January 2011 - Boost-users - lists.preview.boost.org

[boost.thread] function call and functor in thread creation: performance
by Boost lzw 22 Jan '11

22 Jan '11

Hi, everyone, A new thread can be created using boost thread either from a function or a functor as the entry point of the new thread, as: void thread_function(); boost::thread thrd(&function); class functor { public: inline void operator()(); }; functor f; boost::thread thrd(f); Is there a performance difference between these two? In an ordinary C++ program, can I claim that calling f() 1000 times gives better performance than calling thread_function() 1000 times, because the functor is hinted "inline" even the hint is igored by my compiler? Is f() the same as a function call in term of performance? Thanks in advance. Robert

3 3

boost.iterators - iterator_facade issue with aligned types.
by Christoph Heindl 21 Jan '11

21 Jan '11

Hi, It seems to me that boost::iterator_facade cannot cope with aligned types when the 'Reference = use_default' template argument is not a reference, which can happen if transform_iterator is used to return the result of a temporay calculation (by value of course). Inside iterator_facade.hpp struct operator_arrow_result { //... static type make(Reference x) { return implicit_cast<type>(&x); } }; Reference here is passed by value. Since Reference has alignment the compiler reports an error. The issue was resolved once i changed that code to struct operator_arrow_result { //... typedef typename mpl::if_< is_reference<Reference> , Reference , typename add_reference<Reference>::type >::type input_type; static type make(input_type x) { return implicit_cast<type>(&x); } }; I wonder about any side effects this would cause? My lousy research is based boost 1.43. That part of the code seems to be unchanged for the current trunk. Best regards, Christoph

2 4

Re: [Boost-users] Assertion `__null != bpos' failed in /inclu de/boost/archive/detail/oserializer.hpp:436
by ktomaszewski＠zunit.com 21 Jan '11

21 Jan '11

2 1

Re: [Boost-users] Assertion `__null != bpos' failed in /inclu de/boost/archive/detail/oserializer.hpp:436
by ktomaszewski＠zunit.com 21 Jan '11

21 Jan '11

1 0

Re: [Boost-users] Assertion `__null != bpos' failed in /inclu de/boost/archive/detail/oserializer.hpp:436
by ktomaszewski＠zunit.com 21 Jan '11

21 Jan '11

1 0

Assertion `__null != bpos' failed in /inclu de/boost/archive/detail/oserializer.hpp:436
by ktomaszewski＠zunit.com 20 Jan '11

20 Jan '11

2 1

Thread-specific pointers versus MFC (Microsoft)
by Stephen Nuchia 20 Jan '11

20 Jan '11

I see a thread about this issue from 2009, with no resolution. A possible patch was mentioned but there was never a followup. We picked up the thread-specific pointer goodness with 1.35, under Visual Studio 2008. We stayed with that combination ever since, for stability. Now I'm looking at VS2010 and 1.44. To support Microsoft's thread model in DLL (dynamically linked libraries) in 1.35 required the user to intercept library unload events. Shortly after 1.35, the boost thread library was enhanced to take care of this for you. The hook it uses, however, conflicts with the use of that same hook by Microsoft's MFC library, when you are building an "MFC Extension DLL" specifically. We have a bunch of that going on. The conflict ends up being detected at link time, like this: 1>libboost_thread-vc100-mt-gd-1_44.lib(tss_pe.obj) : error LNK2005: _pRawDllMain already defined in Table.obj The archive discussion http://thread.gmane.org/gmane.comp.lib.boost.user/46509/focus=46706 What is the current thinking on this issue? I don't see any #ifdef logic in the boost headers that looks like it might be intended to address this, do I need to hack it myself or is there an established work-around? And don't dog me about MFC. Some of the code I'm dealing with is still in FORTRAN, and some is 25-year-old C. Thanks! -swn

1 0

[BGL] Threshold for betweenness_centrality_clustering()
by Cedric Laczny 20 Jan '11

20 Jan '11

Hi, I would like to use boost::betweenness_centrality_clustering() to search a graph for specific clusters. The documentation talks about a "Done" object, which I assume is a functor, similar to the predicates used in filtered_graph(). So in order to decide whether the algorithm should stop the clustering, it probably needs a threshold to decide if it should further iterate and remove edges to decompose the graph. My questions now are: - Does someone perhaps have an example for the usage of this algorithm? I only found documentation on "betweenness.centrality.clustering {RBGL}" for Gnu R, which doesn't bring me very far. - Is there some sort of rule-of-thumb to start with for finding this termination threshold or if there is some more-or-less methodical way of finding out a reasonable threshold? Best, Cedric

4 4

regex __sync_fetch_and_add_4 issue when compiling to 32 bit Linux
by Ákos Maróy 20 Jan '11

20 Jan '11

Hi, I seem to have a problem when trying to link C++ code that refers to the boost regex library, when this is done so that it is compiled on a 64 bit Linux system, but for a 32 bit target. I get the following error: libboost_regex.so: undefined reference to `__sync_fetch_and_add_4' collect2: ld returned 1 exit status I wonder what needs to be done to fix this. steps to reproduce: - compile boost for 32 bit, by: ./bjam architecture=x86 address-model=32 --prefix=/path/to/boost install - try to compile & link a very simple sample code (see the end of the mail) g++ -m32 -L//path/to/boost/lib -I/path/to/boost/include -lboost_regex -o hello hello.cxx /path/to/boost/lib/libboost_regex.so: undefined reference to `__sync_fetch_and_add_4' collect2: ld returned 1 exit status when compiling the same code for 64 bit, it compiles fine. seeing this thread: http://lists.boost.org/Archives/boost/2008/04/135586.php I also tried the following: g++ -m32 -DBOOST_SP_USE_PTHREADS -L//path/to/boost/lib -I/path/to/boost/include -lboost_regex -o hello hello.cxx g++ -m32 -DBOOST_SP_DISABLE_THREADS -L//path/to/boost/lib -I/path/to/boost/include -lboost_regex -o hello hello.cxx but I got the same results :( any help would be appreciated. Akos details: platfrom: Ubuntu 10.10 64 bit compiler: g++ 4.4.4 boost: 1.45.0 the sample code I used is very minimalistic: #include <boost/regex.hpp> int main(void) { boost::regex LF("\\\\n"), CR("\\\\r"), TAB("\\\\t"); return 0; }

4 8

[polygon] Quadratic performance when handling any angle polygons
by Josh Pieper 19 Jan '11

19 Jan '11

Hello, First: we are using boost 1.45.0 with gcc -O3 on Ubuntu 10.04. (Although similar problems appear with VS2008 on Windows 7). We have been observing performance with boost::polygon that is significantly worse than we were expecting when working with any angle polygons. Namely quadratic instead of the expected O(n log n). While profiling, I noticed that most of the time is spent in the overload of line_intersection::validate_scan at detail/scan_arbitrary.hpp:154 which is commented as: "//quadratic algorithm to do same work as optimal scan for cross checking". I have inlined our test program below, and some performance results measured by instruction count under "valgrind --tool=callgrind". Is this poor performance because our data is degenerate, or because a vestigal quadratic double check is still being applied? Regards, Josh Pieper Performance results for n=10..110 measured in instructions to complete the following test program: 10 2363923 20 4427849 30 8695564 40 15642559 50 25530188 60 39081335 70 57151093 80 79278939 90 107261217 100 140674559 110 164340087 -------------------------- #include <boost/lexical_cast.hpp> #include <boost/type.hpp> #include <boost/polygon/polygon.hpp> #include <boost/polygon/gmp_override.hpp> int main(int argc, char** argv) { typedef boost::polygon::point_data<int32_t> point_type; typedef boost::polygon::polygon_set_data<int32_t> polygon_set; typedef polygon_set::value_type value_type; int32_t sample_data[] = { -15417, -53418, 0, 0, -1, -15417, -53418, 37998, -68834, 1, 37998, -68834, 53415, -15416, 1, 0, 0, 53415, -15416, -1, -20188, -37532, 15869, 4788, -1, -20188, -37532, 22129, -73587, 1, 22129, -73587, 58187, -31268, 1, 15869, 4788, 58187, -31268, -1, -12388, -58060, -4666, -3001, -1, -12388, -58060, 42669, -65781, 1, 42669, -65781, 50390, -10722, 1, -4666, -3001, 50390, -10722, -1, -16452, -51370, 2015, 1078, -1, -16452, -51370, 35988, -69834, 1, 35988, -69834, 54455, -17386, 1, 2015, 1078, 54455, -17386, -1, -9812, -61108, -7737, -5548, -1, -9812, -61108, 45744, -63182, 1, 45744, -63182, 47819, -7623, 1, -7737, -5548, 47819, -7623, -1, -19695, -27418, 25940, 4341, -1, -19695, -27418, 12063, -73050, 1, 12063, -73050, 57697, -41291, 1, 25940, 4341, 57697, -41291, -1, -11871, -58680, -5330, -3460, -1, -11871, -58680, 43338, -65220, 1, 43338, -65220, 49879, -10000, 1, -5330, -3460, 49879, -10000, -1, -12303, -10547, -4768, -65638, 1, -4768, -65638, 50314, -58104, 1, 42779, -3013, 50314, -58104, -1, -12303, -10547, 42779, -3013, -1, -10105, -60739, -7415, -5202, -1, -10105, -60739, 45425, -63428, 1, 45425, -63428, 48115, -7891, 1, -7415, -5202, 48115, -7891, -1, -9937, -60912, -7600, -5360, -1, -9937, -60912, 45609, -63249, 1, 45609, -63249, 47946, -7697, 1, -7600, -5360, 47946, -7697, -1, -20348, -32184, 16794, -73555, 1, 16794, -73555, 58164, -36414, 1, 21022, 4957, 58164, -36414, -1, -20348, -32184, 21022, 4957, -1, -10796, -8606, -6653, -64049, 1, -6653, -64049, 48788, -59906, 1, 44644, -4463, 48788, -59906, -1, -10796, -8606, 44644, -4463, -1, -16263, -16858, 1613, -69511, 1, 1613, -69511, 54257, -51638, 1, 36381, 1014, 54257, -51638, -1, -16263, -16858, 36381, 1014, -1, -20298, -33057, 17817, -73534, 1, 17817, -73534, 58292, -35421, 1, 20177, 5056, 58292, -35421, -1, -20298, -33057, 20177, 5056, -1, -11941, -9961, -5271, -65159, 1, -5271, -65159, 49923, -58490, 1, 43253, -3292, 49923, -58490, -1, -11941, -9961, 43253, -3292, -1, -19046, -44168, 28939, -72250, 1, 28939, -72250, 57020, -24267, 1, 9035, 3815, 57020, -24267, -1, -19046, -44168, 9035, 3815, -1, -10926, -8703, -6528, -64127, 1, -6528, -64127, 48893, -59729, 1, 44495, -4305, 48893, -59729, -1, -10926, -8703, 44495, -4305, -1, -19113, -43924, 28699, -72304, 1, 28699, -72304, 57076, -24496, 1, 9263, 3883, 57076, -24496, -1, -19113, -43924, 9263, 3883, -1, -18256, -21581, 6351, -71437, 1, 6351, -71437, 56204, -46832, 1, 31598, 3024, 56204, -46832, -1, -18256, -21581, 31598, 3024, -1, -20282, -31991, 16756, -73456, 1, 16756, -73456, 58219, -36421, 1, 21181, 5045, 58219, -36421, -1, -20282, -31991, 21181, 5045, -1, -19379, -25528, 10293, -72546, 1, 10293, -72546, 57309, -42875, 1, 27637, 4143, 57309, -42875, -1, -19379, -25528, 27637, 4143, -1, -16209, -16633, 1396, -69371, 1, 1396, -69371, 54130, -51767, 1, 36526, 970, 54130, -51767, -1, -16209, -16633, 36526, 970, -1, -18570, -22483, 7245, -71726, 1, 7245, -71726, 56484, -45912, 1, 30669, 3330, 56484, -45912, -1, -18570, -22483, 30669, 3330, -1, -19900, -40189, 24948, -73049, 1, 24948, -73049, 57806, -28203, 1, 12958, 4657, 57806, -28203, -1, -19900, -40189, 12958, 4657, -1, -20322, -36011, 20774, -73460, 1, 20774, -73460, 58220, -32367, 1, 17124, 5082, 58220, -32367, -1, -20322, -36011, 17124, 5082, -1, -555, -68328, 53079, -53671, 1, 38424, -43, 53079, -53671, -1, -15210, -14699, 38424, -43, -1, -15210, -14699, -555, -68328, 1, 21671, -61840, 21718, -61835, 1, 14689, -61655, 21718, -61835, -1, 14689, -61655, 42185, -65881, 1, 42185, -65881, 50629, -10931, 1, 23134, -6705, 50629, -10931, -1, 16104, -6524, 23134, -6705, -1, 16057, -6529, 16104, -6524, -1, 16057, -6529, 21671, -61840, 1, -7903, -63005, 47680, -60927, 1, 45602, -5370, 47680, -60927, -1, -9981, -7449, 45602, -5370, -1, -9981, -7449, -7903, -63005, 1, }; value_type edge_list; size_t num_elements = sizeof(sample_data) / (sizeof(*sample_data) * 5); if (argc > 1) { num_elements = std::min(num_elements, boost::lexical_cast<size_t>(argv[1])); } for (size_t i = 0; i < num_elements; i++) { value_type::value_type edge_plus; int32_t* record = &sample_data[i * 5]; edge_plus.first.first = point_type(record[0], record[1]); edge_plus.first.second = point_type(record[2], record[3]); edge_plus.second = record[4]; edge_list.push_back(edge_plus); } polygon_set pset; pset.set(edge_list); pset.clean(); }

2 2