Search Results

Search found 31421 results on 1257 pages for 'software performance'.

Page 880/1257 | < Previous Page | 876 877 878 879 880 881 882 883 884 885 886 887  | Next Page >

• Algorithms for modern hardware?

  - by Jurily

  Once again, I find myself with a set of broken assumptions. The article itself is about a 10x performance gain by modifying a proven-optimal algorithm to account for virtual memory: What good is an O(log2(n)) algorithm if those operations cause page faults and slow disk operations? For most relevant datasets an O(n) or even an O(n^2) algorithm, which avoids page faults, will run circles around it. Are there more such algorithms around? Should we re-examine all those fundamental building blocks of our education? What else do I need to watch out for when writing my own?

  Read the article

• How do I use compiler intrinsic __fmul_?

  - by Eric Thoma

  I am writing a massively parallel GPU application. I have been optimizing it by hand. I received a 20% performance increase with _fdividef(x, y), and according to The Cuda C Programming Guide (section C.2.1), using similar functions for multiplication and adding is also beneficial. The function is stated as this: "_fmulrn,rz,ru,rd". __fdividef(x,y) was not stated with the arguments in brackets. I was wondering, what are those brackets? If I run the simple code: int t = __fmul_(5,4); I a compiler error about how _fmul is undefined. I have the CUDA runtime included, so I don't think it is a setup thing; rather it is something to do with those square brackets. How do I correctly use this function? Thank you.

  Read the article

• How to pull a RANDOM and UNIQUE record from SQL via LINQ.

  - by Jeremy H

  Okay, I found lots of posts on SO about how to pull a RANDOM item from the database when using LINQ. There seems to be a couple of differnet ways to handle this. What I need to do though is pull a RANDOM item from the database that the user has not seen before. The data I am pulling from the database is very small. Is there any way I can just hit the database once for 1000 records and then randomly scroll through those? Should I put a cookie on the users system recording the IDs of which items they have seen, pull a random record, check to see if it is seen and if so, pull from the database again? That seems like performance issues just waiting to happen. I don't expect anyone to code it for me, I am just looking for concepts and pointing in the right direction of how I should go about this. Need more details? Just let me know!

  Read the article

• Can any JavaScript library perform as well as the Cut The Rope JavaScript implementation?

  - by joe

  Now that the canvas tag is starting to get hardware execration [acceleration - thanks guys!] by many browsers, developing casual games in HTML5 is becoming more feasible. ZeptoLabs did a great job porting Cut The Rope to HTML5 for use as a Windows 8 Metro App. You can find some of the details here but they do not get into specifics. I was wondering if anyone knew if they used a library (such as Impact or Crafty) or if you need to write all custom and optimized JavaScript code in order to get this type of performance. Thanks!

  Read the article

• How bad is opening and closing a SQL connection for several times? What is the exact effect?

  - by Eren

  For example, I need to fill lots of DataTables with SQLDataAdapter's Fill() method: DataAdapter1.Fill(DataTable1); DataAdapter2.Fill(DataTable2); DataAdapter3.Fill(DataTable3); DataAdapter4.Fill(DataTable4); DataAdapter5.Fill(DataTable5); .... .... Even all the dataadapter objects use the same SQLConnection, each Fill method will open and close the connection unless the connection state is already open before the method call. What I want to know is how does unnecessarily opening and closing SQLConnections affect the performance of the application. How much does it need to scale to see the bad effects of this problem (100,000s of concurrent users?). In a mid-size website (daily 50000 users) does it worth bothering and searching for all the Fill() calls, keeping them together in the code and opening the connection before any Fill() call and closing afterwards?

  Read the article

• Best way to store chat messages and files

  - by Stnaire

  I would like to know what do you think about storing chat messages in a database? I need to be able to bind other stuff to them (like files, or contacts) and using a database is the best way I see for now. The same question comes for files, because they can be bound to chat messages, I have to store them in the database too.. With thousands of messages and files I wonder about performance drops and database size. What do you think considering I'm using PHP with MySQL/Doctrine?

  Read the article

• Is re-using a Command and Connection object in ado.net a legitimate way of reducing new object creat

  - by Neil Trodden

  The current way our application is written, involves creating a new connection and command object in every method that access our sqlite db. Considering we need it to run on a WM5 device, that is leading to hideous performance. Our plan is to use just one connection object per-thread but it's also occurred to us to use one global command object per-thread too. The benefit of this is it reduces the overhead on the garbage collector created by instantiating objects all over the place. I can't find any advice against doing this but wondered if anyone can answer definitively if this is a good or bad thing to do, and why?

  Read the article

• Which data structure for List of objects + datagrid wiev

  - by Martin

  Hi, I have to develop a code which will store a list of objects, as example below 101, value 11, value 12, value 13 ...etc 102, value 21, value 22, value 23 ...etc 103, value 31, value 32, value 33 ...etc 104, value 41, value 42, value 43 ...etc Now, the difficulty is, that first column is an identifier, and whole table should always be sorted by it. Easy access to each element is required. Additionally, list should be easily updated, and extended by adding element at the end as well as in front and still keep being sorted by first column. Finally, I would like to be able to display values of the above in datagridview. What is most important is a performance of the implementation, as rows will be updated many times per second, and datagridview should be able to display all changes immediately. I was thinking about creating class for the values, and then a Dictionary but encountered a problem with displaying values in gridview. What would be the most optimal way of implementing the code? Thanks in advance Martin

  Read the article

• Thread.sleep vs Monitor.Wait vs RegisteredWaitHandle?

  - by Royi Namir

  (the following items has different goals , but im interesting knowing how they "PAUSEd") questions Thread.sleep - Does it impact performance on a system ?does it tie up a thread with its wait ? what about Monitor.Wait ? what is the difference in the way they "wait"? do they tie up a thread with their wait ? what aboutRegisteredWaitHandle ? This method accepts a delegate that is executed when a wait handle is signaled. While it’s waiting, it doesn’t tie up a thread. so some thread are paused and can be woken by a delegate , while others just wait ? spin ? can someone please make things clearer ? edit http://www.albahari.com/threading/part2.aspx

  Read the article

• Using Rails and Rspec, how do you test that the database is not touched by a method

  - by Will Tomlins

  So I'm writing a test for a method which for performance reasons should achieve what it needs to achieve without using SQL queries. I'm thinking all I need to know is what to stub: describe SomeModel do describe 'a_getter_method' do it 'should not touch the database' do thing = SomeModel.create something_inside_rails.should_not_receive(:a_method_querying_the_database) thing.a_getter_method end end end EDIT: to provide a more specific example: class Publication << ActiveRecord::Base end class Book << Publication end class Magazine << Publication end class Student << ActiveRecord::Base has_many :publications def publications_of_type(type) #this is the method I am trying to test. #The test should show that when I do the following, the database is queried. self.publications.find_all_by_type(type) end end describe Student do describe "publications_of_type" do it 'should not touch the database' do Student.create() student = Student.first(:include => :publications) #the publications relationship is already loaded, so no need to touch the DB lambda { student.publications_of_type(:magazine) }.should_not touch_the_database end end end So the test should fail in this example, because the rails 'find_all_by' method relies on SQL.

  Read the article

• How can I synchronize database access between a write-thread and a read-thread?

  - by Runcible

  My program has two threads: Main execution thread that handles user input and queues up database writes A utility thread that wakes up every second and flushes the writes to the database Inside the main thread, I occasionally need to make reads on the database. When this happens, performance is not important, but correctness is. (In a perfect world, I would be reading from a cache, not making a round-trip to the database - but let's put that aside for the sake of discussion.) How do I make sure that the main thread sees a correct / quiescent database? A standard mutex won't work, since I run the risk of having the main thread grab the mutex before the data gets flushed to the database. This would be a big race condition. What I really want is some sort of mutex that lets the main thread of execution proceed only AFTER the mutex has been grabbed and released once. Does such a thing exist? What's the best way to solve this problem?

  Read the article

• Why are gettimeofday() intervals occasionally negative?

  - by Andres Jaan Tack

  I have an experimental library whose performance I'm trying to measure. To do this, I've written the following: struct timeval begin; gettimeofday(&begin, NULL); { // Experiment! } struct timeval end; gettimeofday(&end, NULL); // Print the time it took! std::cout << "Time: " << 100000 * (end.tv_sec - begin.tv_sec) + (end.tv_usec - begin.tv_usec) << std::endl; Occasionally, my results include negative timings, some of which are nonsensical. For instance: Time: 226762 Time: 220222 Time: 210883 Time: -688976 What's going on?

  Read the article

• Filtering with joined tables

  - by viraptor

  I'm trying to get some query performance improved, but the generated query does not look the way I expect it to. The results are retrieved using: query = session.query(SomeModel). options(joinedload_all('foo.bar')). options(joinedload_all('foo.baz')). options(joinedload('quux.other')) What I want to do is filter on the table joined via 'first', but this way doesn't work: query = query.filter(FooModel.address == '1.2.3.4') It results in a clause like this attached to the query: WHERE foos.address = '1.2.3.4' Which doesn't do the filtering in a proper way, since the generated joins attach tables foos_1 and foos_2. If I try that query manually but change the filtering clause to: WHERE foos_1.address = '1.2.3.4' AND foos_2.address = '1.2.3.4' It works fine. The question is of course - how can I achieve this with sqlalchemy itself?

  Read the article

• Is ReaderWriterLockSlim.EnterUpgradeableReadLock() essentially the same as Monitor.Enter()?

  - by Neil Barnwell

  So I have a situation where I may have many, many reads and only the occasional write to a resource shared between multiple threads. A long time ago I read about ReaderWriterLock, and have read about ReaderWriterGate which attempts to mitigate the issue where many writes coming in trump reads and hurt performance. However, now I've become aware of ReaderWriterLockSlim... From the docs, I believe that there can only be one thread in "upgradeable mode" at any one time. In a situation where the only access I'm using is EnterUpgradeableReadLock() (which is appropriate for my scenario) then is there much difference to just sticking with lock(){}? Here's the excerpt: A thread that tries to enter upgradeable mode blocks if there is already a thread in upgradeable mode, if there are threads waiting to enter write mode, or if there is a single thread in write mode. Or, does the recursion policy make any difference to this?

  Read the article

• Self-Configuring Classes W/ Command Line Args: Pattern or Anti-Pattern?

  - by dsimcha

  I've got a program where a lot of classes have really complicated configuration requirements. I've adopted the pattern of decentralizing the configuration and allowing each class to take and parse the command line/configuration file arguments in its c'tor and do whatever it needs with them. (These are very coarse-grained classes that are only instantiated a few times, so there is absolutely no performance issue here.) This avoids having to do shotgun surgery to plumb new options I add through all the levels they need to be passed through. It also avoids having to specify each configuration option in multiple places (where it's parsed and where it's used). What are some advantages/disadvantages of this style of programming? It seems to reduce separation of concerns in that every class is now doing configuration stuff, and to make programs less self-documenting because what parameters a class takes becomes less explicit. OTOH, it seems to increase encapsulation in that it makes each class more self-contained because no other part of the program needs to know exactly what configuration parameters a class might need.

  Read the article

• data between pages: $_SESSION vs. $_GET ?

  - by Haroldo

  Ok, firstly this is not about forms this is about consistent layout as a user explores a site. let me explain: If we imagine a (non-ajax) digital camera online store, say someone was on the DSLR section and specified to view the cameras in Gallery mode and order by price. They then click onto the Compact camera's page. It would be in the users interests if the 'views' they selected we're carried over to this new page. Now, i'd say use a session - am i wrong? are there performance issues i should be aware of for a few small session vars ( ie view=1 , orderby=price) ?

  Read the article

• Validating Column Data Stored as CSV Against Another Table

  - by Jakkwylde

  I wanted to see what some suggested approaches would be to validate a field that is stored as a CSV against a table containing appropriate values. Althought it would be desired, it is NOT an option to split the CSV list into another related table. In the example data below I would be trying to capture the code 99 for widget A. Below is an example data representation. Table: Widgets WidgetName WidgetCodeList A 1, 2, 3 B 1 C 2, 3 D 99 Table: WidgetCodes WidgetCode 1 2 3 An earlier approach was to query the CSV column as rows using various string manipulations and CONNECT_BY_LEVEL however the performance was not acceptible.

  Read the article

• BDD-testing using a UI driver (e.g. Selenium for a web-application)

  - by jonathanconway

  Can BDD (Behavior Driven Design) tests be implemented using a UI driver? For example, given a web application, instead of: Writing tests for the back-end, and then more tests in Javascript for the front-end Should I: Write the tests as Selenium macros, which simulate mouse-clicks, etc in the actual browser? The advantages I see in doing it this way are: The tests are written in one language, rather than several They're focussed on the UI, which gets developers thinking outside-in They run in the real execution environment (the browser), which allows us to Test different browsers Test different servers Get insight into real-world performance Thoughts?

  Read the article

• Best way to daemonize Java application on Linux

  - by SyBer

  Hi. While I found this question being answered here on SW several times, I didn't find a concluding answer what is the best approach. I'm not looking to use any external wrapper, as I found them launching the java process under a nice level lower then themselves which potentially lowers the performance, so it seems only the shell methods are left. I so far found 3 different shell methods: start-stop-daemon RedHat daemon init.d function nohup on start / disown after start What you people are using, and can recommend as the most reliable method? Thanks.

  Read the article

• Element point map for html5 canvas element, need algorithm

  - by Artiom Chilaru

  I'm currently working on a pure html 5 canvas implementation of the "flying tag cloud sphere", which many of you have undoubtedly seen as a flash object in some pages. The tags are drawn fine, and the performance is satisfactory, but there's one thing in the canvas element that's kind of breaking this idea: you can't identify the objects that you've drawn on a canvas, as it's just a simple flat "image".. What I have to do in this case is catch the click event, and try to "guess" which element was clicked. So I have to have some kind of matrix, which stores a link to a tag object for each pixel on the canvas, AND I have to update this matrix on every redraw. Now this sounds incredibly inefficient, and before I even start trying to implement this, I want to ask the community - is there some "well known" algorithm that would help me in this case? Or maybe I'm just missing something, and the answer is right behind the corner? :)

  Read the article

• What is the differnce between "LINQ to Entities", "LINQ to SQL" and "LINQ to Dataset".

  - by Marcel

  Hi all, I'm working for quite a while now with LINQ. However, it remained still a bit of a mystery what are the real differences between the mentioned flavours of LINQ. The successful answer will contain a short differentiation between them. What is the main goal if it, what is the benefit, and is there a performance impact... P.S. I know that there are a lot of information sources out there, but I look for a kind of a "cheat sheet" which instructs a newbie where to head to for a specific goal.

  Read the article

• Why don't scripting languages output Unicode to the Windows console?

  - by hippietrail

  The Windows console has been Unicode aware for at least a decade and perhaps as far back as Windows NT. However for some reason the major cross-platform scripting languages including Perl and Python only ever output various 8-bit encodings, requiring much trouble to work around. Perl gives a "wide character in print" warning, Pythong gives a charmap error and quits. Why on earth after all these years do they not just simply call the Win32 -W APIs that output UTF-16 Unicode instead of forcing everything through the ANSI/codepage bottleneck? Is it just that cross-platform performance is low priority? Is it that the languages use UTF-8 internally and find it too much bother to output UTF-16? Or are the -W APIs inherently broken to such a degree that they can't be used as-is?

  Read the article

• How to update only certain items in a list when using MVC?

  - by Eugen

  I'm building a GUI that includes a list with quite a lot of items. I allow the user to add/delete/edit those items. Up until now my update method called in the controller implied an entire JList reset (with its obvious performance issues). Now that there are hundreds of items available, updating the entire list is not fezable any longer. Does anyone know of a tutorial or can share an example (I haven't found any to suit my needs so far) in which the JList is updated something like JList.update(startIndex, endIndex);? Thanks for taking the time to answer.

  Read the article

• How to implement Voting for Grails Domain Classes?

  - by userWebMobile

  I have a Book class and need to implement a yes/no voting functionality. My domain classes look like this: class Book { String title static hasMany = [votes: Vote] } class User { String name static hasMany = [votes: Vote] } class Vote { boolean yesVote static belongsTo = [user: User, book: Book] } What is the best way to implement a voting for the book class. I need the following informations: What is the average yesVote for a book over all votes (either yes or no)? How to check if a specific user has done a vote? What is the best way to implement the computation of the average yesVote such that the performance does not drop?

  Read the article

• Scripting language to embed into a Java server application

  - by Alexey Kalmykov

  I want to make a business logic of server side Java application as a set of scripts. So I need from a scripting engine: Maximum Java interoperability (i.e. Spring framework) Script reloading and recompiling Easy DB access from scripting language Clear and simple syntax (some DSL capabilities would be nice to have), easy learning curve for non-hardcore developers Performance and stability I had some experience in the similar project with Rhino and it was pretty good. But I want to see if there is something better. Currently I'm looking into Groovy. JRuby and Jython are a bit more complex than I need for this task. Any other suggestion? What to take into consideration?

  Read the article

< Previous Page | 876 877 878 879 880 881 882 883 884 885 886 887  | Next Page >