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• C# Monte Carlo Incremental Risk Calculation optimisation, random numbers, parallel execution

  - by m3ntat

  My current task is to optimise a Monte Carlo Simulation that calculates Capital Adequacy figures by region for a set of Obligors. It is running about 10 x too slow for where it will need to be in production and number or daily runs required. Additionally the granularity of the result figures will need to be improved down to desk possibly book level at some stage, the code I've been given is basically a prototype which is used by business units in a semi production capacity. The application is currently single threaded so I'll need to make it multi-threaded, may look at System.Threading.ThreadPool or the Microsoft Parallel Extensions library but I'm constrained to .NET 2 on the server at this bank so I may have to consider this guy's port, http://www.codeproject.com/KB/cs/aforge_parallel.aspx. I am trying my best to get them to upgrade to .NET 3.5 SP1 but it's a major exercise in an organisation of this size and might not be possible in my contract time frames. I've profiled the application using the trial of dotTrace (http://www.jetbrains.com/profiler). What other good profilers exist? Free ones? A lot of the execution time is spent generating uniform random numbers and then translating this to a normally distributed random number. They are using a C# Mersenne twister implementation. I am not sure where they got it or if it's the best way to go about this (or best implementation) to generate the uniform random numbers. Then this is translated to a normally distributed version for use in the calculation (I haven't delved into the translation code yet). Also what is the experience using the following? http://quantlib.org http://www.qlnet.org (C# port of quantlib) or http://www.boost.org Any alternatives you know of? I'm a C# developer so would prefer C#, but a wrapper to C++ shouldn't be a problem, should it? Maybe even faster leveraging the C++ implementations. I am thinking some of these libraries will have the fastest method to directly generate normally distributed random numbers, without the translation step. Also they may have some other functions that will be helpful in the subsequent calculations. Also the computer this is on is a quad core Opteron 275, 8 GB memory but Windows Server 2003 Enterprise 32 bit. Should I advise them to upgrade to a 64 bit OS? Any links to articles supporting this decision would really be appreciated. Anyway, any advice and help you may have is really appreciated.

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• MySql multiple selects batching in .net

  - by Amith George

  I have a situation in my application. For each x-axis point in my chart, I am plotting 5 y-axis values. To calculate each of these 5 values, I need to make 4 different queries. Ie, for each x-axis point I need to fire 20 sql queries. Now, I need to plot 40 such points in the my chart. Its resulting in a pathetic performance where it takes close to a minute to get all the data back from the database. Each of 4 different queries consists of a join between 2 tables. One has only 6 rows. The other close to 10,000. Each of the 4 queries has different WHERE clauses, so they are different queries. For each point in the x-axis, only the values for the where clauses change. I have tried combining each of the 4 queries into one big string. Basically batch the four selects. These are again batched for each y-axis value. So, for each x-axis point, I am now firing one big command that consists of 20 different select statements. Technically, I should be experiencing a big performance boost, right? Instead of hitting the db 40x5x4 = 800 times, I am now hitting it just 40 times. But instead of taking 60 seconds, it taking 50-55 seconds... not much of a help. I am using MySql 5.1, and the 6.1 version of its .Net connector. What can I do to improve the performance? Edit: One of the 4 queries is as follows: SELECT SUM(TIME_TO_SEC(TIMEDIFF(T1.col2, T1.col1))* T2.col1 / (3600 *1000)) AS TotalTime FROM Table T1 JOIN Table T2 ON T1.col3 = T2.col3 WHERE T1.col4 = 'i' AND T1.col1 >= '2009-12-25 00:00:00' AND T1.col2 <= '2009-12-26 00:00:00'; The other 3 queries are similar, only the where clause changes slightly. This set of 4 queries is fired 5 times. The first 3 times against the join of table T1 and T2, passing in different values for col4. And the next two times against the join of table T3 and T2 passing in different values for col4. These 5 values are the y-axis values for a particular x-axis point. The data returned by all these queries is the same format. so, we tried doing a UNION ALL on all these queries. No substantial difference. One strange thing, however, after indexing the foreign key on the table T1 [while it contained over a lakh records], the queries were using the index, but they had become slower. At times, the queries would take double the time to return the data.

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• Sysadmin 101: How can I figure out why my server crashes and monitor performance?

  - by bflora

  I have a Drupal-powered site that seems to have neverending performance problems. It was butt-slow about 5 months ago. I brought in some guys who installed nginx for anonymous visitors, ajaxified a few queries so they wouldn't fire during page load, and helped me find a few bottlenecks in the code. For about a month, the site was significantly faster, though not "fast" by any stretch of the word. Meanwhile, I'm now shelling out $400/month to Slicehost to host a site that gets less than 5,000/uniques a day. Yes, you read that right. Go Drupal. Recently the site started crashing again and is slow again. I can't afford to hire people to come in, study my code from top to bottom, and make changes that may or may not help anymore. And I can't afford to throw more hardware at the problem. So I need to figure out what the problem is myself. Questions: When apache crashes, is it possible to find out what caused it to crash? There has to be a way, right? If so, how can I do this? Is there software I can use that will tell me which process caused my server to die? (e.g. "Apache crashed because someone visited page X." or "Apache crashed because you were importing too many RSS items from feed X.") There's got to be a way to learn this, right? What's a good, noob-friendly way to monitor my current apache performance? My developer friends tell me to "just use Top, dude," but Top shows me a bunch of numbers without any context. I have no clue what qualifies as a bad number or a good number in Top, or which processes are relevant and which aren't. Are there any noob-friendly server monitoring tools out there? Ideally, I could have a page that would give me a color-coded indicator about how apache is performing and then show me a list of processes or pages that are sucking right now. This way, I could know when performance is bad and then what's causing it to be so bad. Why does PHP memory matter? My apparently has a 30MB memory foot print. Will it run faster if I bring that number down? Thanks for any advice. I spent a year or so trying to boost my advertising income so I could hire a contractor to solve my performance woes. I didn't want to have to learn all this sysadmin voodoo. I'm now resigned to the fact that might not have a choice.

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• Segmentation fault in std function std::_Rb_tree_rebalance_for_erase ()

  - by Sarah

  I'm somewhat new to programming and am unsure how to deal with a segmentation fault that appears to be coming from a std function. I hope I'm doing something stupid (i.e., misusing a container), because I have no idea how to fix it. The precise error is Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address: 0x000000000000000c 0x00007fff8062b144 in std::_Rb_tree_rebalance_for_erase () (gdb) backtrace #0 0x00007fff8062b144 in std::_Rb_tree_rebalance_for_erase () #1 0x000000010000e593 in Simulation::runEpidSim (this=0x7fff5fbfcb20) at stl_tree.h:1263 #2 0x0000000100016078 in main () at main.cpp:43 The function that exits successfully just before the segmentation fault updates the contents of two containers. One is a boost::unordered_multimap called carriage; it contains one or more struct Infection objects that contain two doubles. The other container is of type std::multiset< Event, std::less< Event EventPQ called ce. It is full of Event structs. void Host::recover( int s, double recoverTime, EventPQ & ce ) { // Clearing all serotypes in carriage // and their associated recovery events in ce // and then updating susceptibility to each serotype double oldRecTime; int z; for ( InfectionMap::iterator itr = carriage.begin(); itr != carriage.end(); itr++ ) { z = itr->first; oldRecTime = (itr->second).recT; EventPQ::iterator epqItr = ce.find( Event(oldRecTime) ); assert( epqItr != ce.end() ); ce.erase( epqItr ); immune[ z ]++; } carriage.clear(); calcSusc(); // a function that edits an array cout << "Done with sync_recovery event." << endl; } The last cout << line appears immediately before the seg fault. I hope this is enough (but not too much) information. My idea so far is that the rebalancing is being attempting on ce after this function, but I am unsure why it would be failing. (It's unfortunately very hard for me to test this code by removing particular lines, since they would create logical inconsistencies and further problems, but if experienced programmers still think this is the way to go, I'll try.)

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• Can I append to a preprocessor macro?

  - by JCSalomon

  Is there any way in standard C—or with GNU extensions—to append stuff to a macro definition? E.g., given a macro defined as #define quux_list X(foo) X(bar) can I append X(bas) so that it now expands as if I’d defined it #define quux_list X(foo) X(bar) X(bas)? I’m playing with discriminated/tagged unions along these lines: struct quux_foo { int x; }; struct quux_bar { char *s; }; struct quux_bas { void *p; }; enum quux_type {quux_foo, quux_bar, quux_bas}; struct quux { enum quux_type type; union { struct quux_foo foo; struct quux_bar bar; struct quux_bas bas; } t; }; I figure this is a good place for the X-macro. If I define a macro #define quux_table X(foo) X(bar) X(bas) the enumeration & structure can be defined thus, and never get out of sync: #define X(t) quux_ ## t, enum quux_type {quux_table}; #undef X #define X(t) struct quux_ ## t t; struct quux { enum quux_type type; union {quux_table} t; }; #undef X Of course, the quux_* structures can get out of sync, so I’d like to do something like this, only legally: struct quux_foo { int x; }; #define quux_table quux_table X(foo) struct quux_bar { char *s; }; #define quux_table quux_table X(bar) struct quux_bas { void *p; }; #define quux_table quux_table X(bas) (Well, what I really want to be able to do is something like member_struct(quux, foo) { int x; }; but I’m well aware that macros cannot be (re)defined from within macros.) Anyhow, that’s my motivating example. Is there a way to accomplish this? Boost.Preprocessor examples are fine, if you can show me how to make the X-macro technique work with that library.

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• Is there any reasonable use of a function returning an anonymous struct?

  - by Akanksh

  Here is an (artificial) example of using a function that returns an anonymous struct and does "something" useful: #include <iostream> template<typename T> T* func( T* t, float a, float b ) { if(!t) { t = new T; t->a = a; t->b = b; } else { t->a += a; t->b += b; } return t; } struct { float a, b; }* foo(float a, float b) { if(a==0) return 0; return func(foo(a-1,b), a, b); } int main() { std::cout << foo(5,6)->a << std::endl; std::cout << foo(5,6)->b << std::endl; void* v = (void*)(foo(5,6)); float* f = (float*)(v); //[1] delete f now because I know struct is floats only. std::cout << f[0] << std::endl; std::cout << f[1] << std::endl; delete[] f; return 0; } There are a few points I would like to discuss: As is apparent, this code leaks, is there anyway I can NOT leak without knowing what the underlying struct definition is? see Comment [1]. I have to return a pointer to an anonymous struct so I can create an instance of the object within the templatized function func, can I do something similar without returning a pointer? I guess the most important, is there ANY (real-world) use for this at all? As the example given above leaks and is admittedly contrived. By the way, what the function foo(a,b) does is, to return a struct containing two numbers, the sum of all numbers from 1 to a and the product of a and b. EDIT: Maybe the line new T could use a boost::shared_ptr somehow to avoid leaks, but I haven't tried that. Would that work?

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• Turn class "Interfaceable"

  - by scooterman

  Hi folks, On my company system, we use a class to represent beans. It is just a holder of information using boost::variant and some serialization/deserialization stuff. It works well, but we have a problem: it is not over an interface, and since we use modularization through dlls, building an interface for it is getting very complicated, since it is used in almost every part of our app, and sadly interfaces (abstract classes ) on c++ have to be accessed through pointers, witch makes almost impossible to refactor the entire system. Our structure is: dll A: interface definition through abstract class dll B: interface implementation there is a painless way to achieve that (maybe using templates, I don't know) or I should forget about making this work and simply link everything with dll B? thanks Edit: Here is my example. this is on dll A BeanProtocol is a holder of N dataprotocol itens, wich are acessed by a index. class DataProtocol; class UTILS_EXPORT BeanProtocol { public: virtual DataProtocol& get(const unsigned int ) const { throw std::runtime_error("Not implemented"); } virtual void getFields(std::list<unsigned int>&) const { throw std::runtime_error("Not implemented"); } virtual DataProtocol& operator[](const unsigned int ) { throw std::runtime_error("Not implemented"); } virtual DataProtocol& operator[](const unsigned int ) const { throw std::runtime_error("Not implemented"); } virtual void fromString(const std::string&) { throw std::runtime_error("Not implemented"); } virtual std::string toString() const { throw std::runtime_error("Not implemented"); } virtual void fromBinary(const std::string&) { throw std::runtime_error("Not implemented"); } virtual std::string toBinary() const { throw std::runtime_error("Not implemented"); } virtual BeanProtocol& operator=(const BeanProtocol&) { throw std::runtime_error("Not implemented"); } virtual bool operator==(const BeanProtocol&) const { throw std::runtime_error("Not implemented"); } virtual bool operator!=(const BeanProtocol&) const { throw std::runtime_error("Not implemented"); } virtual bool operator==(const char*) const { throw std::runtime_error("Not implemented"); } virtual bool hasKey(unsigned int field) const { throw std::runtime_error("Not implemented"); } }; the other class (named GenericBean) implements it. This is the only way I've found to make this work, but now I want to turn it in a truly interface and remove the UTILS_EXPORT (which is an _declspec macro), and finally remove the forced linkage of B with A.

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• Help with infrequent segmentation fault in accessing struct

  - by Sarah

  I'm having trouble debugging a segmentation fault. I'd appreciate tips on how to go about narrowing in on the problem. The error appears when an iterator tries to access an element of a struct Infection, defined as: struct Infection { public: explicit Infection( double it, double rt ) : infT( it ), recT( rt ) {} double infT; // infection start time double recT; // scheduled recovery time }; These structs are kept in a special structure, InfectionMap: typedef boost::unordered_multimap< int, Infection > InfectionMap; Every member of class Host has an InfectionMap carriage. Recovery times and associated host identifiers are kept in a priority queue. When a scheduled recovery event arises in the simulation for a particular strain s in a particular host, the program searches through carriage of that host to find the Infection whose recT matches the recovery time (double recoverTime). (For reasons that aren't worth going into, it's not as expedient for me to use recT as the key to InfectionMap; the strain s is more useful, and coinfections with the same strain are possible.) assert( carriage.size() > 0 ); pair<InfectionMap::iterator,InfectionMap::iterator> ret = carriage.equal_range( s ); InfectionMap::iterator it; for ( it = ret.first; it != ret.second; it++ ) { if ( ((*it).second).recT == recoverTime ) { // produces seg fault carriage.erase( it ); } } I get a "Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address..." on the line specified above. The recoverTime is fine, and the assert(...) in the code is not tripped. As I said, this seg fault appears 'randomly' after thousands of successful recovery events. How would you go about figuring out what's going on? I'd love ideas about what could be wrong and how I can further investigate the problem.

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• Function-Local Static Const variable Initialization semantics.

  - by Hassan Syed

  The questions are in bold, for those that cannot be bothered reading a question in depth. This is a followup to this question. It is to do with the initialization semantics of static variables in functions. Static variables should be initialized once, and their internal state might be altered later - as I (currently) do in the linked question. However, the code in question does not require the feature to change the state of the variable later. Let me clarrify my position, since I don't require the string object's internal state to change. The code is for a trait class for meta programming, and as such would would benifit from a const char * const ptr -- thus Ideally a local cost static const variable is needed. My educated guess is that in this case the string in question will be optimally placed in memory by the link-loader, and that the code is more secure and maps to the intended semantics. This leads to the semantics of such a variable "The C++ Programming language Third Edition -- Stroustrup" does not have anything (that I could find) to say about this matter. All that is said is that the variable is initialized once when the flow of control of the thread first reaches the code. This leads me to ponder if the following code would be sensible, and if not what are the intended semantics ?. #include <iostream> const char * const GetString(const char * x_in) { static const char * const x = x_in; return x; } int main() { const char * const temp = GetString("yahoo"); std::cout << temp << std::endl; const char * const temp2 = GetString("yahoo2"); std::cout << temp2 << std::endl; } The following compiles on GCC and prints "yahoo" twice. Which is what I want -- However it might not be standards compliant (which is why I post this question). It might be more elegant to have two functions, "SetString" and "String" where the latter forwards to the first. If it is standards compliant does someone know of a templates implementation in boost (or elsewhere) ?

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• Can GPU capabilities impact virtual machine performance?

  - by Dave White

  While this many not seem like a programming question directly, it impacts my development activities and so it seems like it belongs here. It seems that more and more developers are turning to virtual environments for development activities on their computers, SharePoint development being a prime example. Also, as a trainer, I have virtual training environments for all of the classes that I teach. I recently purchased a new Dell E6510 to travel around with. It has the i7 620M (Dual core, HyperThreaded cpu running at 2.66GHz) and 8 GB of memory. Reading the spec sheet, it sounded like it would be a great laptop to carry around and run virtual machines on. Getting the laptop though, I've been pretty disappointed with the user experience of developing in a virtual machine. Giving the Virtual Machine 4 GB of memory, it was slow and I could type complete sentences and watch the VM "catchup". My company has training laptops that we provide for our classes. They are Dell Precision M6400 Intel Core 2 Duo P8700 running at 2.54Ghz with 8 GB of memory and the experience on this laptops is night and day compared to the E6510. They are crisp and you barely aware that you are running in a virtual environment. Since the E6510 should be faster in all categories than the M6400, I couldn't understand why the new laptop was slower, so I did a component by component comparison and the only place where the E6510 is less performant than the M6400 is the graphics department. The M6400 is running a nVidia FX 2700m GPU and the E6510 is running a nVidia 3100M GPU. Looking at benchmarks of the two GPUs suggest that the FX 2700M is twice as fast as the 3100M. http://www.notebookcheck.net/Mobile-Graphics-Cards-Benchmark-List.844.0.html 3100M = 111th (E6510) FX 2700m = 47th (Precision M6400) Radeon HD 5870 = 8th (Alienware) The host OS is Windows 7 64bit as is the guest OS, running in Virtual Box 3.1.8 with Guest Additions installed on the guest. The IDE being used in the virtual environment is VS 2010 Premium. So after that long setup, my question is: Is the GPU significantly impacting the virtual machine's performance or are there other factors that I'm not looking at that I can use to boost the vm's performance? Do we now have to consider GPU performance when purchasing laptops where we expect to use virtualized development environments? Thanks in advance. Cheers, Dave

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• How to learn proper C++?

  - by Chris

  While reading a long series of really, really interesting threads, I've come to a realization: I don't think I really know C++. I know C, I know classes, I know inheritance, I know templates (& the STL) and I know exceptions. Not C++. To clarify, I've been writing "C++" for more than 5 years now. I know C, and I know that C and C++ share a common subset. What I've begun to realize, though, is that more times than not, I wind up treating C++ something vaguely like "C with classes," although I do practice RAII. I've never used Boost, and have only read up on TR1 and C++0x - I haven't used any of these features in practice. I don't use namespaces. I see a list of #defines, and I think - "Gracious, that's horrible! Very un-C++-like," only to go and mindlessly write class wrappers for the sake of it, and I wind up with large numbers (maybe a few per class) of static methods, and for some reason, that just doesn't seem right lately. The professional in me yells "just get the job done," the academic yells "you should write proper C++ when writing C++" and I feel like the point of balance is somewhere in between. I'd like to note that I don't want to program "pure" C++ just for the sake of it. I know several languages. I have a good feel for what "Pythonic" is. I know what clean and clear PHP is. Good C code I can read and write better than English. The issue is that I learned C by example, and picked up C++ as a "series of modifications" to C. And a lot of my early C++ work was creating class wrappers for C libraries. I feel like my own personal C-heavy background while learning C++ has sort of... clouded my acceptance of C++ in it's own right, as it's own language. Do the weathered C++ lags here have any advice for me? Good examples of clean, sharp C++ to learn from? What habits of C does my inner-C++ really need to break from? My goal here is not to go forth and trumpet "good" C++ paradigm from rooftops for the sake of it. C and C++ are two different languages, and I want to start treating them that way. How? Where to start? Thanks in advance! Cheers, -Chris

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• Is it ok to dynamic cast "this" as a return value?

  - by Panayiotis Karabassis

  This is more of a design question. I have a template class, and I want to add extra methods to it depending on the template type. To practice the DRY principle, I have come up with this pattern (definitions intentionally omitted): template <class T> class BaseVector: public boost::array<T, 3> { protected: BaseVector<T>(const T x, const T y, const T z); public: bool operator == (const Vector<T> &other) const; Vector<T> operator + (const Vector<T> &other) const; Vector<T> operator - (const Vector<T> &other) const; Vector<T> &operator += (const Vector<T> &other) { (*this)[0] += other[0]; (*this)[1] += other[1]; (*this)[2] += other[2]; return *dynamic_cast<Vector<T> * const>(this); } } template <class T> class Vector : public BaseVector<T> { public: Vector<T>(const T x, const T y, const T z) : BaseVector<T>(x, y, z) { } }; template <> class Vector<double> : public BaseVector<double> { public: Vector<double>(const double x, const double y, const double z); Vector<double>(const Vector<int> &other); double norm() const; }; I intend BaseVector to be nothing more than an implementation detail. This works, but I am concerned about operator+=. My question is: is the dynamic cast of the this pointer a code smell? Is there a better way to achieve what I am trying to do (avoid code duplication, and unnecessary casts in the user code)? Or am I safe since, the BaseVector constructor is private?

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• Multi-threaded Pooled Allocators

  - by Darren Engwirda

  I'm having some issues using pooled memory allocators for std::list objects in a multi-threaded application. The part of the code I'm concerned with runs each thread function in isolation (i.e. there is no communication or synchronization between threads) and therefore I'd like to setup separate memory pools for each thread, where each pool is not thread-safe (and hence fast). I've tried using a shared thread-safe singleton memory pool and found the performance to be poor, as expected. This is a heavily simplified version of the type of thing I'm trying to do. A lot has been included in a pseudo-code kind of way, sorry if it's confusing. /* The thread functor - one instance of MAKE_QUADTREE created for each thread */ class make_quadtree { private: /* A non-thread-safe memory pool for int linked list items, let's say that it's * something along the lines of BOOST::OBJECT_POOL */ pooled_allocator<int> item_pool; /* The problem! - a local class that would be constructed within each std::list as the * allocator but really just delegates to ITEM_POOL */ class local_alloc { public : //!! I understand that I can't access ITEM_POOL from within a nested class like //!! this, that's really my question - can I get something along these lines to //!! work?? pointer allocate (size_t n) { return ( item_pool.allocate(n) ); } }; public : make_quadtree (): item_pool() // only construct 1 instance of ITEM_POOL per // MAKE_QUADTREE object { /* The kind of data structures - vectors of linked lists * The idea is that all of the linked lists should share a local pooled allocator */ std::vector<std::list<int, local_alloc>> lists; /* The actual operations - too complicated to show, but in general: * * - The vector LISTS is grown as a quadtree is built, it's size is the number of * quadtree "boxes" * * - Each element of LISTS (each linked list) represents the ID's of items * contained within each quadtree box (say they're xy points), as the quadtree * is grown a lot of ID pop/push-ing between lists occurs, hence the memory pool * is important for performance */ } }; So really my problem is that I'd like to have one memory pool instance per thread functor instance, but within each thread functor share the pool between multiple std::list objects.

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• Internet Explorer 8 + Deflate

  - by Andreas Bonini

  I have a very weird problem.. I really do hope someone has an answer because I wouldn't know where else to ask. I am writing a cgi application in C++ which is executed by Apache and outputs HTML code. I am compressing the HTML output myself - from within my C++ application - since my web host doesn't support mod_deflate for some reason. I tested this with Firefox 2, Firefox 3, Opera 9, Opera 10, Google Chrome, Safari, IE6, IE7, IE8, even wget.. It works with ANYTHING except IE8. IE8 just says "Internet Explorer cannot display the webpage", with no information whatsoever. I know it's because of the compression only because it works if I disable it. Do you know what I'm doing wrong? I use zlib to compress it, and the exact code is: /* Compress it */ int compressed_output_size = content.length() + (content.length() * 0.2) + 16; char *compressed_output = (char *)Alloc(compressed_output_size); int compressed_output_length; Compress(compressed_output, compressed_output_size, (void *)content.c_str(), content.length(), &compressed_output_length); /* Send the compressed header */ cout << "Content-Encoding: deflate\r\n"; cout << boost::format("Content-Length: %d\r\n") % compressed_output_length; cgiHeaderContentType("text/html"); cout.write(compressed_output, compressed_output_length); static void Compress(void *to, size_t to_size, void *from, size_t from_size, int *final_size) { int ret; z_stream stream; stream.zalloc = Z_NULL; stream.zfree = Z_NULL; stream.opaque = Z_NULL; if ((ret = deflateInit(&stream, CompressionSpeed)) != Z_OK) COMPRESSION_ERROR("deflateInit() failed: %d", ret); stream.next_out = (Bytef *)to; stream.avail_out = (uInt)to_size; stream.next_in = (Bytef *)from; stream.avail_in = (uInt)from_size; if ((ret = deflate(&stream, Z_NO_FLUSH)) != Z_OK) COMPRESSION_ERROR("deflate() failed: %d", ret); if (stream.avail_in != 0) COMPRESSION_ERROR("stream.avail_in is not 0 (it's %d)", stream.avail_in); if ((ret = deflate(&stream, Z_FINISH)) != Z_STREAM_END) COMPRESSION_ERROR("deflate() failed: %d", ret); if ((ret = deflateEnd(&stream)) != Z_OK) COMPRESSION_ERROR("deflateEnd() failed: %d", ret); if (final_size) *final_size = stream.total_out; return; }

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• Remove never-run call to templated function, get allocation error on run-time

  - by Narfanator

  First off, I'm a bit at a loss as to how to ask this question. So I'm going to try throwing lots of information at the problem. Ok, so, I went to completely redesign my test project for my experimental core library thingy. I use a lot of template shenanigans in the library. When I removed the "user" code, the tests gave me a memory allocation error. After quite a bit of experimenting, I narrowed it down to this bit of code (out of a couple hundred lines): void VOODOO(components::switchBoard &board){ board.addComponent<using_allegro::keyInputs<'w'> >(); } Fundementally, what's weirding me out is that it appears that the act of compiling this function (and the template function it then uses, and the template functions those then use...), makes this bug not appear. This code is not being run. Similar code (the same, but for different key vals) occurs elsewhere, but is within Boost TDD code. I realize I certainly haven't given enough information for you to solve it for me; I tried, but it more-or-less spirals into most of the code base. I think I'm most looking for "here's what the problem could be", "here's where to look", etc. There's something that's happening during compile because of this line, but I don't know enough about that step to begin looking. Sooo, how can a (presumably) compilied, but never actually run, bit of templated code, when removed, cause another part of code to fail? Error: Unhandled exceptionat 0x6fe731ea (msvcr90d.dll) in Switchboard.exe: 0xC0000005: Access violation reading location 0xcdcdcdc1. Callstack: operator delete(void * pUser Data) allocator< class name related to key inputs callbacks ::deallocate vector< same class ::_Insert_n(...) vector< " " ::insert(...) vector<" "::push_back(...) It looks like maybe the vector isn't valid, because _MyFirst and similar data members are showing values of 0xcdcdcdcd in the debugger. But the vector is a member variable...

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• initializing a vector of custom class in c++

  - by Flamewires

  Hey basically Im trying to store a "solution" and create a vector of these. The problem I'm having is with initialization. Heres my class for reference class Solution { private: // boost::thread m_Thread; int itt_found; int dim; pfn_fitness f; double value; std::vector<double> x; public: Solution(size_t size, int funcNo) : itt_found(0), x(size, 0.0), value(0.0), dim(30), f(Eval_Functions[funcNo]) { for (int i = 1; i < (int) size; i++) { x[i] = ((double)rand()/((double)RAND_MAX))*maxs[funcNo]; } } Solution() : itt_found(0), x(31, 0.0), value(0.0), dim(30), f(Eval_Functions[1]) { for (int i = 1; i < 31; i++) { x[i] = ((double)rand()/((double)RAND_MAX))*maxs[1]; } } Solution operator= (Solution S) { x = S.GetX(); itt_found = S.GetIttFound(); dim = S.GetDim(); f = S.GetFunc(); value = S.GetValue(); return *this; } void start() { value = f (dim, x); } /* plus additional getter/setter methods*/ } Solution S(30, 1) or Solution(2, 5) work and initalizes everything, but I need X of these solution objects. std::vector<Solution> Parents(X) will create X solutions with the default constructor and i want to construct using the (int, int) constructor. Is there any easy(one liner?) way to do this? Or would i have to do something like: size_t numparents = 10; vector<Solution> Parents; Parents.reserve(numparents); for (int i = 0; i<(int)numparents; i++) { Solution S(31, 0); Parents.push_back(S); }

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• stxxl Assertion `it != root_node_.end()' failed

  - by Fabrizio Silvestri

  I am receiving this assertion failed error when trying to insert an element in a stxxl map. The entire assertion error is the following: resCache: /usr/include/stxxl/bits/containers/btree/btree.h:470: std::pair , bool stxxl::btree::btree::insert(const value_type&) [with KeyType = e_my_key, DataType = unsigned int, CompareType = comp_type, unsigned int RawNodeSize = 16384u, unsigned int RawLeafSize = 131072u, PDAllocStrategy = stxxl::SR, stxxl::btree::btree::value_type = std::pair]: Assertion `it != root_node_.end()' failed. Aborted Any idea? Edit: Here's the code fragment void request_handler::handle_request(my_key& query, reply& rep) { c_++; strip(query.content); std::cout << "Received query " << query.content << " by thread " << boost::this_thread::get_id() << ". It is number " << c_ << "\n"; strcpy(element.first.content, query.content); element.second = c_; testcache_.insert(element); STXXL_MSG("Records in map: " << testcache_.size()); } Edit2 here's more details (I omit constants, e.g. MAX_QUERY_LEN) struct comp_type : std::binary_function<my_key, my_key, bool> { bool operator () (const my_key & a, const my_key & b) const { return strncmp(a.content, b.content, MAX_QUERY_LEN) < 0; } static my_key max_value() { return max_key; } static my_key min_value() { return min_key; } }; typedef stxxl::map<my_key, my_data, comp_type> cacheType; cacheType testcache_; request_handler::request_handler() :testcache_(NODE_CACHE_SIZE, LEAF_CACHE_SIZE) { c_ = 0; memset(max_key.content, (std::numeric_limits<unsigned char>::max)(), MAX_QUERY_LEN); memset(min_key.content, (std::numeric_limits<unsigned char>::min)(), MAX_QUERY_LEN); testcache_.enable_prefetching(); STXXL_MSG("Records in map: " << testcache_.size()); }

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• How to approach copying objects with smart pointers as class attributes?

  - by tomislav-maric

  From the boost library documentation I read this: Conceptually, smart pointers are seen as owning the object pointed to, and thus responsible for deletion of the object when it is no longer needed. I have a very simple problem: I want to use RAII for pointer attributes of a class that is Copyable and Assignable. The copy and assignment operations should be deep: every object should have its own copy of the actual data. Also, RTTI needs to be available for the attributes (their type may also be determined at runtime). Should I be searching for an implementation of a Copyable smart pointer (the data are small, so I don't need Copy on Write pointers), or do I delegate the copy operation to the copy constructors of my objects as shown in this answer? Which smart pointer do I choose for simple RAII of a class that is copyable and assignable? (I'm thinking that the unique_ptr with delegated copy/assignment operations to the class copy constructor and assignment operator would make a proper choice, but I am not sure) Here's a pseudocode for the problem using raw pointers, it's just a problem description, not a running C++ code: // Operation interface class ModelOperation { public: virtual void operate = (); }; // Implementation of an operation called Special class SpecialModelOperation : public ModelOperation { private: // Private attributes are present here in a real implementation. public: // Implement operation void operate () {}; }; // All operations conform to ModelOperation interface // These are possible operation names: // class MoreSpecialOperation; // class DifferentOperation; // Concrete model with different operations class MyModel { private: ModelOperation* firstOperation_; ModelOperation* secondOperation_; public: MyModel() : firstOperation_(0), secondOperation_(0) { // Forgetting about run-time type definition from input files here. firstOperation_ = new MoreSpecialOperation(); secondOperation_ = new DifferentOperation(); } void operate() { firstOperation_->operate(); secondOperation_->operate(); } ~MyModel() { delete firstOperation_; firstOperation_ = 0; delete secondOperation_; secondOperation_ = 0; } }; int main() { MyModel modelOne; // Some internal scope { // I want modelTwo to have its own set of copied, not referenced // operations, and at the same time I need RAII to work for it, // as soon as it goes out of scope. MyModel modelTwo (modelOne); } return 0; }

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• Detect if class has overloaded function fails on Comeau compiler

  - by Frank

  Hi Everyone, I'm trying to use SFINAE to detect if a class has an overloaded member function that takes a certain type. The code I have seems to work correctly in Visual Studio and GCC, but does not compile using the Comeau online compiler. Here is the code I'm using: #include <stdio.h> //Comeau doesnt' have boost, so define our own enable_if_c template<bool value> struct enable_if_c { typedef void type; }; template<> struct enable_if_c< false > {}; //Class that has the overloaded member function class TestClass { public: void Func(float value) { printf( "%f\n", value ); } void Func(int value) { printf( "%i\n", value ); } }; //Struct to detect if TestClass has an overloaded member function for type T template<typename T> struct HasFunc { template<typename U, void (TestClass::*)( U )> struct SFINAE {}; template<typename U> static char Test(SFINAE<U, &TestClass::Func>*); template<typename U> static int Test(...); static const bool Has = sizeof(Test<T>(0)) == sizeof(char); }; //Use enable_if_c to only allow the function call if TestClass has a valid overload for T template<typename T> typename enable_if_c<HasFunc<T>::Has>::type CallFunc(TestClass &test, T value) { test.Func( value ); } int main() { float value1 = 0.0f; int value2 = 0; TestClass testClass; CallFunc( testClass, value1 ); //Should call TestClass::Func( float ) CallFunc( testClass, value2 ); //Should call TestClass::Func( int ) } The error message is: no instance of function template "CallFunc" matches the argument list. It seems that HasFunc::Has is false for int and float when it should be true. Is this a bug in the Comeau compiler? Am I doing something that's not standard? And if so, what do I need to do to fix it?

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• Xobni Free Powers Up Outlook’s Search and Contacts

  - by Matthew Guay

  Want to find out more about your contacts, discover email trends, and even sync Yahoo! email accounts in Outlook?  Here’s how you can do this and more with Xobni Free. Email is one of the most important communications mediums today, but even with all of the advances in Outlook over the years it can still be difficult to keep track of conversations, files, and contacts.  Xobni makes it easy by indexing your emails and organizing them by sender.  You can use its powerful search to quickly find any email, find related messages, and then view more information about that contact with information from social networks.  And, to top it off, it even lets you view your Yahoo! emails directly in Outlook without upgrading to a Yahoo! Plus account.  Xobni runs in Outlook 2003, 2007, and 2010, including the 64 bit version of Outlook 2010, and users of older versions will especially enjoy the new features Xobni brings for free. Getting started Download the Xobni Free installer (link below), and run to start the installation.  Make sure to exit Outlook before installing.  Xobni may need to download additional files which may take a few moments. When the download is finished, proceed with the install as normal.  You can opt out of the Product Improvement Program at the end of the installation by unchecking the box.  Additionally, you are asked to share Xobni with your friends on social networks, but this is not required.   Next time you open Outlook, you’ll notice the new Xobni sidebar in Outlook.  You can choose to watch an introduction video that will help you quickly get up to speed on how Xobni works. While this is playing, Xobni is working at indexing your email in the background.  Once the first indexing is finished, click Let’s Go! to start using Xobni. Here’s how Xobni looks in Outlook 2010: Advanced Email Information Select an email, and now you can see lots of info about it in your new Xobni sidebar.   On the top of the sidebar, select the graph icon to see when and how often you email with a contact.  Each contact is given an Xobni rank so you can quickly see who you email the most.   You can see all related emails sorted into conversations, and also all attachments in the conversation, not just this email. Xobni can also show you all scheduled appointments and links exchanged with a contact, but this is only available in the Plus version.  If you’d rather not see the tab for a feature you can’t use, click Don’t show this tab to banish it from Xobni for good.   Searching emails from the Xobni toolbar is very fast, and you can preview a message by simply hovering over it from the search pane. Get More Information About Your Contacts Xobni’s coolest feature is its social integration.  Whenever you select an email, you may see a brief bio, picture, and more, all pulled from social networks.   Select one of the tabs to find more information.  You may need to login to view information on your contacts from certain networks. The Twitter tab lets you see recent tweets.  Xobni will search for related Twitter accounts, and will ask you to confirm if the choice is correct.   Now you can see this contact’s recent Tweets directly from Outlook.   The Hoovers tab can give you interesting information about the businesses you’re in contact with. If the information isn’t correct, you can edit it and add your own information.  Click the Edit button, and the add any information you want.   You can also remove a network you don’t wish to see.  Right-click on the network tabs, select Manage Extensions, and uncheck any you don’t want to see. But sometimes online contact just doesn’t cut it.  For these times, click on the orange folder button to request a contact’s phone number or schedule a time with them. This will open a new email message ready to send with the information you want.  Edit as you please, and send. Add Yahoo! Email to Outlook for Free One of Xobni’s neatest features is that it let’s you add your Yahoo! email account to Outlook for free.  Click the gear icon in the bottom of the Xobni sidebar and select Options to set it up. Select the Integration tab, and click Enable to add Yahoo! mail to Xobni. Sign in with your Yahoo! account, and make sure to check the Keep me signed in box. Note that you may have to re-signin every two weeks to keep your Yahoo! account connected.  Select I agree to finish setting it up. Xobni will now download and index your recent Yahoo! mail. Your Yahoo! messages will only show up in the Xobni sidebar.  Whenever you select a contact, you will see related messages from your Yahoo! account as well.  Or, you can search from the sidebar to find individual messages from your Yahoo! account.  Note the Y! logo beside Yahoo! messages.   Select a message to read it in the Sidebar.  You can open the email in Yahoo! in your browser, or can reply to it using your default Outlook email account. If you have many older messages in your Yahoo! account, make sure to go back to the Integration tab and select Index Yahoo! Mail to index all of your emails. Conclusion Xobni is a great tool to help you get more out of your daily Outlook experience.  Whether you struggle to find attachments a coworker sent you or want to access Yahoo! email from Outlook, Xobni might be the perfect tool for you.  And with the extra things you learn about your contacts with the social network integration, you might boost your own PR skills without even trying! Link Download Xobni Similar Articles Productive Geek Tips Speed up Windows Vista Start Menu Search By Limiting ResultsFix for New Contact Group Button Not Displaying in VistaGet Maps and Directions to Your Contacts in Outlook 2007Backup Windows Mail Messages and Contacts in VistaHow to Import Gmail Contacts Into Outlook 2007 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Acronis Online Backup DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows iFixit Offers Gadget Repair Manuals Online Vista style sidebar for Windows 7 Create Nice Charts With These Web Based Tools Track Daily Goals With 42Goals Video Toolbox is a Superb Online Video Editor Fun with 47 charts and graphs

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• Why can't I build Deluge?

  - by hugemeow

  Deluge is a BitTorrent Client. I am trying to build it from source, since I don't have privilege to install it as root. I am using python setup.py build. But, it failed following message, why? copying deluge/ui/web/themes/images/gray/slider/slider-v-thumb.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/gray/slider copying deluge/ui/web/themes/images/gray/slider/slider-thumb.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/gray/slider copying deluge/ui/web/themes/images/gray/panel/top-bottom.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/gray/panel copying deluge/ui/web/themes/images/gray/tabs/tab-strip-bg.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/gray/tabs copying deluge/ui/web/themes/images/yourtheme/window/right-corners.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/window copying deluge/ui/web/themes/images/yourtheme/window/left-corners.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/window copying deluge/ui/web/themes/images/yourtheme/window/left-right.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/window copying deluge/ui/web/themes/images/yourtheme/window/top-bottom.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/window creating build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/slider copying deluge/ui/web/themes/images/yourtheme/slider/slider-v-thumb.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/slider copying deluge/ui/web/themes/images/yourtheme/slider/slider-thumb.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/slider copying deluge/ui/web/themes/images/yourtheme/slider/slider-bg.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/slider copying deluge/ui/web/themes/images/yourtheme/slider/slider-v-bg.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/slider copying deluge/ui/web/themes/images/yourtheme/panel/top-bottom.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/panel copying deluge/ui/web/themes/images/yourtheme/grid/hmenu-lock.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/grid copying deluge/ui/web/themes/images/yourtheme/grid/hmenu-unlock.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/grid copying deluge/ui/web/themes/images/yourtheme/tabs/tab-strip-bg.png -> build/lib.linux-x86_64-2.4/deluge/ui/web/themes/images/yourtheme/tabs running build_ext building 'libtorrent' extension gcc -pthread -shared -L/usr/lib64 -L/opt/local/lib -lboost_filesystem -lboost_date_time -lboost_iostreams -lboost_python -lboost_thread -lpthread -lssl -lz -o build/lib.linux-x86_64-2.4/deluge/libtorrent.so /usr/bin/ld: cannot find -lboost_filesystem collect2: ld returned 1 exit status error: command 'gcc' failed with exit status 1 [mirror@innov deluge-1.3.5]$ echo $? 1 Edit 1: gcc version and os information $(which gcc) --version gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-52) Copyright (C) 2006 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. cat /etc/issue CentOS release 5.7 (Final) Kernel \r on an \m Edit 2: boost is referenced by setup.py in deluge 114 if OS == "linux": 115 if os.path.exists(os.path.join(sysconfig.get_config_vars()['LIBDIR'], \ 116 'libboost_filesystem-mt.so')): 117 boost_filesystem = "boost_filesystem-mt" 118 elif os.path.exists(os.path.join(sysconfig.get_config_vars()['LIBDIR'], \ 119 'libboost_filesystem.so')): 120 boost_filesystem = "boost_filesystem" 121 if os.path.exists(os.path.join(sysconfig.get_config_vars()['LIBDIR'], \ 122 'libboost_date_time-mt.so')): 123 boost_date_time = "boost_date_time-mt" 124 elif os.path.exists(os.path.join(sysconfig.get_config_vars()['LIBDIR'], \ 125 'libboost_date_time.so')): 126 boost_date_time = "boost_date_time" 127 if os.path.exists(os.path.join(sysconfig.get_config_vars()['LIBDIR'], \ 128 'libboost_thread-mt.so')): 129 boost_thread = "boost_thread-mt" 130 elif os.path.exists(os.path.join(sysconfig.get_config_vars()['LIBDIR'], \ 131 'libboost_thread.so')): 132 boost_thread = "boost_thread" 133 134 if 'boost_filesystem' not in vars(): 135 boost_filesystem = "boost_filesystem-mt" 136 if 'boost_date_time' not in vars(): 137 boost_date_time = "boost_date_time-mt" 138 if 'boost_thread' not in vars(): 139 boost_thread = "boost_thread-mt" 140 141 elif OS == "freebsd": 142 boost_filesystem = "boost_filesystem" 143 boost_date_time = "boost_date_time" 144 boost_thread = "boost_thread" 145 else: 146 boost_filesystem = "boost_filesystem-mt" 147 boost_date_time = "boost_date_time-mt" 148 boost_thread = "boost_thread-mt" 149 150 librariestype = [boost_filesystem, boost_date_time, 151 boost_thread, 'z', 'pthread', 'ssl', 'crypto']

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• Why It Is So Important to Know Your Customer

  - by Christie Flanagan

  Over the years, I endured enough delayed flights, air turbulence and misadventures in airport security clearance to watch my expectations for the air travel experience fall to abysmally low levels. The extent of my loyalty to any one carrier had more to do with the proximity of the airport parking garage to their particular gate than to any effort on the airline’s part to actually earn and retain my business. That all changed one day when I found myself at the airport hoping to catch a return flight home a few hours earlier than expected, using an airline I had flown with for the first time just that week.  When you travel regularly for business, being able to catch a return flight home that’s even an hour or two earlier than originally scheduled is a big deal. It can mean the difference between having a normal evening with your family and having to sneak in like a cat burglar after everyone is fast asleep. And so I found myself on this particular day hoping to catch an earlier flight home. I approached the gate agent and was told that I could go on standby for their next flight out. Then I asked how much it was going to cost to change the flight, knowing full well that I wouldn’t get reimbursed by my company for any change fees. “Oh, there’s no charge to fly on standby,” the gate agent told me. I made a funny look. I couldn’t believe what I was hearing. This airline was going to let my fly on standby, at no additional charge, even though I was a new customer with no status or points. It had been years since I’d seen an airline pass up a short term revenue generating opportunity in favor of a long term loyalty generating one.  At that moment, this particular airline gained my loyal business. Since then, this airline has had the opportunity to learn a lot about me. They know where I live, where I fly from, where I usually fly to, and where I like to sit on the plane. In general, I’ve found their customer service to be quite good whether at the airport, via call center and even through social channels. They email me occasionally, and when they do, they demonstrate that they know me by promoting deals for flights from where I live to places that I’d be interested in visiting. And that’s part of why I’m always so puzzled when I visit their website.Does this company with the great service, customer friendly policies, and clean planes demonstrate that they know me at all when I visit their website? The answer is no. Even when I log in using my loyalty program credentials, it’s pretty obvious that they’re presenting the same old home page and same old offers to every single one of their site visitors. I mean, those promotional offers that they’re featuring so prominently  -- they’re for flights that originate thousands of miles from where I live! There’s no way I’d ever book one of those flights and I’m sure I’m not the only one of their customers to feel that way.My reason for recounting this story is not to pick on the one customer experience flaw I've noticed with this particular airline, in fact, they do so many things right that I’ll continue to fly with them. But I did want to illustrate just how glaringly obvious it is to customers today when a touch point they have with a brand is impersonal, unconnected and out of sync. As someone who’s spent a number of years in the web experience management and online marketing space, it particularly peeves me when that out of sync touch point is a brand’s website, perhaps because I know how important it is to make a customer’s online experience relevant and how many powerful tools are available for making a relevant experience a reality. The fact is, delivering a one-size-fits-all online customer experience is no longer acceptable or particularly effective in today’s world. Today’s savvy customers expect you to know who they are and to understand their preferences, behavior and relationship with your brand. Not only do they expect you to know about them, but they also expect you to demonstrate this knowledge across all of their touch points with your brand in a consistent and compelling fashion, whether it be on your traditional website, your mobile web presence or through various social channels.Delivering the kind of personalized online experiences that customers want can have tremendous business benefits. This is not just about generating feelings of goodwill and higher customer satisfaction ratings either. More relevant and personalized online experiences boost the effectiveness of online marketing initiatives and the statistics prove this out. Personalized web experiences can help increase online conversion rates by 70% -- that’s a huge number.1  And more than three quarters of consumers indicate that they’ve made additional online purchases based on personalized product recommendations.2Now if only this airline would get on board with delivering a more personalized online customer experience. I’d certainly be happier and more likely to spring for one of their promotional offers. And by targeting relevant offers on their home page to appropriate segments of their site visitors, I bet they’d be happier and generating additional revenue too. Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}  ***** If you're interested in hearing more perspectives on the benefits of demonstrating that you know your customers by delivering a more personalized experience, check out this white paper on creating a successful and meaningful customer experience on the web.  Also catch the video below on the business value of CX in attracting new customers featuring Oracle's VP of Customer Experience Strategy, Brian Curran. 1 Search Engine Watch 2 Marketing Charts

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• Static background noise while using new headset Ubuntu 13.04

  - by ThundLayr

  Today I bought a new gaming headset (Gx-Gaming Lychas), and when I tried to record some gameplay-comentary I noticed that there always is a static background noise, I just recorded an example so you guys can listen it (no downloaded needed): http://www47.zippyshare.com/v/65167832/file.html I'm using Kubuntu 13.04 and Kernel version is 3.8.0-19, my laptop is an Acer Travelmate 5760Z, I tried tons of configurations on Alsamixer and none of them made result, I really need to get this working so any kind of help will be very aprecciated. cat /proc/asound/cards: 0 [PCH ]: HDA-Intel - HDA Intel PCH HDA Intel PCH at 0xc6400000 irq 44 cat /proc/asound/card0/codec#0 Codec: Conexant CX20588 Address: 0 AFG Function Id: 0x1 (unsol 1) Vendor Id: 0x14f1506c Subsystem Id: 0x10250574 Revision Id: 0x100003 No Modem Function Group found Default PCM: rates [0x160]: 44100 48000 96000 bits [0xe]: 16 20 24 formats [0x1]: PCM Default Amp-In caps: N/A Default Amp-Out caps: N/A State of AFG node 0x01: Power states: D0 D1 D2 D3 D3cold CLKSTOP EPSS Power: setting=D0, actual=D0 GPIO: io=4, o=0, i=0, unsolicited=1, wake=0 IO[0]: enable=0, dir=0, wake=0, sticky=0, data=0, unsol=0 IO[1]: enable=0, dir=0, wake=0, sticky=0, data=0, unsol=0 IO[2]: enable=0, dir=0, wake=0, sticky=0, data=0, unsol=0 IO[3]: enable=0, dir=0, wake=0, sticky=0, data=0, unsol=0 Node 0x10 [Audio Output] wcaps 0xc1d: Stereo Amp-Out R/L Control: name="Headphone Playback Volume", index=0, device=0 ControlAmp: chs=3, dir=Out, idx=0, ofs=0 Control: name="Headphone Playback Switch", index=0, device=0 ControlAmp: chs=3, dir=Out, idx=0, ofs=0 Device: name="CX20588 Analog", type="Audio", device=0 Amp-Out caps: ofs=0x4a, nsteps=0x4a, stepsize=0x03, mute=1 Amp-Out vals: [0x4a 0x4a] Converter: stream=8, channel=0 PCM: rates [0x560]: 44100 48000 96000 192000 bits [0xe]: 16 20 24 formats [0x1]: PCM Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Node 0x11 [Audio Output] wcaps 0xc1d: Stereo Amp-Out R/L Control: name="Speaker Playback Volume", index=0, device=0 ControlAmp: chs=3, dir=Out, idx=0, ofs=0 Control: name="Speaker Playback Switch", index=0, device=0 ControlAmp: chs=3, dir=Out, idx=0, ofs=0 Amp-Out caps: ofs=0x4a, nsteps=0x4a, stepsize=0x03, mute=1 Amp-Out vals: [0x80 0x80] Converter: stream=8, channel=0 PCM: rates [0x560]: 44100 48000 96000 192000 bits [0xe]: 16 20 24 formats [0x1]: PCM Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Node 0x12 [Audio Output] wcaps 0x611: Stereo Digital Converter: stream=0, channel=0 Digital: Digital category: 0x0 IEC Coding Type: 0x0 PCM: rates [0x160]: 44100 48000 96000 bits [0xe]: 16 20 24 formats [0x5]: PCM AC3 Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Node 0x13 [Beep Generator Widget] wcaps 0x70000c: Mono Amp-Out Control: name="Beep Playback Volume", index=0, device=0 ControlAmp: chs=1, dir=Out, idx=0, ofs=0 Control: name="Beep Playback Switch", index=0, device=0 ControlAmp: chs=1, dir=Out, idx=0, ofs=0 Amp-Out caps: ofs=0x07, nsteps=0x07, stepsize=0x0f, mute=0 Amp-Out vals: [0x00] Node 0x14 [Audio Input] wcaps 0x100d1b: Stereo Amp-In R/L Control: name="Capture Volume", index=0, device=0 ControlAmp: chs=3, dir=In, idx=0, ofs=0 Control: name="Capture Switch", index=0, device=0 ControlAmp: chs=3, dir=In, idx=0, ofs=0 Device: name="CX20588 Analog", type="Audio", device=0 Amp-In caps: ofs=0x4a, nsteps=0x50, stepsize=0x03, mute=1 Amp-In vals: [0x50 0x50] [0x80 0x80] [0x80 0x80] [0x80 0x80] Converter: stream=4, channel=0 SDI-Select: 0 PCM: rates [0x160]: 44100 48000 96000 bits [0xe]: 16 20 24 formats [0x1]: PCM Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 4 0x17* 0x18 0x23 0x24 Node 0x15 [Audio Input] wcaps 0x100d1b: Stereo Amp-In R/L Amp-In caps: ofs=0x4a, nsteps=0x50, stepsize=0x03, mute=1 Amp-In vals: [0x4a 0x4a] [0x4a 0x4a] [0x4a 0x4a] [0x4a 0x4a] Converter: stream=0, channel=0 SDI-Select: 0 PCM: rates [0x160]: 44100 48000 96000 bits [0xe]: 16 20 24 formats [0x1]: PCM Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 4 0x17* 0x18 0x23 0x24 Node 0x16 [Audio Input] wcaps 0x100d1b: Stereo Amp-In R/L Amp-In caps: ofs=0x4a, nsteps=0x50, stepsize=0x03, mute=1 Amp-In vals: [0x4a 0x4a] [0x4a 0x4a] [0x4a 0x4a] [0x4a 0x4a] Converter: stream=0, channel=0 SDI-Select: 0 PCM: rates [0x160]: 44100 48000 96000 bits [0xe]: 16 20 24 formats [0x1]: PCM Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 4 0x17* 0x18 0x23 0x24 Node 0x17 [Audio Selector] wcaps 0x30050d: Stereo Amp-Out Control: name="Mic Boost Volume", index=0, device=0 ControlAmp: chs=3, dir=Out, idx=0, ofs=0 Amp-Out caps: ofs=0x00, nsteps=0x04, stepsize=0x27, mute=0 Amp-Out vals: [0x04 0x04] Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 4 0x1a 0x1b* 0x1d 0x1e Node 0x18 [Audio Selector] wcaps 0x30050d: Stereo Amp-Out Amp-Out caps: ofs=0x00, nsteps=0x04, stepsize=0x27, mute=0 Amp-Out vals: [0x00 0x00] Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 4 0x1a* 0x1b 0x1d 0x1e Node 0x19 [Pin Complex] wcaps 0x400581: Stereo Control: name="Headphone Jack", index=0, device=0 Pincap 0x0000001c: OUT HP Detect Pin Default 0x04214040: [Jack] HP Out at Ext Right Conn = 1/8, Color = Green DefAssociation = 0x4, Sequence = 0x0 Pin-ctls: 0xc0: OUT HP Unsolicited: tag=01, enabled=1 Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 2 0x10* 0x11 Node 0x1a [Pin Complex] wcaps 0x400481: Stereo Control: name="Internal Mic Phantom Jack", index=0, device=0 Pincap 0x00001324: IN Detect Vref caps: HIZ 50 80 Pin Default 0x90a70130: [Fixed] Mic at Int N/A Conn = Analog, Color = Unknown DefAssociation = 0x3, Sequence = 0x0 Misc = NO_PRESENCE Pin-ctls: 0x24: IN VREF_80 Unsolicited: tag=00, enabled=0 Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Node 0x1b [Pin Complex] wcaps 0x400581: Stereo Control: name="Mic Jack", index=0, device=0 Pincap 0x00011334: IN OUT EAPD Detect Vref caps: HIZ 50 80 EAPD 0x0: Pin Default 0x04a19020: [Jack] Mic at Ext Right Conn = 1/8, Color = Pink DefAssociation = 0x2, Sequence = 0x0 Pin-ctls: 0x24: IN VREF_80 Unsolicited: tag=02, enabled=1 Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 2 0x10* 0x11 Node 0x1c [Pin Complex] wcaps 0x400581: Stereo Pincap 0x00000014: OUT Detect Pin Default 0x40f001f0: [N/A] Other at Ext N/A Conn = Unknown, Color = Unknown DefAssociation = 0xf, Sequence = 0x0 Misc = NO_PRESENCE Pin-ctls: 0x40: OUT Unsolicited: tag=00, enabled=0 Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 2 0x10* 0x11 Node 0x1d [Pin Complex] wcaps 0x400581: Stereo Pincap 0x00010034: IN OUT EAPD Detect EAPD 0x0: Pin Default 0x40f001f0: [N/A] Other at Ext N/A Conn = Unknown, Color = Unknown DefAssociation = 0xf, Sequence = 0x0 Misc = NO_PRESENCE Pin-ctls: 0x40: OUT Unsolicited: tag=00, enabled=0 Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 2 0x10* 0x11 Node 0x1e [Pin Complex] wcaps 0x400481: Stereo Pincap 0x00000024: IN Detect Pin Default 0x40f001f0: [N/A] Other at Ext N/A Conn = Unknown, Color = Unknown DefAssociation = 0xf, Sequence = 0x0 Misc = NO_PRESENCE Pin-ctls: 0x00: Unsolicited: tag=00, enabled=0 Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Node 0x1f [Pin Complex] wcaps 0x400501: Stereo Control: name="Speaker Phantom Jack", index=0, device=0 Pincap 0x00000010: OUT Pin Default 0x92170110: [Fixed] Speaker at Int Front Conn = Analog, Color = Unknown DefAssociation = 0x1, Sequence = 0x0 Misc = NO_PRESENCE Pin-ctls: 0x40: OUT Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 2 0x10 0x11* Node 0x20 [Pin Complex] wcaps 0x400781: Stereo Digital Pincap 0x00000010: OUT Pin Default 0x40f001f0: [N/A] Other at Ext N/A Conn = Unknown, Color = Unknown DefAssociation = 0xf, Sequence = 0x0 Misc = NO_PRESENCE Pin-ctls: 0x00: Unsolicited: tag=00, enabled=0 Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 1 0x12 Node 0x21 [Audio Output] wcaps 0x611: Stereo Digital Converter: stream=0, channel=0 Digital: Digital category: 0x0 IEC Coding Type: 0x0 PCM: rates [0x160]: 44100 48000 96000 bits [0xe]: 16 20 24 formats [0x5]: PCM AC3 Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Node 0x22 [Pin Complex] wcaps 0x400781: Stereo Digital Pincap 0x00000010: OUT Pin Default 0x40f001f0: [N/A] Other at Ext N/A Conn = Unknown, Color = Unknown DefAssociation = 0xf, Sequence = 0x0 Misc = NO_PRESENCE Pin-ctls: 0x00: Unsolicited: tag=00, enabled=0 Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 1 0x21 Node 0x23 [Pin Complex] wcaps 0x40040b: Stereo Amp-In Amp-In caps: ofs=0x00, nsteps=0x04, stepsize=0x2f, mute=0 Amp-In vals: [0x00 0x00] Pincap 0x00000020: IN Pin Default 0x40f001f0: [N/A] Other at Ext N/A Conn = Unknown, Color = Unknown DefAssociation = 0xf, Sequence = 0x0 Misc = NO_PRESENCE Pin-ctls: 0x00: Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Node 0x24 [Audio Mixer] wcaps 0x20050b: Stereo Amp-In Amp-In caps: ofs=0x4a, nsteps=0x4a, stepsize=0x03, mute=1 Amp-In vals: [0x00 0x00] [0x00 0x00] Power states: D0 D1 D2 D3 D3cold EPSS Power: setting=D0, actual=D0 Connection: 2 0x10 0x11 Node 0x25 [Vendor Defined Widget] wcaps 0xf00000: Mono

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• Have I pushed the limits of my current VPS or is there room for optimization?

  - by JRameau

  I am currently on a mediatemple DV server (basic) 512mb dedicated ram, this is a CentOS based VPS with Plesk and Virtuozzo. My experience with it from day 1 has been bad and I only could sooth my server issues with several caching "Band-aids," but my sites are not as small as they were a year ago either so the issues have worsen. I have 3 Drupal installs running on separate (plesk) domains, 1 of those drupal installs is a multisite, that consists of 5-6 sites 2 of those sites are bringing in actual traffic. Those caching "Band-aids" I mentioned are APC, which seemed to help alot initially, and Drupal's Boost, which is considered a poorman's Varnish, it makes all my pages static for anonymous users. Last 30day combined estimate on Google Ananlytics: 90k visitors 260k pageviews. Issue: alot of downtime, I am continually checking if my sites are up, and lately I have been finding it down more than 3 times daily. Restarting Apache will bring it back up, for some time. I have google search every error message and looked up ways to optimize my DV server, and I am beyond stump what is my next move. Is this server bad, have I hit a impossibly low restriction such as the 12mb kernel memory barrier (kmemsize), is it on my end, do I need to optimize some more? *I have provided as much information as I can below, any help or suggestions given will be appreciated Common Error messages I see in the log: [error] (12)Cannot allocate memory: fork: Unable to fork new process [error] make_obcallback: could not import mod_python.apache.\n Traceback (most recent call last): File "/usr/lib/python2.4/site-packages/mod_python/apache.py", line 21, in ? import traceback File "/usr/lib/python2.4/traceback.py", line 3, in ? import linecache ImportError: No module named linecache [error] python_handler: no interpreter callback found. [warn-phpd] mmap cache can't open /var/www/vhosts/***/httpdocs/*** - Too many open files in system (pid ***) [alert] Child 8125 returned a Fatal error... Apache is exiting! [emerg] (43)Identifier removed: couldn't grab the accept mutex [emerg] (22)Invalid argument: couldn't release the accept mutex cat /proc/user_beancounters: Version: 2.5 uid resource held maxheld barrier limit failcnt 41548: kmemsize 4582652 5306699 12288832 13517715 21105036 lockedpages 0 0 600 600 0 privvmpages 38151 42676 229036 249036 0 shmpages 16274 16274 17237 17237 2 dummy 0 0 0 0 0 numproc 43 46 300 300 0 physpages 27260 29528 0 2147483647 0 vmguarpages 0 0 131072 2147483647 0 oomguarpages 27270 29538 131072 2147483647 0 numtcpsock 21 29 300 300 0 numflock 8 8 480 528 0 numpty 1 1 30 30 0 numsiginfo 0 1 1024 1024 0 tcpsndbuf 648440 675272 2867477 4096277 1711499 tcprcvbuf 301620 359716 2867477 4096277 0 othersockbuf 4472 4472 1433738 2662538 0 dgramrcvbuf 0 0 1433738 1433738 0 numothersock 12 12 300 300 0 dcachesize 0 0 2684271 2764800 0 numfile 3447 3496 6300 6300 3872 dummy 0 0 0 0 0 dummy 0 0 0 0 0 dummy 0 0 0 0 0 numiptent 14 14 200 200 0 TOP: (In January the load avg was really high 3-10, I was able to bring it down where it is currently is by giving APC more memory play around with) top - 16:46:07 up 2:13, 1 user, load average: 0.34, 0.20, 0.20 Tasks: 40 total, 2 running, 37 sleeping, 0 stopped, 1 zombie Cpu(s): 0.3% us, 0.1% sy, 0.0% ni, 99.7% id, 0.0% wa, 0.0% hi, 0.0% si Mem: 916144k total, 156668k used, 759476k free, 0k buffers Swap: 0k total, 0k used, 0k free, 0k cached MySQLTuner: (after optimizing every table and repairing any table with overage I got the fragmented count down to 86) [--] Data in MyISAM tables: 285M (Tables: 1105) [!!] Total fragmented tables: 86 [--] Up for: 2h 44m 38s (409K q [41.421 qps], 6K conn, TX: 1B, RX: 174M) [--] Reads / Writes: 79% / 21% [--] Total buffers: 58.0M global + 2.7M per thread (100 max threads) [!!] Query cache prunes per day: 675307 [!!] Temporary tables created on disk: 35% (7K on disk / 20K total)

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• Using Node.js as an accelerator for WCF REST services

  - by Elton Stoneman

  Node.js is a server-side JavaScript platform "for easily building fast, scalable network applications". It's built on Google's V8 JavaScript engine and uses an (almost) entirely async event-driven processing model, running in a single thread. If you're new to Node and your reaction is "why would I want to run JavaScript on the server side?", this is the headline answer: in 150 lines of JavaScript you can build a Node.js app which works as an accelerator for WCF REST services*. It can double your messages-per-second throughput, halve your CPU workload and use one-fifth of the memory footprint, compared to the WCF services direct.   Well, it can if: 1) your WCF services are first-class HTTP citizens, honouring client cache ETag headers in request and response; 2) your services do a reasonable amount of work to build a response; 3) your data is read more often than it's written. In one of my projects I have a set of REST services in WCF which deal with data that only gets updated weekly, but which can be read hundreds of times an hour. The services issue ETags and will return a 304 if the client sends a request with the current ETag, which means in the most common scenario the client uses its local cached copy. But when the weekly update happens, then all the client caches are invalidated and they all need the same new data. Then the service will get hundreds of requests with old ETags, and they go through the full service stack to build the same response for each, taking up threads and processing time. Part of that processing means going off to a database on a separate cloud, which introduces more latency and downtime potential.   We can use ASP.NET output caching with WCF to solve the repeated processing problem, but the server will still be thread-bound on incoming requests, and to get the current ETags reliably needs a database call per request. The accelerator solves that by running as a proxy - all client calls come into the proxy, and the proxy routes calls to the underlying REST service. We could use Node as a straight passthrough proxy and expect some benefit, as the server would be less thread-bound, but we would still have one WCF and one database call per proxy call. But add some smart caching logic to the proxy, and share ETags between Node and WCF (so the proxy doesn't even need to call the servcie to get the current ETag), and the underlying service will only be invoked when data has changed, and then only once - all subsequent client requests will be served from the proxy cache.   I've built this as a sample up on GitHub: NodeWcfAccelerator on sixeyed.codegallery. Here's how the architecture looks:     The code is very simple. The Node proxy runs on port 8010 and all client requests target the proxy. If the client request has an ETag header then the proxy looks up the ETag in the tag cache to see if it is current - the sample uses memcached to share ETags between .NET and Node. If the ETag from the client matches the current server tag, the proxy sends a 304 response with an empty body to the client, telling it to use its own cached version of the data. If the ETag from the client is stale, the proxy looks for a local cached version of the response, checking for a file named after the current ETag. If that file exists, its contents are returned to the client as the body in a 200 response, which includes the current ETag in the header. If the proxy does not have a local cached file for the service response, it calls the service, and writes the WCF response to the local cache file, and to the body of a 200 response for the client. So the WCF service is only troubled if both client and proxy have stale (or no) caches.   The only (vaguely) clever bit in the sample is using the ETag cache, so the proxy can serve cached requests without any communication with the underlying service, which it does completely generically, so the proxy has no notion of what it is serving or what the services it proxies are doing. The relative path from the URL is used as the lookup key, so there's no shared key-generation logic between .NET and Node, and when WCF stores a tag it also stores the "read" URL against the ETag so it can be used for a reverse lookup, e.g:   Key Value /WcfSampleService/PersonService.svc/rest/fetch/3 "28cd4796-76b8-451b-adfd-75cb50a50fa6" "28cd4796-76b8-451b-adfd-75cb50a50fa6" /WcfSampleService/PersonService.svc/rest/fetch/3    In Node we read the cache using the incoming URL path as the key and we know that "28cd4796-76b8-451b-adfd-75cb50a50fa6" is the current ETag; we look for a local cached response in /caches/28cd4796-76b8-451b-adfd-75cb50a50fa6.body (and the corresponding .header file which contains the original service response headers, so the proxy response is exactly the same as the underlying service). When the data is updated, we need to invalidate the ETag cache – which is why we need the reverse lookup in the cache. In the WCF update service, we don't need to know the URL of the related read service - we fetch the entity from the database, do a reverse lookup on the tag cache using the old ETag to get the read URL, update the new ETag against the URL, store the new reverse lookup and delete the old one.   Running Apache Bench against the two endpoints gives the headline performance comparison. Making 1000 requests with concurrency of 100, and not sending any ETag headers in the requests, with the Node proxy I get 102 requests handled per second, average response time of 975 milliseconds with 90% of responses served within 850 milliseconds; going direct to WCF with the same parameters, I get 53 requests handled per second, mean response time of 1853 milliseconds, with 90% of response served within 3260 milliseconds. Informally monitoring server usage during the tests, Node maxed at 20% CPU and 20Mb memory; IIS maxed at 60% CPU and 100Mb memory.   Note that the sample WCF service does a database read and sleeps for 250 milliseconds to simulate a moderate processing load, so this is *not* a baseline Node-vs-WCF comparison, but for similar scenarios where the  service call is expensive but applicable to numerous clients for a long timespan, the performance boost from the accelerator is considerable.     * - actually, the accelerator will work nicely for any HTTP request, where the URL (path + querystring) uniquely identifies a resource. In the sample, there is an assumption that the ETag is a GUID wrapped in double-quotes (e.g. "28cd4796-76b8-451b-adfd-75cb50a50fa6") – which is the default for WCF services. I use that assumption to name the cache files uniquely, but it is a trivial change to adapt to other ETag formats.

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