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does gather blocks?
by alev mutlu 27 Mar '10

27 Mar '10

Hi all, I am scattering some data, each client works it share, and finally the master collects all the data and proceeds in its way. The problem is that clients finish their work in different time and I wonder if gather blocks until all workers finish. I am getting segmentation faults, and I am not sure if it is due to synchronization or something else. Any idea?

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[serialization] Potential problems with void_caster
by Bogdan 27 Mar '10

27 Mar '10

I am trying this again, because if it needs a fix it would be nice to make it into the next boost release. I get an access violation after explicitly unloading a DLL that contains serialization code for a series of classes. I believe there might be a bug in void_caster::recursive_unregister(): that function member is called in the destructors of the void caster template classes. It searches the set inside void_caster_registry singleton for all the entries that are descendants of the current one (i.e., the void_caster being destroyed) and performs the following operations: - delete the shortcuts. - remove the corresponding entries from the set. However, void_caster::recursive_unregister() doesn't remove from the registrar the entry corresponding to the current void_caster(). This creates the problem below: Consider a scenario where a dll containing some serialization functionality is loaded explicitly at runtime (i.e., using LoadLibrary() on Windows or dlopen on Unix). There are no parent-child relationships among the serialized classes registered by that DLL: all serialized classes are derived from one abstract base. While unloading the library, its void_caster singletons are destroyed but there are no shortcuts to remove from the global registrar since there are no parent-child relationships. All entries corresponding to those are still in the global registrar and point to the void_caster singletons ALREADY DESTROYED AND DISCARDED. When the main process exits, the registrar repeats the traversal for whatever executable-bound void_caster singletons are about to be destroyed. During these subsequent traversals, void_caster::recursive_unregister() visits the entries left after the previous explicit dll download and tries to identify the parent-child relationship. In doing so, it accesses the dangling vc pointers generating access violations: void_cast.cpp(Line 286): const void_caster * vc = *it; void_cast.cpp(Line 287): if(vc->m_parent == this){ //<--------------------- here is the access violation I can reproduce the crash systematically, but I am not 100% sure about the reason or whether a simple unregistration is enough. I believe this is (again) a question for Robert Ramey, but I thank for any feedback I might get. Bogdan PS On a different tack I would like to confirm I tested Robert fix (@60273) for multiple registrations and it looks good in my runs. Thank you!

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Boost Graph: vertex class has no copy constructor
by Trevor Harmon 26 Mar '10

26 Mar '10

Hi, I'm using the Boost Graph library to construct a directed graph: typedef boost::directed_graph<BasicBlock> Graph; The vertex class, "BasicBlock", is not my own; it comes from the LLVM project. Unfortunately, the declaration above causes a slew of compiler errors (see below) that appear to be related to BasicBlock's copy constructor. Sure enough, I checked BasicBlock.h, and its copy constructor is declared private and is not even implemented. There appears to be some sort of design issue that prevents this class from having a copy constructor. Is there some workaround for this on the Boost Graph side, or must vertex classes always have a copy constructor? Thanks, Trevor /Users/twharmon/Development/boost_1_42_0/boost/pending/property.hpp: In constructor ‘boost::property<Tag, T, Base>::property(const T&) [with Tag = boost::vertex_bundle_t, T = llvm::BasicBlock, Base = boost::no_property]’: Clepsydra.cpp:46: instantiated from here /Users/twharmon/Development/LLVM/llvm-2.7/llvm-2.7-src/include/llvm/ BasicBlock.h:81: error: ‘llvm::BasicBlock::BasicBlock(const llvm::BasicBlock&)’ is private /Users/twharmon/Development/boost_1_42_0/boost/pending/property.hpp: 31: error: within this context /Users/twharmon/Development/boost_1_42_0/boost/pending/property.hpp: In copy constructor ‘boost::property<boost::vertex_bundle_t, llvm::BasicBlock, boost::no_property>::property(const boost::property<boost::vertex_bundle_t, llvm::BasicBlock, boost::no_property>&)’: /Users/twharmon/Development/boost_1_42_0/boost/pending/property.hpp: 22: instantiated from ‘typename boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, typename boost::graph_detail::vertex_prop<Prop>::type>, boost::property<boost::edge_index_t, unsigned int, typename boost::graph_detail::edge_prop<EdgeProp>::type>, GraphProp, boost::listS>::vertex_descriptor boost::directed_graph<VertexProp, EdgeProp, GraphProp>::add_vertex(const typename boost::graph_detail::vertex_prop<Prop>::type&) [with VertexProp = llvm::BasicBlock, EdgeProp = boost::no_property, GraphProp = boost::no_property]’ /Users/twharmon/Development/boost_1_42_0/boost/graph/ directed_graph.hpp:454: instantiated from ‘typename boost::directed_graph<VertexProp, EdgeProp, GraphProp>::vertex_descriptor boost::add_vertex(const typename boost::directed_graph<VertexProp, EdgeProp, GraphProp>::vertex_property_type&, boost::directed_graph<VP, EP, GP>&) [with VP = llvm::BasicBlock, EP = boost::no_property, GP = boost::no_property]’ Clepsydra.cpp:46: instantiated from here /Users/twharmon/Development/LLVM/llvm-2.7/llvm-2.7-src/include/llvm/ BasicBlock.h:81: error: ‘llvm::BasicBlock::BasicBlock(const llvm::BasicBlock&)’ is private /Users/twharmon/Development/boost_1_42_0/boost/pending/property.hpp: 22: error: within this context cc1plus: warnings being treated as errors /Users/twharmon/Development/boost_1_42_0/boost/pending/property.hpp: In copy constructor ‘boost::property<boost::vertex_index_t, unsigned int, boost::property<boost::vertex_bundle_t, llvm::BasicBlock, boost::no_property> >::property(const boost::property<boost::vertex_index_t, unsigned int, boost::property<boost::vertex_bundle_t, llvm::BasicBlock, boost::no_property> >&)’: /Users/twharmon/Development/boost_1_42_0/boost/pending/property.hpp: 22: warning: synthesized method ‘boost::property<boost::vertex_bundle_t, llvm::BasicBlock, boost::no_property>::property(const boost::property<boost::vertex_bundle_t, llvm::BasicBlock, boost::no_property>&)’ first required here /Users/twharmon/Development/boost_1_42_0/boost/graph/ directed_graph.hpp: In member function ‘typename boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, typename boost::graph_detail::vertex_prop<Prop>::type>, boost::property<boost::edge_index_t, unsigned int, typename boost::graph_detail::edge_prop<EdgeProp>::type>, GraphProp, boost::listS>::vertex_descriptor boost::directed_graph<VertexProp, EdgeProp, GraphProp>::add_vertex(const typename boost::graph_detail::vertex_prop<Prop>::type&) [with VertexProp = llvm::BasicBlock, EdgeProp = boost::no_property, GraphProp = boost::no_property]’: /Users/twharmon/Development/boost_1_42_0/boost/graph/ directed_graph.hpp:154: warning: synthesized method ‘boost::property<boost::vertex_index_t, unsigned int, boost::property<boost::vertex_bundle_t, llvm::BasicBlock, boost::no_property> >::property(const boost::property<boost::vertex_index_t, unsigned int, boost::property<boost::vertex_bundle_t, llvm::BasicBlock, boost::no_property> >&)’ first required here

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Linking boost in Visual Studio VC++ project
by Federico Golfrè Andreasi 26 Mar '10

26 Mar '10

Hi ! I'm trying to find out how to link boost libraries under windows to a visual studio VC++ project (that will be a .dll library). Where can I find some information ?! I've compiled the boost libraries and followed the instruction found at: http://www.boost.org/doc/libs/1_35_0/more/getting_started/windows.html but when I build the project it gives me an error trying to find a libboost_filesystem-vc80-mt-gd-1_41.lib, but no one libraries build starts with the 'lib' prefix ? Why he search for them ? Thank you, Federico

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Boost::spirit program crashes
by Lars Rohwedder 26 Mar '10

26 Mar '10

Here my stripped version still crashes with segfault: ----<snio>---- #include <boost/spirit.hpp> #include <iostream> using namespace boost::spirit; struct Configurable { const char* name; // name of the configurable module const rule<>& parser; // parser for config items, normally // a couple of OR-connected terms. }; rule<> __ = ch_p(' '); // separator char. was a bit more complex // in the original code std::string conn, port, ident_name, ident_pw; /* // the original parser crashes with segfault: const Configurable cfg = { "Hardtest", +( *__ | ("connect" >> __ >> str_p[assign_a(conn)] >> ':' >> int_p[assign_a(port)]) | ("identity" >> __ >> str_p[assign_a(ident_name)] >> __ >> str_p[assign_a(ident_pw)] ) | "hard" ) }; */ // a simplicistic parser that still crashes: const Configurable cfg = { "Hardtest", +( __ ) }; int main(int argc, char** argv) { // original config string: // "connect foo.bar:123 identity root fF2.oby!sy" or the like. parse("hard ", cfg.parser); // <--- CRASHES! // this works: // parse("hard ", +(__) ); }; ----<snap>---- The stack trace of GNU gdb is: Program received signal SIGSEGV, Segmentation fault. 0x000000000040184e in boost::spirit::impl::rule_base<boost::spirit::rule<boost::spirit::nil_t, boost::spirit::nil_t, boost::spirit::nil_t>, boost::spirit::rule<boost::spirit::nil_t, boost::spirit::nil_t, boost::spirit::nil_t> const&, boost::spirit::nil_t, boost::spirit::nil_t, boost::spirit::nil_t>::parse_main<boost::spirit::scanner<char const*, boost::spirit::scanner_policies<boost::spirit::iteration_policy, boost::spirit::match_policy, boost::spirit::action_policy> > > (this=0x7fff29fcea10, scan=@0x7fff29fcea00) at /usr/include/boost/spirit/core/non_terminal/impl/rule.ipp:189 189 hit = rule_base_access::get(*derived_this) (gdb) bt #0 0x000000000040184e in boost::spirit::impl::rule_base<boost::spirit::rule<boost::spirit::nil_t, boost::spirit::nil_t, boost::spirit::nil_t>, boost::spirit::rule<boost::spirit::nil_t, boost::spirit::nil_t, boost::spirit::nil_t> const&, boost::spirit::nil_t, boost::spirit::nil_t, boost::spirit::nil_t>::parse_main<boost::spirit::scanner<char const*, boost::spirit::scanner_policies<boost::spirit::iteration_policy, boost::spirit::match_policy, boost::spirit::action_policy> > > (this=0x7fff29fcea10, scan=@0x7fff29fcea00) at /usr/include/boost/spirit/core/non_terminal/impl/rule.ipp:189 #1 0x00000000004018f7 in boost::spirit::impl::rule_base<boost::spirit::rule<boost::spirit::nil_t, boost::spirit::nil_t, boost::spirit::nil_t>, boost::spirit::rule<boost::spirit::nil_t, boost::spirit::nil_t, boost::spirit::nil_t> const&, boost::spirit::nil_t, boost::spirit::nil_t, boost::spirit::nil_t>::parse<boost::spirit::scanner<char const*, boost::spirit::scanner_policies<boost::spirit::iteration_policy, boost::spirit::match_policy, boost::spirit::action_policy> > > (this=0x7fff29fcea10, scan=@0x7fff29fcea00) at /usr/include/boost/spirit/core/non_terminal/impl/rule.ipp:171 #2 0x000000000040197b in boost::spirit::parse<char const*, boost::spirit::rule<boost::spirit::nil_t, boost::spirit::nil_t, boost::spirit::nil_t> > (first_=@0x7fff29fcea58, last=@0x7fff29fcea68, p=@0x7fff29fcea10) at /usr/include/boost/spirit/core/impl/parser.ipp:28 #3 0x0000000000401a34 in boost::spirit::parse<char, boost::spirit::rule<boost::spirit::nil_t, boost::spirit::nil_t, boost::spirit::nil_t> > (str=0x402420 "hard ", p=@0x7fff29fcea10) at /usr/include/boost/spirit/core/impl/parser.ipp:45 #4 0x0000000000400973 in main (argc=1, argv=0x7fff29fceb88) at cfgTest.cc:38 I am using boost 1.35 (yes, it is quite old. Is this a bug in boost that is fixed in newer versions? I didn't found something related in the changelogs) on Linux x86_64, gcc 4.3.2 (Debian "Lenny"). Perhaps somebody knows an answer except "use spirit 2!" :-) Lars R.

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error with "-std=c++0x" flag
by girish hilage 26 Mar '10

26 Mar '10

Hi, I am using "-std=c++0x" flag while compiling my program but it gives me errors as follows : /usr/lib/gcc/i586-redhat-linux/4.4.0/../../../../include/c++/4.4.0/tr1_impl/type_traits: In function ‘bool boost::filesystem::is_empty(const boost::filesystem::path&)’: /usr/lib/gcc/i586-redhat-linux/4.4.0/../../../../include/c++/4.4.0/tr1_impl/type_traits:326: error: ‘template<class _Tp> struct std::is_empty’ is not a function, /usr/include/boost/filesystem/operations.hpp:361: error: conflict with ‘template<class Path> typename boost::enable_if<boost::filesystem::is_basic_path<Path>, bool>::type boost::filesystem::is_empty(const Path&)’ /usr/include/boost/filesystem/operations.hpp:660: error: in call to ‘is_empty’ /usr/lib/gcc/i586-redhat-linux/4.4.0/../../../../include/c++/4.4.0/tr1_impl/type_traits: In function ‘bool boost::filesystem::is_empty(const boost::filesystem::wpath&)’: /usr/lib/gcc/i586-redhat-linux/4.4.0/../../../../include/c++/4.4.0/tr1_impl/type_traits:326: error: ‘template<class _Tp> struct std::is_empty’ is not a function, /usr/include/boost/filesystem/operations.hpp:361: error: conflict with ‘template<class Path> typename boost::enable_if<boost::filesystem::is_basic_path<Path>, bool>::type boost::filesystem::is_empty(const Path&)’ /usr/include/boost/filesystem/operations.hpp:662: error: in call to ‘is_empty’ Is there any workaround to this problem? Regards, Girish

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[MPI] Code example leaks memory
by Yves Daemen 26 Mar '10

26 Mar '10

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timed waits
by Just C 26 Mar '10

26 Mar '10

I was looking at this article about conditon_variables. http://www.justsoftwaresolutions.co.uk/threading/condition-variable-spuriou… For a timeout, the article has the following sample program with condition variables. template<typename Duration> bool timed_wait_and_pop(Data& popped_value, Duration const& wait_duration) { boost::system_time const timeout=boost::get_system_time()+wait_duration; boost::mutex::scoped_lock lock(the_mutex); while(the_queue.empty()) { if(!the_condition_variable.timed_wait(lock,timeout)) return false; } popped_value=the_queue.front(); the_queue.pop(); return true; } However, shouldn't this program instead start with boost::mutex::scoped_lock lock(the_mutex, timeout); if(!lock.owns()) return false; i.e. shouldn't it also take care of getting stuck while locking the mutex. i.e. if the timeout is 5 seconds & the getting the lock itself takes 10 seconds, then, the earlier the program will return is 10+ seconds.

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template typedef?
by Roland Bock 26 Mar '10

26 Mar '10

Hi, I wonder if there is some easy way to express the following incorrect code in a correct way? typedef template<class T> boost::function<void(const T&)> foo_function; template<> foo_function<int> my_foo = bind(example_function); Regards, Roland

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Re: [Boost-users] [program-options] static linked example segfaults for exception
by Neetu Garg 26 Mar '10

26 Mar '10

ThanksVladimir and David, I tried "-static" without "-static-libgcc" and "-Wl,-Bstatic" and it worked fine. My test sample that uses program option and single threaded works fine with the above change. But my other application that is multi threaded (using boost thread API) and uses program option still segfaults. When I try to add "libpthread" and "-lboost_thread-gcc41-mt" in linking I start getting segfaults. LDFLAGS= -static -L/u/neetug/Projects/performance/perfstat_cluster/lib -lpthread -lboost_program_options-gcc41-mt -lboost_filesystem-gcc41-mt -lboost_system-gcc41-mt -lboost_thread-gcc41-mt -lrt Appreciate you help Regards, NG ________________________________ From: David Kaplan <davkaplan(a)gmail.com> To: boost-users(a)lists.boost.org Sent: Mon, March 22, 2010 11:29:26 AM Subject: Re: [Boost-users] [program-options] static linked example segfaults for exception >>> g++ testprogramoptions.o -static-libgcc >>> -Wl,-Bstatic -L/u/neetug/Projects/performance/perfstat_cluster/lib >>> -lboost_program_options-gcc41-mt -lpthread -o testprogramoptions > >This is not the best way to link statically. Did you try just -static >>option, without -static-libgcc and -Wl,-Bstatic? > Or you could try: -l:libboost_program_options-gcc41- mt

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