@0' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops5closeEj[boost::asio::detail::socket_ops::close(unsigned int)]+0x19): undefined reference to `closesocket@4' bin\gcc\debug\hello.o: In function `main':e:/job/word-online/source/cpp/hello.cpp:15: undefined reference to `inet_addr@4' :e:/job/word-online/source/cpp/hello.cpp:23: undefined reference to `getsockname@12' bin\gcc\debug\hello.o: In function `ZN5boost4asio6detail31reactive_deadline_timer_serviceINS0_11time_traitsINS_10posix_time5ptimeEEENS1_14select_reactorILb1EEEE16shutdown_serviceEv':e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../.. o `closesocket@4' bin\gcc\debug\hello.o: In function `main':e:/job/word-online/source/cpp/hello.cpp:15: undefined reference to `inet_addr@4' :e:/job/word-online/source/cpp/hello.cpp:23: undefined reference to `getsockname@12' bin\gcc\debug\hello.o: In function `ZN5boost4asio6detail31reactive_deadline_timer_serviceINS0_11time_traitsINS_10posix_time5ptimeEEENS1_14select_reactorILb1EEEE16shutdown_serviceEv':e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops5ioctlEjlPm[boost::asio::detail::socket_ops::ioctl(unsigned int, long, unsigned long*)]+0x27): undefined reference to `ioctlsocket@12' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops6acceptEjP8sockaddrPi[boost::asio::detail::socket_ops::accept(unsigned int, sockaddr*, int*)]+0x27): undefined reference to `accept@12' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops13error_wrapperIjEET_S4_[unsigned int boost::asio::detail::socket_ops::error_wrapper<unsigned int>(unsigned int)]+0x8): undefined reference to `WSAGetLastError@0' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops7connectEjPK8sockaddri[boost::asio::detail::socket_ops::connect(unsigned int, sockaddr const*, int)]+0x27): undefined reference to `connect@12' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops6listenEji[boost::asio::detail::socket_ops::listen(unsigned int, int)]+0x20): undefined reference to `listen@8' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops4bindEjPK8sockaddri[boost::asio::detail::socket_ops::bind(unsigned int, sockaddr const*, int)]+0x27): undefined reference to `bind@12' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops10setsockoptEjiiPKvj[boost::asio::detail::socket_ops::setsockopt(unsigned int, int, int, void const*, unsigned int)]+0x35): undefined reference to `setsockopt@20' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops9get_errorEv[boost::asio::detail::socket_ops::get_error()]+0x7): undefined reference to `WSAGetLastError@0' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops6socketEiii[boost::asio::detail::socket_ops::socket(int, int, int)]+0x3f): undefined reference to `WSASocketA@24' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops4recvEjP7_WSABUFji[boost::asio::detail::socket_ops::recv(unsigned int, _WSABUF*, unsigned int, int)]+0x58): undefined reference to `WSARecv@28' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZNK5boost4asio6detail14fd_set_adapter6is_setEj[boost::asio::detail::fd_set_adapter::is_set(unsigned int) const]+0x14): undefined reference to `__WSAFDIsSet@8' :e:/program/mingw/mingw/bin/../lib/gcc/i686-pc-mingw32/3.4.2/../../../../include/boost/asio/deadline_timer_service.hpp:(.text$_ZN5boost4asio6detail10socket_ops4sendEjPK7_WSABUFji[boost::asio::detail::socket_ops::send(unsigned int, _WSABUF const*, unsigned int, int)]+0x58): undefined reference to `WSASend@28' collect2: ld returned 1 exit status "g++" -o "bin\gcc\debug\hello.exe" -Wl,--start-group "bin\gcc\debug\hello.o" -Wl,--end-group -g ...failed gcc.link bin\gcc\debug\hello.exe... ...failed updating 1 target... ...updated 4 targets... -- I'm Earth-Man. 我是地球人. --zsp(张沈鹏)

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[Serialization] Non-standard extensions used.
by Stephen Hewitt 08 Aug '06

08 Aug '06

The following is a dead simple example of using Boost.Serialization using an XML output archive which follows the patterns laid down in examples: /* \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/ */ #include <iostream> #include <boost/archive/xml_oarchive.hpp> #include <boost/serialization/nvp.hpp> // Warning level 4. #pragma warning(push, 4) #pragma message("********") struct MyData { MyData(int val) : m_Value(val) {} template<typename Archive> void serialize(Archive & ar, const unsigned int) { ar & BOOST_SERIALIZATION_NVP(m_Value); // <-- Warning here. } int m_Value; }; void main() { using namespace std; MyData d(3); boost::archive::xml_oarchive oa(cout); oa << BOOST_SERIALIZATION_NVP(d); <-- Warning here. } // Warning level back to normal. #pragma warning(pop) /* \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/ */ When compiling this code I get the following error: "warning C4239: nonstandard extension used : 'argument' : conversion from 'struct boost::serialization::nvp<struct MyData>' to 'struct boost::serialization::nvp<struct MyData> &' A reference that is not to 'const' cannot be bound to a non-lvalue" I tried MSVC 6 and "Visual C++ 2005" which can be downloaded from here: http://msdn.microsoft.com/vstudio/express/visualC/default.aspx Interestingly I could not get it to happen with "Microsoft Visual C++ Toolkit 2003". The warning seems valid to me. The "BOOST_SERIALIZATION_NVP" looks like this: -------------------------------------------------------------------------------------------------------------------------- #define BOOST_SERIALIZATION_NVP(name) \ boost::serialization::make_nvp(BOOST_PP_STRINGIZE(name), name) -------------------------------------------------------------------------------------------------------------------------- The "make_nvp" function looks like as follows: ------------------------------------------------------- nvp<T> make_nvp(const char * name, T & t){ return nvp<T>(name, t); } ------------------------------------------------------- "Operator<<", which is used in "main" is reproduced below: -------------------------------------------------------------------------------------- template<class Archive> class interface_oarchive { // ... Code removed ... // template<class T> Archive & operator<<(T & t){ this->This()->save_override(t, 0); return * this->This(); } // ... Code removed ... // }; -------------------------------------------------------------------------------------- So, to cut to the chase, "BOOST_SERIALIZATION_NVP" expands to a call to make_nvp" which returns a temporary which is bound to a non-const reference in "interface_oarchive::operator<<": this is not legal in standard C++ (unless I'm mistaken). It seems that if you follow to documentation and examples the resulting code isn't standard C++!?!

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[bgl] problem with topological_sort
by Renaud Lepere 08 Aug '06

08 Aug '06

I would like to use a graph and add/remove vertices frequently so i try to use a list for the vertices. At the begining, i would like to sort my vertices using dfs or topological_sort. But my program refuses to compile, apparently there is a problem with a property map for the colors. (c:/Boost/include/boost-1_33_1/boost/property_map.hpp:319: instantiated from `void boost::put....'). How can i make a dfs with such a graph ? Are there special requirements for using dfs or topologic_sort on a graph ? Thanks, Renaud. Following is a small example illlustrating the problem. #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/depth_first_search.hpp> #include <boost/graph/visitors.hpp> #include <boost/graph/topological_sort.hpp> #include <iterator> typedef boost::adjacency_list<boost::vecS, boost::listS, boost::bidirectionalS, int, int > Graph; typedef boost::graph_traits<Graph>::vertex_descriptor Vertex; typedef std::vector< Vertex > Vertices; int main() { Graph g; Vertices vs; boost::topological_sort(g, back_inserter(vs)); }

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Re: [Boost-users] [threads] extension proposal
by Oliver.Kowalke＠qimonda.com 08 Aug '06

08 Aug '06

> looks like what I need ;) The only question is, what does > stop() function of a defer_point? defer_pool::stop deactivates the threaded queue. All threads are awakened. > Will it stop all tasks > immediately or will it wait until the task queue is empty and > stop it then? It waits until all tasks were removed and processed from the queue. > Are there some plans to integrate this into the official > boost release? not yet > It would be nice to provide support for > different queue policies, like priority queue etc... May be > there are more wishes, like Vsevolod stated, by adding > support for threading or process policies... definetly - the library needs some improvements (fpr instance meber function defer should return a future). Oliver

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Re: [Boost-users] [threads] extension proposal
by Oliver.Kowalke＠qimonda.com 08 Aug '06

08 Aug '06

Hello Ovanes, please look into the boost vault (Concurrent Programming). I think the defer library fits your needs. The thread pool pre-spawns N threads which operate on a special queue (inside of the pool). If no task (boost::function objects) is queued all threads are set to sleep - if a task arives the queue one thread is awakened and fetches the task item from the queue and executes it (after that the thread goes to sleep again). The library was originally developed by Simon Meiklejohn. I've added the queue-stuff. regards, Oliver

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[program_options] Issues with boost::program_options freezing
by Zachary Mark 07 Aug '06

07 Aug '06

Hello, Our application is using boost::program_options to parse commandline arguments. We have found that when we perform our own builds of boost from source code, program_options freezes the application hard at variable points in the code (a step through in GDB confirms this). However, when we use pre-built binaries of the program_options library for any of our target OSes (Debian stable, Centos 4, Fedora 4) the application runs properly. We are also using the boost::thread library. Are there thread safety or interaction issues between thread and program_options that I am not aware of? We are using 1.32 due a change in the behavior of program_options in 1.33. This script shows how we are building boost. # run configure cd libs/config || fail-configure chmod +x configure || fail "error: could not change permissions on ${PACKAGE} configure script" ./configure || fail-configure cp user.hpp ../../boost/config/ cd ../.. # build and install libraries BOOST_LIBS="date_time filesystem program_options regex thread" for LIB in ${BOOST_LIBS}; do echo "Building library ${LIB}..." bjam -sTOOLS=gcc -sBUILD="release threading=multi" --with-${LIB} \ --layout="system" stage 2>&1 || \ fail "error: could not build boost library ${LIB}" bjam -sTOOLS=gcc -sBUILD="release threading=multi" --with-${LIB} --layout="system" \ --prefix=`pwd`/../../${INSTALL_DIR} install 2>&1 || \ fail "error: could not install boost library ${LIB}" done Thanks in advance. -- Zach

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Need help in serialization
by Anil Krishna 07 Aug '06

07 Aug '06

Hi All, Currently I am using the boost serialization library to serialize and the following structure: typedef list<int> testList; typedef testList::iterator lIter; typedef map<int, testList> testMap; typedef testMap::iterator tIter; testMap _tMap; template<class Archive> void serialize(Archive &ar, const unsigned int version) { ar & _tMap; } int main() { test_map tm; ofstream ofs("map_details.txt"); tm.fillMap(); //tm.display(); boost::archive::binary_oarchive oa(ofs); oa << (const test_map)tm; ofs.close(); test_map newTm; ifstream ifs("map_details.txt", std::ios::binary); boost::archive::binary_iarchive ia(ifs); ia >> newTm; ifs.close(); newTm.display(); } In the above code, I am saving the map to a binary file and retrieving it from the file. Instead of that I would want to serialize the data into a char buffer and restore it from the buffer. This is useful for message communication, where I would like to send the map as a message from one process to another using socket communications. Can you any one let me know, how this can be done in boost? Regards, Anil

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Re: [Boost-users] Need help in serialization
by Todd Greer 07 Aug '06

07 Aug '06

Anil Krishna wrote: > In the above code, I am saving the map to a binary file and retrieving it > from the file. Instead of that I would want to serialize the data into a > char buffer and restore it from the buffer. Serialize into a std::ostringstream, ship its buffer to the other receiver, construct a std::istringstream from the received buffer, then deserialize from the istringstream you just constructed. Read up on std::istringstream and std::ostringstream (in <sstream>) for the details. BTW, if the sender and receiver are on different platforms, or you happen to need to send the data through something that has a problem with binary data, you can use text_[io]archive instead of binary_[io]archive. HTH, Todd Greer <tgreer <at> affinegy dot com> Senior Software Developer, Affinegy LLC

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shmem on multi-user machine
by Steven Wooding 07 Aug '06

07 Aug '06

Hi Ion, I've noticed that the "file" /dev/shmem/sem.boost_shmem_shm_global_mutex keeps hanging around after my program finishes. This file has write permission only for the user that created it. When different user comes along a runs another program that uses shmem, it seg faults on sem_wait(), probably due to the file permissions. Should this global mutex be cleaned up after use? Or could the permissions be changed somehow to let other use it (though probably not a good idea if user A and user B run a shmem based program at the same time). Thanks for your advice. Cheers, Steve.

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