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  • Does async and await incease performance of an ASP.Net application

    - by Kerezo
    I recently read a article about c#-5 and new $ nice asynchronous programming. I see it works greate in windows application. The question came to me before is if this feature can increase ASP.Net performance? consider this code: public T GetData() { var d = GetSomeData(); return d; } and public async T GetData2() { var d = await GetSomeData(); return d; } Has in an ASP.Net appication that two codes difference? thanks

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  • C++ STL: Array vs Vector: Raw element accessing performance

    - by oh boy
    I'm building an interpreter and as I'm aiming for raw speed this time, every clock cycle matters for me in this (raw) case. Do you have any experience or information what of the both is faster: Vector or Array? All what matters is the speed I can access an element (opcode receiving), I don't care about inserting, allocation, sorting, etc. I'm going to lean myself out of the window now and say: Arrays are at least a bit faster than vectors in terms of accessing an element i. It seems really logical for me. With vectors you have all those security and controlling overhead which doesn't exist for arrays. (Why) Am I wrong? No, I can't ignore the performance difference - even if it is so small - I have already optimized and minimized every other part of the VM which executes the opcodes :)

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  • Performance effect of using print statements in Python script

    - by Sudar
    I have a Python script that process a huge text file (with around 4 millon lines) and writes the data into two separate files. I have added a print statement, which outputs a string for every line for debugging. I want to know how bad it could be from the performance perspective? If it is going to very bad, I can remove the debugging line. Edit It turns out that having a print statement for every line in a file with 4 million lines is increasing the time way too much.

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  • Performance: Subquery or Joining

    - by Auro
    Hello I got a little question about performance of a subquery / joining another table INSERT INTO Original.Person ( PID, Name, Surname, SID ) ( SELECT ma.PID_new , TBL.Name , ma.Surname, TBL.SID FROM Copy.Person TBL , original.MATabelle MA WHERE TBL.PID = p_PID_old AND TBL.PID = MA.PID_old ); This is my SQL, now this thing runs around 1 million times or more. Now my question is what would be faster? if I change TBL.SID to (Select new from helptable where old = tbl.sid) or if I add helptable to the from and do the joining in the where? greets Auro

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  • Does 'throw' or 'try...catch' hinder performance?

    - by Richard
    I've been reading all over the place (including here) about when exception should / shouldn't be used. I now want to change my code that would throw to make the method return false and handle it like that, but my question is: Is it the throwing or try..catch-ing that can hinder performance...? What I mean is, would this be acceptable: bool method someMmethod() { try { // ...Do something catch (Exception ex) // Don't care too much what at the moment... { // Output error // Return false } return true // No errors Or would there be a better way to do it? (I'm bloody sick of seeing "Unhandled exception..." LOL!)

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  • Performance problem on a query.

    - by yapiskan
    Hi, I have a performance problem on a query. First table is a Customer table which has millions records in it. Customer table has a column of email address and some other information about customer. Second table is a CommunicationInfo table which contains just Email addresses. And What I want in here is; how many times the email address in CommunicationInfo table repeats in Customers table. What could be the the most performer query. The basic query that I can explain this situation is; Select ci.Email, count(*) from Customer c left join CommunicationInfo ci on c.Email1 = ci.Email or c.Email2 = ci.Email Group by ci.Email But sure, it takes about 5, 6 minutes in execution. Thanks in Advance.

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  • Slow performance of query

    - by user642378
    Hi, I have asked the performance of query and i tried to simplyfy it.but still it not works.I am adding my query below.Please can you simplify it more effectively select r.parent_itemid f_id, parent_item.name f_name, parent_item.typeid f_typeid, parent_item.ownerid f_ownerid, parent_item.created f_created, parent_item.modifiedby f_modifiedby, parent_item.modified f_modified, pt.name f_tname, child_item.id i_id, t.name i_tname, child_item.typeid i_typeid, child_item.name i_name, child_item.ownerid i_ownerid, child_item.created i_created, child_item.modifiedby i_modifiedby, child_item.modified i_modified, r.ordinal i_ordinal from item child_item, type t, relation r, item parent_item, type pt where r.child_itemid = child_item.id and t.id=child_item.typeid and parent_item.id = r.parent_itemid and pt.id = parent_item.typeid and parent_item.id in ( select itemid from permission where itemid=parent_item.id and (holder_itemid in (10,100) and level > 0) ) order by r.parent_itemid, r.relation_typeid, r.ordinal Thanks you regards jennie

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  • Investigation: Can different combinations of components effect Dataflow performance?

    - by jamiet
    Introduction The Dataflow task is one of the core components (if not the core component) of SQL Server Integration Services (SSIS) and often the most misunderstood. This is not surprising, its an incredibly complicated beast and we’re abstracted away from that complexity via some boxes that go yellow red or green and that have some lines drawn between them. Example dataflow In this blog post I intend to look under that facade and get into some of the nuts and bolts of the Dataflow Task by investigating how the decisions we make when building our packages can affect performance. I will do this by comparing the performance of three dataflows that all have the same input, all produce the same output, but which all operate slightly differently by way of having different transformation components. I also want to use this blog post to challenge a common held opinion that I see perpetuated over and over again on the SSIS forum. That is, that people assume adding components to a dataflow will be detrimental to overall performance. Its not surprising that people think this –it is intuitive to think that more components means more work- however this is not a view that I share. I have always been of the opinion that there are many factors affecting dataflow duration and the number of components is actually one of the less important ones; having said that I have never proven that assertion and that is one reason for this investigation. I have actually seen evidence that some people think dataflow duration is simply a function of number of rows and number of components. I’ll happily call that one out as a myth even without any investigation!  The Setup I have a 2GB datafile which is a list of 4731904 (~4.7million) customer records with various attributes against them and it contains 2 columns that I am going to use for categorisation: [YearlyIncome] [BirthDate] The data file is a SSIS raw format file which I chose to use because it is the quickest way of getting data into a dataflow and given that I am testing the transformations, not the source or destination adapters, I want to minimise external influences as much as possible. In the test I will split the customers according to month of birth (12 of those) and whether or not their yearly income is above or below 50000 (2 of those); in other words I will be splitting them into 24 discrete categories and in order to do it I shall be using different combinations of SSIS’ Conditional Split and Derived Column transformation components. The 24 datapaths that occur will each input to a rowcount component, again because this is the least resource intensive means of terminating a datapath. The test is being carried out on a Dell XPS Studio laptop with a quad core (8 logical Procs) Intel Core i7 at 1.73GHz and Samsung SSD hard drive. Its running SQL Server 2008 R2 on Windows 7. The Variables Here are the three combinations of components that I am going to test:     One Conditional Split - A single Conditional Split component CSPL Split by Month of Birth and income category that will use expressions on [YearlyIncome] & [BirthDate] to send each row to one of 24 outputs. This next screenshot displays the expression logic in use: Derived Column & Conditional Split - A Derived Column component DER Income Category that adds a new column [IncomeCategory] which will contain one of two possible text values {“LessThan50000”,”GreaterThan50000”} and uses [YearlyIncome] to determine which value each row should get. A Conditional Split component CSPL Split by Month of Birth and Income Category then uses that new column in conjunction with [BirthDate] to determine which of the same 24 outputs to send each row to. Put more simply, I am separating the Conditional Split of #1 into a Derived Column and a Conditional Split. The next screenshots display the expression logic in use: DER Income Category         CSPL Split by Month of Birth and Income Category       Three Conditional Splits - A Conditional Split component that produces two outputs based on [YearlyIncome], one for each Income Category. Each of those outputs will go to a further Conditional Split that splits the input into 12 outputs, one for each month of birth (identical logic in each). In this case then I am separating the single Conditional Split of #1 into three Conditional Split components. The next screenshots display the expression logic in use: CSPL Split by Income Category         CSPL Split by Month of Birth 1& 2       Each of these combinations will provide an input to one of the 24 rowcount components, just the same as before. For illustration here is a screenshot of the dataflow containing three Conditional Split components: As you can these dataflows have a fair bit of work to do and remember that they’re doing that work for 4.7million rows. I will execute each dataflow 10 times and use the average for comparison. I foresee three possible outcomes: The dataflow containing just one Conditional Split (i.e. #1) will be quicker There is no significant difference between any of them One of the two dataflows containing multiple transformation components will be quicker Regardless of which of those outcomes come to pass we will have learnt something and that makes this an interesting test to carry out. Note that I will be executing the dataflows using dtexec.exe rather than hitting F5 within BIDS. The Results and Analysis The table below shows all of the executions, 10 for each dataflow. It also shows the average for each along with a standard deviation. All durations are in seconds. I’m pasting a screenshot because I frankly can’t be bothered with the faffing about needed to make a presentable HTML table. It is plain to see from the average that the dataflow containing three conditional splits is significantly faster, the other two taking 43% and 52% longer respectively. This seems strange though, right? Why does the dataflow containing the most components outperform the other two by such a big margin? The answer is actually quite logical when you put some thought into it and I’ll explain that below. Before progressing, a side note. The standard deviation for the “Three Conditional Splits” dataflow is orders of magnitude smaller – indicating that performance for this dataflow can be predicted with much greater confidence too. The Explanation I refer you to the screenshot above that shows how CSPL Split by Month of Birth and salary category in the first dataflow is setup. Observe that there is a case for each combination of Month Of Date and Income Category – 24 in total. These expressions get evaluated in the order that they appear and hence if we assume that Month of Date and Income Category are uniformly distributed in the dataset we can deduce that the expected number of expression evaluations for each row is 12.5 i.e. 1 (the minimum) + 24 (the maximum) divided by 2 = 12.5. Now take a look at the screenshots for the second dataflow. We are doing one expression evaluation in DER Income Category and we have the same 24 cases in CSPL Split by Month of Birth and Income Category as we had before, only the expression differs slightly. In this case then we have 1 + 12.5 = 13.5 expected evaluations for each row – that would account for the slightly longer average execution time for this dataflow. Now onto the third dataflow, the quick one. CSPL Split by Income Category does a maximum of 2 expression evaluations thus the expected number of evaluations per row is 1.5. CSPL Split by Month of Birth 1 & CSPL Split by Month of Birth 2 both have less work to do than the previous Conditional Split components because they only have 12 cases to test for thus the expected number of expression evaluations is 6.5 There are two of them so total expected number of expression evaluations for this dataflow is 6.5 + 6.5 + 1.5 = 14.5. 14.5 is still more than 12.5 & 13.5 though so why is the third dataflow so much quicker? Simple, the conditional expressions in the first two dataflows have two boolean predicates to evaluate – one for Income Category and one for Month of Birth; the expressions in the Conditional Split in the third dataflow however only have one predicate thus they are doing a lot less work. To sum up, the difference in execution times can be attributed to the difference between: MONTH(BirthDate) == 1 && YearlyIncome <= 50000 and MONTH(BirthDate) == 1 In the first two dataflows YearlyIncome <= 50000 gets evaluated an average of 12.5 times for every row whereas in the third dataflow it is evaluated once and once only. Multiply those 11.5 extra operations by 4.7million rows and you get a significant amount of extra CPU cycles – that’s where our duration difference comes from. The Wrap-up The obvious point here is that adding new components to a dataflow isn’t necessarily going to make it go any slower, moreover you may be able to achieve significant improvements by splitting logic over multiple components rather than one. Performance tuning is all about reducing the amount of work that needs to be done and that doesn’t necessarily mean use less components, indeed sometimes you may be able to reduce workload in ways that aren’t immediately obvious as I think I have proven here. Of course there are many variables in play here and your mileage will most definitely vary. I encourage you to download the package and see if you get similar results – let me know in the comments. The package contains all three dataflows plus a fourth dataflow that will create the 2GB raw file for you (you will also need the [AdventureWorksDW2008] sample database from which to source the data); simply disable all dataflows except the one you want to test before executing the package and remember, execute using dtexec, not within BIDS. If you want to explore dataflow performance tuning in more detail then here are some links you might want to check out: Inequality joins, Asynchronous transformations and Lookups Destination Adapter Comparison Don’t turn the dataflow into a cursor SSIS Dataflow – Designing for performance (webinar) Any comments? Let me know! @Jamiet

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  • Why am I getting "ArgumentError: wrong number of arguments (1 for 0)" when running my rails function

    - by Hisham
    I'm stumped on what's causing this. I get this error and stack trace in all my functional tests where I call 'post'. Here is the full stack trace: 7) Error: test_should_validate(UsersControllerTest): ArgumentError: wrong number of arguments (1 for 0) /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route.rb:48:in `to_query' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route.rb:48:in `build_query_string' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route.rb:46:in `each' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route.rb:46:in `build_query_string' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route.rb:233:in `append_query_string' generated code (/Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route.rb:154):3:in `generate' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route_set.rb:365:in `__send__' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route_set.rb:365:in `generate' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route_set.rb:364:in `each' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route_set.rb:364:in `generate' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/url_rewriter.rb:208:in `rewrite_path' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/url_rewriter.rb:187:in `rewrite_url' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/url_rewriter.rb:165:in `rewrite' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/test_process.rb:450:in `build_request_uri' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/test_process.rb:406:in `process' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/test_process.rb:376:in `post' functional/users_controller_test.rb:57:in `test_should_validate' /Users/hisham/src/rails/ftuBackend/vendor/rails/activesupport/lib/active_support/testing/setup_and_teardown.rb:60:in `__send__' /Users/hisham/src/rails/ftuBackend/vendor/rails/activesupport/lib/active_support/testing/setup_and_teardown.rb:60:in `run' This is the test I'm running: def test_should_validate post :validate, :user => { :email => '[email protected]', :password => 'quire', :password_confirmation => 'quire', :agreed_to_terms => "true" } assert assigns(:user).errors.empty? assert_response :success end

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  • DataView.RowFilter Vs DataTable.Select() vs DataTable.Rows.Find()

    - by Aseem Gautam
    Considering the code below: Dataview someView = new DataView(sometable) someView.RowFilter = someFilter; if(someView.count > 0) { …. } Quite a number of articles which say Datatable.Select() is better than using DataViews, but these are prior to VS2008. Solved: The Mystery of DataView's Poor Performance with Large Recordsets Array of DataRecord vs. DataView: A Dramatic Difference in Performance Googling on this topic I found some articles/forum topics which mention Datatable.Select() itself is quite buggy(not sure on this) and underperforms in various scenarios. On this(Best Practices ADO.NET) topic on msdn it is suggested that if there is primary key defined on a datatable the findrows() or find() methods should be used insted of Datatable.Select(). This article here (.NET 1.1) benchmarks all the three approaches plus a couple more. But this is for version 1.1 so not sure if these are valid still now. Accroding to this DataRowCollection.Find() outperforms all approaches and Datatable.Select() outperforms DataView.RowFilter. So I am quite confused on what might be the best approach on finding rows in a datatable. Or there is no single good way to do this, multiple solutions exist depending upon the scenario?

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  • How do I use PerformanceCounterType AverageTimer32?

    - by Patrick J Collins
    I'm trying to measure the time it takes to execute a piece of code on my production server. I'd like to monitor this information in real time, so I decided to give Performance Analyser a whizz. I understand from MSDN that I need to create both an AverageTimer32 and an AverageBase performance counter, which I duly have. I increment the counter in my program, and I can see the CallCount go up and down, but the AverageTime is always zero. What am I doing wrong? Thanks! Here's a snippit of code : long init_call_time = Environment.TickCount; // *** // Lots and lots of code... // *** // Count number of calls PerformanceCounter perf = new PerformanceCounter("Cat", "CallCount", "Instance", false); perf.Increment(); perf.Close(); // Count execution time PerformanceCounter perf2 = new PerformanceCounter("Cat", "CallTime", "Instance", false); perf2.NextValue(); perf2.IncrementBy(Environment.TickCount - init_call_time); perf2.Close(); // Average base for execution time PerformanceCounter perf3 = new PerformanceCounter("Cat", "CallTimeBase", "Instance", false); perf3.Increment(); perf3.Close(); perf2.NextValue();

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  • Ruby on rails generates tests for you. Do those give a false sense of a safety net?

    - by Hamish Grubijan
    Disclaimer: I have not used RoR, and I have not generated tests. But, I will still dare to post this question. Quality Assurance is theoretically impossible to get 100% right in general (Undecidable problem ;), and it is hard in practice. So many developers do not understand that writing good automated tests is an art, and it is hard. When I hear that RoR generates the tests for you, I get very skeptical. It cannot be that easy. Testing is a general concept; it applies across languages. So does the concept of code contracts, it is similar for languages that support it. Code contracts do not generate themselves. The programmer must add the requirements and the promises manually, after doing some thinking about the algorithm / function. If a human gets it wrong, then the tools will propagate the error. Similarly with testing - it takes human judgement about what should happen. Tests do not write themselves, and we are far from the day when a business analyst can just have a conversation with a computer and tell it informally what the requirements are and have the computer do all the work. There is no magic ... how can RoR generate good tests for you? Please shed some light on this. Opinions are ok, for this is a community wiki. Thanks!

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  • How do I run JUnit from NetBeans?

    - by FarmBoy
    I've been trying to understand how to start writing and running JUnit tests. When I'm reading this article: http://junit.sourceforge.net/doc/testinfected/testing.htm I get the the middle of the page and they write, "JUnit comes with a graphical interface to run tests. Type the name of your test class in the field at the top of the window. Press the Run button." I don't know how to launch this program. I don't even know which package it is in, or how you run a library class from an IDE. Being stuck, I tried this NetBeans tutorial: http://www.netbeans.org/kb/docs/java/junit-intro.html It seemed to be going OK, but then I noticed that the menu options for this tutorial for testing a Java Class Library are different from those for a regular Java application, or for a Java Web App. So the instructions in this tutorial don't apply generally. I'm using NetBeans 6.7, and I've imported JUnit 4.5 into the libraries folder. What would be the normal way to run JUnit, after having written the tests? The JUnit FAQ describes the process from the Console, and I'm willing to do that if that is what is typical, but given all that I can do inside netbeans, it seems hard to believe that there isn't an easier way. Thanks much. EDIT: If I right-click on the project and select "Test" the output is: init: deps-jar: compile: compile-test: test-report: test: BUILD SUCCESSFUL (total time: 0 seconds) This doesn't strike me as the desired output of a test, especially since this doesn't change whether the test condition is true or not. Any ideas?

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  • How to get decent MySQL driver perfomance in Ruby

    - by Zombies
    I notice that I am getting very poor performance for either or both inserts and queries. The queries themselves are basic and can execute with no delay directly from mysql. The ruby script that I wrote is only 1 thread, so only 1 connection is being used, and never closed unless the script is terminated. Pretty basic, I am just trying to insert a lot of rows. There is a look-up or two to get a surrogate key, or to check for duplicates, but the complexity is just O(n). Also, it isn't like there are millions of records, so again the queries themselves take no time to run. I am using: Ruby 1.9.1 Gem/driver:ruby-mysql 2.9.2 MySQL 5.1.37-1ubuntu5.1 ^ all 32 bit versions on a 32bit ubuntu distro I am getting about 1-2 inserts per second, pretty slow. I know a lot of people will suggest to change drivers, but that means I have some refactoring and resting to do. So I would really appreciate any help, but please if you do recomend that at least say why you do (eg: if you have used ruby-mysql x.x.x before and found another mysql driver to be better).ruby-mysql 2.9.2 What I would like to know: How can I improve performance with ruby-mysql 2.9.2 If and only if I cannot do this with ruby-mysql 2.9.2, what should I do?

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  • Will IOC solve our problems?

    - by user127954
    Just trying to implement unit testing into a brownfield type system. Be aware i'm relatively new into the unit testing world. Its going to be a gradual migration of course because there are just so many areas of pain. The current problem i'm trying to solve is we followed a lot of bad practices from our VB6 days and in the conversion of our app to .Net. We have LOT AN LOTS of shared/static functions which call other shared functions and those call others and so on. Sometimes depedencies are passed in as parameters and sometimes they are just newed up within the calling function. I've already instructed our developers to stop creating shared functions and instead create instance members and only use those instance members off of interfaces but that doesn't alleviate the current situation. So you must recursively pass in each and every dependency at the top layer for each function in your code path and method signatures are turning into a mess. I'm hoping this is something that IOC will fix. Currently we are using NUnit/Moq and i'm starting to investigate StructureMap. So far i understand that you pretty much tell StructureMap for x interface i want to default to the concrete class y: ObjectFactory.Initialize(x=>{x.ForRequestType<IInterface>().TheDefaultIsConcreteType<MyClass>()}); Then to runtime: var mytype = ObjectFactory.GetInstance<IInterface>(); the IOC container will initialize the correct type for you. Not sure yet how to swap a fake in for the concrete type but hopefully thats simple. Again will IOC solve the problems i was talking about above? Is there a specific IOC framework that will do it better than StructureMap or can they all handle this situation. Any help would be much appreciated.

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  • externalizing junit stub objects.

    - by Ajay
    Hi!    In my project we created stub files for testing junits in java(factories) itself. However, we have to externalize these stubs. After seeing a number of serializers/deserializers, we settled on using XStream to serialize and deserialize these stub objects. XStream works like a charm. Its pretty good at what it claims to be. Previously, we had a single factory class say AFactory which produced all the stubs needed for testing different test cases. Now when externalizing each of the stub generated, we hit a road block. We had to create 1 xml file for each stub produced by the factory. For example, public final class AFactory{ public static A createStub1(){ /*Code here */} public static A createStub2(){ /*Code here */} public static A createStub3(){ /*Code here */} } Now, when trying to move this stubs to external files, we had to create 1 xml file for each stub created(A-stub1.xml, A-stub2.xml and A-stub3.xml). The problem with this approach is that, it leads to proliferation of xml stub files. I was thinking, how about keeping all the stubs related to a single bean class in a single xml file. <?xml version="1.0"?> <stubs class="A"> <stub id="stub1"> <!-- Here comes the externalized xml stub representation --> </stub> <stub id="stub2"> </stub> </stubs> Is there a framework which allows you keep all the stub in xml representation in a single xml file as above ? Or What do you guys suggest should be the right approach to adhere to ?

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  • Using Oracle hint "FIRST_ROWS" to improve Oracle database performances

    - by bobetko
    I have a statement that runs on Oracle database server. The statement has about 5 joins and there is nothing unusual there. It looks pretty much like below: SELECT field1, field2, field3, ... FROM table1, table2, table3, table4, table5 WHERE table1.id = table2.id AND table2.id = table3.id AND ... table5.userid = 1 The problem (and what is interesting) is that statement for userid = 1 takes 1 second to return 590 records. Statement for userid = 2 takes around 30 seconds to return 70 records. I don't understand why is difference so big. It seems that different execution plan is chosen for statement with userid = 1 and different for userid = 2. After I implemented Oracle Hint FIRST_ROW, performance become significantly better. Both statements (for both ids 1 and 2) produce return in under 1 second. SELECT /*+ FIRST_ROWS */ field1, field2, field3, ... FROM table1, table2, table3, table4, table5 WHERE table1.id = table2.id AND table2.id = table3.id AND ... table5.userid = 1 Questions: 1) What are possible reasons for bad performance when userid = 2 (when hint is not used)? 2) Why would execution plan be different for one vs another statement (when hint is not used)? 3) Is there anything that I should be careful about when deciding to add this hint to my queries? Thanks

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  • Will fixed-point arithmetic be worth my trouble?

    - by Thomas
    I'm working on a fluid dynamics Navier-Stokes solver that should run in real time. Hence, performance is important. Right now, I'm looking at a number of tight loops that each account for a significant fraction of the execution time: there is no single bottleneck. Most of these loops do some floating-point arithmetic, but there's a lot of branching in between. The floating-point operations are mostly limited to additions, subtractions, multiplications, divisions and comparisons. All this is done using 32-bit floats. My target platform is x86 with at least SSE1 instructions. (I've verified in the assembler output that the compiler indeed generates SSE instructions.) Most of the floating-point values that I'm working with have a reasonably small upper bound, and precision for near-zero values isn't very important. So the thought occurred to me: maybe switching to fixed-point arithmetic could speed things up? I know the only way to be really sure is to measure it, that might take days, so I'd like to know the odds of success beforehand. Fixed-point was all the rage back in the days of Doom, but I'm not sure where it stands anno 2010. Considering how much silicon is nowadays pumped into floating-point performance, is there a chance that fixed-point arithmetic will still give me a significant speed boost? Does anyone have any real-world experience that may apply to my situation?

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  • java.lang.IllegalStateException: missing behavior definition for the preceding method call getMessag

    - by user362199
    Hi All, I'm using EasyMock(version 2.4) and TestNG for writing UnitTest. I have a following scenario and I cannot change the way class hierarchy is defined. I'm testing ClassB which is extending ClassA. ClassB look like this public class ClassB extends ClassA { public ClassB() { super("title"); } @Override public String getDisplayName() { return ClientMessages.getMessages("ClassB.title"); } } ClassA code public abstract class ClassA { private String title; public ClassA(String title) { this.title = ClientMessages.getMessages(title); } public String getDisplayName() { return this.title; } } ClientMessages class code public class ClientMessages { private static MessageResourse messageResourse; public ClientMessages(MessageResourse messageResourse) { this.messageResourse = messageResourse; } public static String getMessages(String code) { return messageResourse.getMessage(code); } } MessageResourse Class code public class MessageResourse { public String getMessage(String code) { return code; } } Testing ClassB import static org.easymock.classextension.EasyMock.createMock; import org.easymock.classextension.EasyMock; import org.testng.Assert; import org.testng.annotations.Test; public class ClassBTest { private MessageResourse mockMessageResourse = createMock(MessageResourse.class); private ClassB classToTest; private ClientMessages clientMessages; @Test public void testGetDisplayName() { EasyMock.expect(mockMessageResourse.getMessage("ClassB.title")).andReturn("someTitle"); clientMessages = new ClientMessages(mockMessageResourse); classToTest = new ClassB(); Assert.assertEquals("someTitle" , classToTest.getDisplayName()); EasyMock.replay(mockMessageResourse); } } When I'm running this this test I'm getting following exception: java.lang.IllegalStateException: missing behavior definition for the preceding method call getMessage("title") While debugging what I found is, it's not considering the mock method call mockMessageResourse.getMessage("ClassB.title") as it has been called from the construtor (ClassB object creation). Can any one please help me how to test in this case. Thanks.

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  • Optimizing code using PIL

    - by freakazo
    Firstly sorry for the long piece of code pasted below. This is my first time actually having to worry about performance of an application so I haven't really ever worried about performance. This piece of code pretty much searches for an image inside another image, it takes 30 seconds to run on my computer, converting the images to greyscale and other changes shaved of 15 seconds, I need another 15 shaved off. I did read a bunch of pages and looked at examples but I couldn't find the same problems in my code. So any help would be greatly appreciated. From the looks of it (cProfile) 25 seconds is spent within the Image module, and only 5 seconds in my code. from PIL import Image import os, ImageGrab, pdb, time, win32api, win32con import cProfile def GetImage(name): name = name + '.bmp' try: print(os.path.join(os.getcwd(),"Images",name)) image = Image.open(os.path.join(os.getcwd(),"Images",name)) except: print('error opening image;', name) return image def Find(name): image = GetImage(name) imagebbox = image.getbbox() screen = ImageGrab.grab() #screen = Image.open(os.path.join(os.getcwd(),"Images","Untitled.bmp")) YLimit = screen.getbbox()[3] - imagebbox[3] XLimit = screen.getbbox()[2] - imagebbox[2] image = image.convert("L") Screen = screen.convert("L") Screen.load() image.load() #print(XLimit, YLimit) Found = False image = image.getdata() for y in range(0,YLimit): for x in range(0,XLimit): BoxCoordinates = x, y, x+imagebbox[2], y+imagebbox[3] ScreenGrab = screen.crop(BoxCoordinates) ScreenGrab = ScreenGrab.getdata() if image == ScreenGrab: Found = True #print("woop") return x,y if Found == False: return "Not Found" cProfile.run('print(Find("Login"))')

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  • asp.net mvc - How to create fake test objects quickly and efficiently

    - by Simon G
    Hi, I'm currently testing the controller in my mvc app and I'm creating a fake repository for testing. However I seem to be writing more code and spending more time for the fakes than I do on the actual repositories. Is this right? The code I have is as follows: Controller public partial class SomeController : Controller { IRepository repository; public SomeController(IRepository rep) { repository = rep; } public virtaul ActionResult Index() { // Some logic var model = repository.GetSomething(); return View(model); } } IRepository public interface IRepository { Something GetSomething(); } Fake Repository public class FakeRepository : IRepository { private List<Something> somethingList; public FakeRepository(List<Something> somethings) { somthingList = somthings; } public Something GetSomething() { return somethingList; } } Fake Data class FakeSomethingData { public static List<Something> CreateSomethingData() { var somethings = new List<Something>(); for (int i = 0; i < 100; i++) { somethings.Add(new Something { value1 = String.Format("value{0}", i), value2 = String.Format("value{0}", i), value3 = String.Format("value{0}", i) }); } return somethings; } } Actual Test [TestClass] public class SomethingControllerTest { SomethingController CreateSomethingController() { var testData = FakeSomethingData.CreateSomethingData(); var repository = new FakeSomethingRepository(testData); SomethingController controller = new SomethingController(repository); return controller; } [TestMethod] public void SomeTest() { // Arrange var controller = CreateSomethingController(); // Act // Some test here // Arrange } } All this seems to be a lot of extra code, especially as I have more than one repository. Is there a more efficient way of doing this? Maybe using mocks? Thanks

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  • Java repaint is slow under certain conditions.

    - by Gabriel A. Zorrilla
    I'm doing a simple grid which each square is highlighted by the cursor: They are a couple of JPanels, mapgrid and overlay inside a JLayeredPane, with mapgrid on the bottom. Mapgrid just draws on initialization the grid, its paint metodh is: public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g; g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); for (int i = 0; i < h; i++) { for (int j = 0; j < w; j++) { g2d.setColor(new Color(128, 128, 128, 255)); g2d.drawRect(tileSize * j, i * tileSize, tileSize, tileSize); } } In the overlay JPanel is where the highlighting occurs, this is what is repainted when the mouse is moved: public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g; g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2d.setColor(new Color(255, 255, 128, 255)); g2d.drawRect((pointerX/tileSize)*tileSize,(pointerY/ tileSize)*tileSize, tileSize, tileSize); } I noticed that even though the base layer (mapgrid) is NOT repainted when the mouse moves, just the transparent overlay layer, the performance is lacking. If i give the overlay JPanel a background, its way faster. If i remove the mapgrid Antialiasing, its a bit faster too. I don't know why giving a background to the overlay layer (and thus, hiding the mapgrid) or disabling antialiasing in the mapgrid leads to much better performance. Is there a better way to do this? Why does this happen?

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  • Basic jUnit Questions

    - by Epitaph
    I was testing a String multiplier class with a multiply() method that takes 2 numbers as inputs (as String) and returns the result number (as String) `public String multiply(String num1, String num2); I have done the implementation and created a test class with the following test cases involving the input String parameter as 1) valid numbers 2) characters 3) special symbol 4) empty string 5) Null value 6) 0 7) Negative number 8) float 9) Boundary values 10) Numbers that are valid but their product is out of range 11) numbers will + sign (+23) 1) I'd like to know if "each and every" assertEquals() should be in it's own test method? Or, can I group similar test cases like testInvalidArguments() to contains all asserts involving invalid characters since ALL of them throw the same NumberFormatException ? 2) If testing an input value like character ("a"), do I need to include test cases for ALL scenarios? "a" as the first argument "a" as the second argument "a" and "b" as the 2 arguments 3) As per my understanding, the benefit of these unit tests is to find out the cases where the input from a user might fail and result in an exception. And, then we can give the user with a meaningful message (asking them to provide valid input) instead of an exception. Is that the correct? And, is it the only benefit? 4) Are the 11 test cases mentioned above sufficient? Did I miss something? Did I overdo? When is enough? 5) Following from the above point, have I successfully tested the multiply() method?

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  • Defining jUnit Test cases Correctly

    - by Epitaph
    I am new to Unit Testing and therefore wanted to do some practical exercise to get familiar with the jUnit framework. I created a program that implements a String multiplier public String multiply(String number1, String number2) In order to test the multiplier method, I created a test suite consisting of the following test cases (with all the needed integer parsing, etc) @Test public class MultiplierTest { Multiplier multiplier = new Multiplier(); // Test for 2 positive integers assertEquals("Result", 5, multiplier.multiply("5", "1")); // Test for 1 positive integer and 0 assertEquals("Result", 0, multiplier.multiply("5", "0")); // Test for 1 positive and 1 negative integer assertEquals("Result", -1, multiplier.multiply("-1", "1")); // Test for 2 negative integers assertEquals("Result", 10, multiplier.multiply("-5", "-2")); // Test for 1 positive integer and 1 non number assertEquals("Result", , multiplier.multiply("x", "1")); // Test for 1 positive integer and 1 empty field assertEquals("Result", , multiplier.multiply("5", "")); // Test for 2 empty fields assertEquals("Result", , multiplier.multiply("", "")); In a similar fashion, I can create test cases involving boundary cases (considering numbers are int values) or even imaginary values. 1) But, what should be the expected value for the last 3 test cases above? (a special number indicating error?) 2) What additional test cases did I miss? 3) Is assertEquals() method enough for testing the multiplier method or do I need other methods like assertTrue(), assertFalse(), assertSame() etc 4) Is this the RIGHT way to go about developing test cases? How am I "exactly" benefiting from this exercise? 5)What should be the ideal way to test the multiplier method? I am pretty clueless here. If anyone can help answer these queries I'd greatly appreciate it. Thank you.

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  • Java Collections and Garbage Collector

    - by Anth0
    A little question regarding performance in a Java web app. Let's assume I have a List<Rubrique> listRubriques with ten Rubrique objects. A Rubrique contains one list of products (List<product> listProducts) and one list of clients (List<Client> listClients). What exactly happens in memory if I do this: listRubriques.clear(); listRubriques = null; My point of view would be that, since listRubriques is empty, all my objects previously referenced by this list (including listProducts and listClients) will be garbage collected pretty soon. But since Collection in Java are a little bit tricky and since I have quite performance issues with my app i'm asking the question :) edit : let's assume now that my Client object contains a List<Client>. Therefore, I have kind of a circular reference between my objects. What would happen then if my listRubrique is set to null? This time, my point of view would be that my Client objects will become "unreachable" and might create a memory leak?

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