July 2015 - Boost-users - lists.preview.boost.org

Problem with boost.log in a multithread application
by Rajalakshmi Iyer 17 Jul '15

17 Jul '15

Hello, I am using Boost.Log to produce 2 logs for a multi-thread application. There are 2 singleton channel_mt loggers corresponding to 2 files. Several threads continuously write different messages to the two loggers. Log file rotation is enabled on both loggers and in the event of rotation, the logs are collected into a different folder. All of this works as expected for a while, except randomly (but surely at some point) - I start seeing a stream of messages like - [2015-Jul-17 01:11:26.532653] (info): *** Exception: boost::filesystem::last_write_time: No such file or directory: "/var/infinity/rtb/auction_log" [2015-Jul-17 01:11:26.532896] (info): Boost Exception - libs/log/src/text_file_backend.cpp(1160): Throw in function void boost::log::v2_mt_posix::sinks::text_file_backend::consume(const boost::log::v2_mt_posix::record_view&, const string_type&) This goes on for a while and then my application hangs. It is not entirely clear whether this incidence happens only during size based rotation or even otherwise. Any pointers on how to approach this issue would be greatly appreciated. Thanks Raj -- This email and any attachments to it may be confidential and are intended solely for the use of the individual to whom it is addressed. Any views or opinions expressed are solely those of the author and do not necessarily represent those of BlisMedia Ltd, a company registered in England and Wales with registered number 06455773. Its registered office is 3rd Floor, 101 New Cavendish St, London, W1W 6XH, United Kingdom. If you are not the intended recipient of this email, you must neither take any action based upon its contents, nor copy or show it to anyone. Please contact the sender if you believe you have received this email in error.

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Is this a known bug in lexical_cast<double> ?
by TILLMAN, MICHAEL D9 16 Jul '15

16 Jul '15

We're using boost 1.51. Management is reluctant to upgrade because the software is for manned space flight and our current boost version has been stable. Wanted to see if there was a known bug with boost::lexical_cast<double>. We're seeing failures on what appear to be valid float strings. When we catch the exception, and simply do a second cast on the same string, the cast succeeds. The Code fragment: try { dVal = boost::lexical_cast<double>(theValue); } catch(boost::bad_lexical_cast &eX) { ... more code ... firstAttemptFailed = true; } // If the first cast succeeded, don't bother to attempt it again. if(firstAttemptFailed == true) { // Let the API throw the actual exception if the second attempt also fails. dVal = boost::lexical_cast<double>(theValue); } The string sequence this fails on is: ... ... "7104", "0.416666699999999999983", "0.22222224", "4.08233160000000000001", "1.81436960000000000002", ... ... It fails on the last string, "1.81.....", in the actual program, but when compiled into a simple test program, it succeeds. If there is a known bug, we may be able to get a Boost upgrade installed. Thanks, Mike

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Re: [Boost-users] Query regarding interest in my submitting plf::colony to Boost
by Colin Humphries 16 Jul '15

16 Jul '15

> I don't think anything related to multithreading should be done by such kind of container. Disturbed by that comment I just wanted to add for the benefit of anyone just starting out with multi-threading that in my experience containers are entirely safe for multi-threading PROVIDED that you're only reading from them (i.e. they are passed by const &). This is by far the most efficient way to pass common information into parallel threads (all threads read the same data). For containers required to return a result, the approach that works for me is to create a vector of containers and dedicate one to each thread. The result containers must be guaranteed to remain in scope until all threads have completed so I usually make them global. The only challenge is how to efficiently coalesce the partial results. Get this wrong (or use too many threads) and the performance gain from multi-threading quickly evaporates. Colin Humphries

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[Graph] pgRouting and boost.graph
by Vicky Vergara 16 Jul '15

16 Jul '15

Hello, We work on the pgRouting project and we are updating our code to use Boost.Graph. For the moment our intention is to have a V2.1 of pgRouting modifying 3 of our routing functions, and I am working on the documentation. I am making references to Boost.Graph, I would like some one from Boost.Graph team to check if the references I am making are according to your requirements and /or give us some suggestions. The following link takes you to the tentative documentation that mentions Boost.Graph. https://github.com/pgRouting/pgrouting/blob/develop_2_1_0/src/dijkstra/doc/… Thanks in advance. Vicky

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Boost graph parallel issue
by Mayank Bakshi 16 Jul '15

16 Jul '15

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How do I build boost with a specific compiler flag?
by Gagnon, Joseph - 0553 - MITLL 15 Jul '15

15 Jul '15

Hello, I am developing a C++ application on a Linux (CentOS 6.6) platform with gcc 4.8.2. I need to build the Boost libraries I'm using (Regex and others) such that the code is compiled with the "-fPIC" (position-independent code) option. I looked around on the Boost web site and found information about a configure script and something called Boost.Config. I quickly got overwhelmed. What do I need to do to have the Boost build system use this flag to build its libraries? Is it something fairly simple, or do I need to invoke a complicated set of steps? Thanks, Joe Gagnon Engineer II Group 53 - Secure Resilient Systems and Technology MIT Lincoln Laboratory Lexington, MA

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[Test] Did This Pass, Or Didn't it?
by Merrill Cornish 15 Jul '15

15 Jul '15

Here is the Boost Test assertion: BOOST_CHECK_EXCEPTION(dummyOpr->setOperand(emptyValue), DiGSE::fail, fail_msg); Here is the test execution log message: info: check 'incorrect exception DiGSE::fail is caught' has passed I have only one exception: *DiGSE::fail* (derived from *std::exception*). It is the /only /exception that appears in the *BOOST_CHECK_EXCEPTION()* assertions. So, what does "incorrect exception *DiGSE::fail*" mean? If *DiGSE::fail* was caught, then that part is correct. If the message means that some /other/ exception was caught, then this is a Really Poor way of phrasing that information. Or, did the predicate return *false* (which, in my case, means the exception message is wrong)? But if the wrong exception was caught /or/ the predicate returned *false*, then why was the assertion declared "has passed"? Merrill Cornish

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Test: Different versions of doc (raffienficiaud)
by Florian Lindner 15 Jul '15

15 Jul '15

Hello, additionally to the official documentation of boost test at [1], I have found a different version at [2]. This looks like the official documentation but describes much more features and more comprehensive. However, although not the development version at [3]. What does the version from raffienficiaud describes? Is this some own extensions of him? Thanks, Florian [1] http://www.boost.org/doc/libs/1_58_0/libs/test/doc/html/index.html [2] http://raffienficiaud.github.io/test/index.html [3] http://svn.boost.org/svn/boost/trunk/libs/test/doc/html/index.html

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Boost.DLL formal review is ongoing
by Vladimir Prus 15 Jul '15

15 Jul '15

The formal review of Boost.DLL library by Antony Polukhin is nearing the end of the first week. As of today, over 100 people read through the library's tutorial, suggesting quite some interest. However, no reviews were submitted yet. Please take the time to post your thoughts - even if you don't have time to do a full review, or try the library, comments on design and interfaces are still very valuable. The summary of the library features and review checklists are reproduced below. Boost.DLL is a C++98 library for comfortable work with DLL and DSO. Library provides a portable across platforms way to: - load libraries at runtime - import and export any native functions and variables - make alias names for C++ mangled functions and symbols - query libraries/objects and executables for sections and exported symbols - self loading and self querying - getting program and module location by exported symbol The documentation can be found at: http://apolukhin.github.io/Boost.DLL/index.html and the source can be obtained at: https://github.com/apolukhin/Boost.DLL Please post your reviews on the mailing list and if possible, answer the following questions: - Should the library be accepted? - How useful is it? - What's your evaluation of - Design - Implementation - Documentations - Tests - How much effort did you put into your evaluation? - Did you attempt to use the library? On what systems and compilers? Thanks, Volodya _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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the stability of breadth_first_visit in BGL
by breadbread1984 14 Jul '15

14 Jul '15

I am wondering if breadth_first_visit can always get the same sequence of vertex no matter whether the graph is serialized and deserialized again. Thx

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