Search Results

Search found 813 results on 33 pages for 'concurrency'.

Page 27/33 | < Previous Page | 23 24 25 26 27 28 29 30 31 32 33  | Next Page >

• Tips for measuring the parallelism speed-up in multi-core development.

  - by fnCzar

  I have read many of the good questions and answers around multi-core programming how-tos etc. I am familiar with concurrency, IPC, MPI etc but what I need is advice on how to measure speed-up which will help in making a business case of spending the time to write such code. Please don't answer with "well run it with single-core code then multi-core code and figure out the difference". This is neither a scientific nor a reliable way to measure performance improvement. If you know of tools that will do some of the heavy lifting please mention them. Answers pertaining to methodology will be more fitting but listing tools is ok as well.

  Read the article

• When is porting data from MySQL to CouchDB NOT advisable? Seeking cautionary tales

  - by dan

  I've dabbled in CouchDB and I have pretty good MySQL experience. I've also created one production application that uses both. I like MySQL but I've run into scaling/concurrency issues with MySQL that CouchDB advertises itself as a general solution for. The problem is that I have MySQL based applications that are pretty huge, and I don't really know whether it would be a good idea or not to try to port them over to a CouchDB datastore. I don't want to put in a lot of time and effort only to find out that my application is really not a good fit for CouchDB. Is there any sort of informed consensus on when porting a MySQL based app to CouchDB is NOT advisable? Any cautionary tales? I think CouchDB is really cool and want to use it more. I'd also like to know ahead of time what specific types of data querying scenarios CouchDB is really not good for, or if CouchDB can really replace MySQL for all the applications I create going forward.

  Read the article

• Is MS Access still the most efficient RAD tool for small-scale custom apps?

  - by FastAl

  Of the many other development tools I've used, nothing holds a candle to the 'Functionality to Development Effort' ratio of MS Access. The reason I am asking is that I have been out of the language selection process for a few years, working on a large .Net system, and am only anecdotally familiar with the latest development tools outside the .Net world. I'm well aware of the limitations of Access, but for a limited concurrency (usually only 1 user at a time), small business, custom app, has anybody found a comparable end-to-end solution or combination that comes close? It doesn't have to be free, open source, or even Windows based. It just has to allow the same speed of development and maintenance, and maybe even provide some additional amenities like seamless autointegration with a server-based DB Engine (like Access does with its own 'Jet' dbms), better web support, and a file format more compatible with source control. I don't want to miss out on anything. Please share your development experience with your suggestions. Thanks.

  Read the article

• Is Microsoft CCR gaining any traction?

  - by spender

  Microsoft's Concurrency and Coordination Runtime quite literally saved a project that was running into major issues with deadlocking. Since then I find that I use it more and more frequently for almost anything that requires asynchronous coding producing results that run lighter and faster than before. I can honestly state that it has transformed the way I think about multithread/multicore dev. Despite my personal love for CCR, there appears to be very little buzz surrounding it on the web and was wondering if anyone can offer any reason for this. Are there better alternatives, or is it a lack of promotion from MS, or are people simply happy with the existing tools?

  Read the article

• How to create unique user key

  - by Grayson Mitchell

  Scenario: I have a fairly generic table (Data), that has an identity column. The data in this table is grouped (lets say by city). The users need an identifier in order for printing on paper forms, etc. The users can only access their cites data, so if they use the identity column for this purpose they will see odd numbers (e.g. a 'New York' user might see 1,37,2028... as the listed keys. Idealy they would see 1,2,3... (or something similar) The problem of course is concurrency, this being a web application you can't just have something like: UserId = Select Count(*)+1 from Data Where City='New York' Has anyone come up with any cunning ways around this problem?

  Read the article

• How should flushing be handled in a doctrine EntityManager instance shared across different services in symfony2?

  - by Jbm

  I have defined several services in symfony 2 which persist changes to the database. These services have the doctrine instance as one of their dependencies: a.given.service: class: Acme\TestBundle\Service\AGivenService arguments: [@doctrine] If I have two different services and both of them persist objects through the EntityManager, which is obtained like this from the doctrine instance: $em = $doctrine->getEntityManager(); Would all services always share the same EntityManager? If so, how should I handle flushing if I wanted to handle all the changes in a single transaction? I have checked this: http://docs.doctrine-project.org/projects/doctrine-orm/en/2.0.x/reference/transactions-and-concurrency.html and it explains how to handle different transactions in a request, but I want to achieve the opposite, which is having different changes in different services handled as a single transaction. Is there a better approach to handle multiple changes in different services? For now my best bet is having a front-end service in charge of calling the other services and doing the flushing afterwards. Backend services would persist objects but would not do any flushing.

  Read the article

• When is BIG, big enough for a database?

  - by David ???

  I'm developing a Java application that has performance at its core. I have a list of some 40,000 "final" objects, i.e., I have an initialization input data of 40,000 vectors. This data is unchanged throughout the program's run. I am always preforming lookups against a single ID property to retrieve the proper vectors. Currently I am using a HashMap over a sub-sample of a 1,000 vectors, but I'm not sure it will scale to production. When is BIG, actually big enough for a use of DB? One more thing, an SQLite DB is a viable option as no concurrency is involved, so I guess the "threshold" for db use, is perhaps lower.

  Read the article

• Configuring jdbc-pool (tomcat 7)

  - by john

  i'm having some problems with tomcat 7 for configuring jdbc-pool : i`ve tried to follow this example: http://www.tomcatexpert.com/blog/2010/04/01/configuring-jdbc-pool-high-concurrency so i have: conf/server.xml <GlobalNamingResources> <Resource type="javax.sql.DataSource" name="jdbc/DB" factory="org.apache.tomcat.jdbc.pool.DataSourceFactory" driverClassName="com.mysql.jdbc.Driver" url="jdbc:mysql://localhost:3306/mydb" username="user" password="password" /> </GlobalNamingResources> conf/context.xml <Context> <ResourceLink type="javax.sql.DataSource" name="jdbc/LocalDB" global="jdbc/DB" /> <Context> and when i try to do this: Context initContext = new InitialContext(); Context envContext = (Context)initContext.lookup("java:/comp/env"); DataSource datasource = (DataSource)envContext.lookup("jdbc/LocalDB"); Connection con = datasource.getConnection(); i keep getting this error: javax.naming.NameNotFoundException: Name jdbc is not bound in this Context at org.apache.naming.NamingContext.lookup(NamingContext.java:803) at org.apache.naming.NamingContext.lookup(NamingContext.java:159) pls help tnx

  Read the article

• Mysql with innodb and serializable transaction does not (always) lock rows

  - by Tobias G.

  Hello, I have a transaction with a SELECT and possible INSERT. For concurrency reasons, I added FOR UPDATE to the SELECT. To prevent phantom rows, I'm using the SERIALIZABLE transaction isolation level. This all works fine when there are any rows in the table, but not if the table is empty. When the table is empty, the SELECT FOR UPDATE does not do any (exclusive) locking and a concurrent thread/process can issue the same SELECT FOR UPDATE without being locked. CREATE TABLE t ( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, display_order INT ) ENGINE = InnoDB; SET TRANSACTION ISOLATION LEVEL SERIALIZABLE; START TRANSACTION; SELECT COALESCE(MAX(display_order), 0) + 1 from t FOR UPDATE; .. This concept works as expected with SQL Server, but not with MySQL. Any ideas on what I'm doing wrong? EDIT Adding an index on display_order does not change the behavior.

  Read the article

• Java Spotlight Episode 139: Mark Heckler and José Pereda on JES based Energy Monitoring @MkHeck @JPeredaDnr

  - by Roger Brinkley

  Interview with Mark Heckler and José Pereda on using JavaSE Embedded with the Java Embedded Suite on a RaspberryPI along with a JavaFX client to monitor an energy production system and their JavaOne Tutorial- Java Embedded EXTREME MASHUPS: Building self-powering sensor nets for the IoT Right-click or Control-click to download this MP3 file. You can also subscribe to the Java Spotlight Podcast Feed to get the latest podcast automatically. If you use iTunes you can open iTunes and subscribe with this link: Java Spotlight Podcast in iTunes. Show Notes News Java Virtual Developer Day Session Videos Available JavaFX Maven Plugin 2.0 Released JavaFX Scene Builder 1.1 build b28 FXForm 2 release 0.2.2 OpenJDK8/Zero cross compile build for Foundation model HSAIL-based GPU offload: the Quest for Java Performance Begins Progress on Moving to Gradle Java EE 7 Launch Keynote Replay Java EE 7 Technical Breakouts Replay Java EE 7 support in NetBeans 7.3.1 Java EE 7 support in Eclipse 4.3 Java Magazine - May/June Events Jul 16-19, Uberconf, Denver, USA Jul 22-24, JavaOne Shanghai, China Jul 29-31, JVM Language Summit, Santa Clara Sep 11-12, JavaZone, Oslo, Norway Sep 19-20, Strange Loop, St. Louis Sep 22-26 JavaOne San Francisco 2013, USA Feature Interview Mark Heckler is an Oracle Corporation Java/Middleware/Core Tech Engineer with development experience in numerous environments. He has worked for and with key players in the manufacturing, emerging markets, retail, medical, telecom, and financial industries to develop and deliver critical capabilities on time and on budget. Currently, he works primarily with large government customers using Java throughout the stack and across the enterprise. He also participates in open-source development at every opportunity, being a JFXtras project committer and developer of DialogFX, MonologFX, and various other projects. When Mark isn't working with Java, he enjoys writing about his experiences at the Java Jungle website (https://blogs.oracle.com/javajungle/) and on Twitter (@MkHeck). José Pereda is a Structural Engineer working in the School of Engineers in the University of Valladolid in Spain for more than 15 years, and his passion is related to applying programming to solve real problems. Being involved with Java since 1999, José shares his time between JavaFX and the Embedded world, developing commercial applications and open source projects (https://github.com/jperedadnr), and blogging (http://jperedadnr.blogspot.com.es/) or tweeting (@JPeredaDnr) of both. What’s Cool AquaFX 0.1 - Mac OS X skin for JavaFX by Claudine Zillmann DromblerFX adds a docking framework Part 2 of Gerrit’s taming the Nashorn for writing JavaFX apps in Javascript Tool from mihosoft called JSelect for quickly switching JDKs Apache Maven Javadoc Plugin 2.9.1 Released Proposal: Java Concurrency Stress tests (jcstress) Slide-free Code-driven session at SV JUG JavaOne approvals/rejects gone out

  Read the article

• Java Space on Parleys

  - by Yolande Poirier

  Now available! A great selection of JavaOne 2010 and JVM Language Summit 2010 sessions as well as Oracle Technology Network TechCasts on the new Java Space on Parleys website. Oracle partnered with Stephan Janssen, founder of Parleys to make this happen. Parleys website offers a user friendly experience to view online content. You can download some of the talks to your desktop or watch them on the go on mobile devices. The current selection is a well of expertise from top Java luminaries and Oracle experts. JavaOne 2010 sessions: ·        Best practices for signing code by Sean Mullan   ·        Building software using rich client platforms by Rickard Thulin ·        Developing beyond the component libraries by Ryan Cuprak ·        Java API for keyhole markup language by Florian Bachmann ·        Avoiding common user experience anti-patterns by Burk Hufnagel ·        Accelerating Java workloads via GPUs by Gary Frost JVM Languages Summit 2010 sessions: ·      Mixed language project compilation in Eclipse by Andy Clement  ·      Gathering the threads by John Rose  ·      LINQ: language features for concurrency by Neal Gafter  ·      Improvements in OpenJDK useful for JVM languages by Eric Caspole  ·      Symmetric Multilanguage - VM Architecture by Oleg Pliss  Special interviews with Oracle experts on product innovations: ·      Ludovic Champenois, Java EE architect on Glassfish 3.1 and Java EE. ·      John Jullion-Ceccarelli and Martin Ryzl on NetBeans IDE 6.9 You can chose to listen to a section of talks using the agenda view and search for related content while watching a presentation.  Enjoy the Java content and vote on it! 

  Read the article

• JCP.Next - Early Adopters of JCP 2.8

  - by Heather VanCura

  JCP.Next is a series of three JSRs (JSR 348, JSR 355 and JSR 358), to be defined through the JCP process itself, with the JCP Executive Committee serving as the Expert Group. The proposed JSRs will modify the JCP's processes  - the Process Document and Java Specification Participation Agreement (JSPA) and will apply to all new JSRs for all Java platforms.   The first - JCP.next.1, or more formally JSR 348, Towards a new version of the Java Community Process - was completed and put into effect in October 2011 as JCP 2.8. This focused on a small number of simple but important changes to make our process more transparent and to enable broader participation. We're already seeing the benefits of these changes as new and existing JSRs adopt the new requirements. The second - JSR 355, Executive Committee Merge, is also Final. You can read the JCP 2.9 Process Document .  As part of the JSR 355 Final Release, the JCP Executive Committee published revisions to the JCP Process Document (version 2.9) and the EC Standing Rules (version 2.2).  The changes went into effect following the 2012 EC Elections in November. The third JSR 358, A major revision of the Java Community Process was submitted in June 2012.  This JSR will modify the Java Specification Participation Agreement (JSPA) as well as the Process Document, and will tackle a large number of complex issues, many of them postponed from JSR 348. For these reasons, the JCP EC (acting as the Expert Group for this JSR), expects to spend a considerable amount of time working on. The JSPA is defined by the JCP as "a one-year, renewable agreement between the Member and Oracle. The success of the Java community depends upon an open and transparent JCP program.  JSR 358, A major revision of the Java Community Process, is now in process and can be followed on java.net. The following JSRs and Spec Leads were the early adopters of JCP 2.8, who voluntarily migrated their JSRs from JCP 2.x to JCP 2.8 or above.  More candidates for 2012 JCP Star Spec Leads! JSR 236, Concurrency Utilities for Java EE (Anthony Lai/Oracle), migrated April 2012 JSR 308, Annotations on Java Types (Michael Ernst, Alex Buckley/Oracle), migrated September 2012 JSR 335, Lambda Expressions for the Java Programming Language (Brian Goetz/Oracle), migrated October 2012 JSR 337, Java SE 8 Release Contents (Mark Reinhold/Oracle) – EG Formation, migrated September 2012 JSR 338, Java Persistence 2.1 (Linda DeMichiel/Oracle), migrated January 2012 JSR 339, JAX-RS 2.0: The Java API for RESTful Web Services (Santiago Pericas-Geertsen, Marek Potociar/Oracle), migrated July 2012 JSR 340, Java Servlet 3.1 Specification (Shing Wai Chan, Rajiv Mordani/Oracle), migrated August 2012 JSR 341, Expression Language 3.0 (Kin-man Chung/Oracle), migrated August 2012 JSR 343, Java Message Service 2.0 (Nigel Deakin/Oracle), migrated March 2012 JSR 344, JavaServer Faces 2.2 (Ed Burns/Oracle), migrated September 2012 JSR 345, Enterprise JavaBeans 3.2 (Marina Vatkina/Oracle), migrated February 2012 JSR 346, Contexts and Dependency Injection for Java EE 1.1 (Pete Muir/RedHat) – migrated December 2011

  Read the article

• Unification of TPL TaskScheduler and RX IScheduler

  - by JoshReuben

  using System; using System.Collections.Generic; using System.Reactive.Concurrency; using System.Security; using System.Threading; using System.Threading.Tasks; using System.Windows.Threading; namespace TPLRXSchedulerIntegration { public class MyScheduler :TaskScheduler, IScheduler     { private readonly Dispatcher _dispatcher; private readonly DispatcherScheduler _rxDispatcherScheduler; //private readonly TaskScheduler _tplDispatcherScheduler; private readonly SynchronizationContext _synchronizationContext; public MyScheduler(Dispatcher dispatcher)         {             _dispatcher = dispatcher;             _rxDispatcherScheduler = new DispatcherScheduler(dispatcher); //_tplDispatcherScheduler = FromCurrentSynchronizationContext();             _synchronizationContext = SynchronizationContext.Current;         }         #region RX public DateTimeOffset Now         { get { return _rxDispatcherScheduler.Now; }         } public IDisposable Schedule<TState>(TState state, DateTimeOffset dueTime, Func<IScheduler, TState, IDisposable> action)         { return _rxDispatcherScheduler.Schedule(state, dueTime, action);         } public IDisposable Schedule<TState>(TState state, TimeSpan dueTime, Func<IScheduler, TState, IDisposable> action)         { return _rxDispatcherScheduler.Schedule(state, dueTime, action);         } public IDisposable Schedule<TState>(TState state, Func<IScheduler, TState, IDisposable> action)         { return _rxDispatcherScheduler.Schedule(state, action);         }         #endregion         #region TPL /// Simply posts the tasks to be executed on the associated SynchronizationContext         [SecurityCritical] protected override void QueueTask(Task task)         {             _dispatcher.BeginInvoke((Action)(() => TryExecuteTask(task))); //TryExecuteTaskInline(task,false); //task.Start(_tplDispatcherScheduler); //m_synchronizationContext.Post(s_postCallback, (object)task);         } /// The task will be executed inline only if the call happens within the associated SynchronizationContext         [SecurityCritical] protected override bool TryExecuteTaskInline(Task task, bool taskWasPreviouslyQueued)         { if (SynchronizationContext.Current != _synchronizationContext)             { SynchronizationContext.SetSynchronizationContext(_synchronizationContext);             } return TryExecuteTask(task);         } // not implemented         [SecurityCritical] protected override IEnumerable<Task> GetScheduledTasks()         { return null;         } /// Implementes the MaximumConcurrencyLevel property for this scheduler class. /// By default it returns 1, because a <see cref="T:System.Threading.SynchronizationContext"/> based /// scheduler only supports execution on a single thread. public override Int32 MaximumConcurrencyLevel         { get             { return 1;             }         } //// preallocated SendOrPostCallback delegate //private static SendOrPostCallback s_postCallback = new SendOrPostCallback(PostCallback); //// this is where the actual task invocation occures //private static void PostCallback(object obj) //{ //    Task task = (Task) obj; //    // calling ExecuteEntry with double execute check enabled because a user implemented SynchronizationContext could be buggy //    task.ExecuteEntry(true); //}         #endregion     } }     What Design Pattern did I use here?

  Read the article

• JSR 360 and JSR 361: A Big Leap for Java ME 8

  - by terrencebarr

  It might have gone unnoticed to some, but Java ME took a big leap forward a couple of weeks ago with the filing of two new JSRs: JSR 360: “Connected Limited Device Configuration 8″ (aka CLDC 8) JSR 361: “Java ME Embedded Profile” (aka ME EP) Together, these two JSRs will significantly update, enhance, and modernize the Java ME platform, and specifically small embedded Java, with a host of new features and functionality. JSR 360 – Connected Limited Device Configuration 8 CLDC 8 is based on JSR 139 (CLDC 1.1) and updates the core Java ME VM, language support, libraries, and features to be aligned with Java SE 8. This will include: VM updated to comply with the JVM language specification version 2 Support for SE 7/8 language features like Generics, Assertions, Annotations, Try-with-Resources, and more New libraries such as Collections, NIO subset, Logging API subset A consolidated and enhanced Generic Connection Framework for multi-protocol I/O With CLDC 8, Java ME and Java SE are entering their next phase of alignment – making Java the only technology today that truly scales application development, code re-use, and tooling across the whole range of IT platforms, from small embedded to large enterprise. JSR 361 – Java ME Embedded Profile ME EP is based on JSR 228 (IMP-NG) and updates the specification in key areas to provide a powerful and flexible application environment for small embedded Java platforms, building on the features of CLDC 8:  A new, lightweight component and services model Shared libraries Multi-application concurrency, inter-application communication, and event system Application management API optionality, to address low-footprint use cases With ME EP, application developers will have a modern application environment which allows development and deployment of  modular, robust, sophisticated, and footprint-optimized solutions for a wide range of embedded use cases and devices. Summary While these JSRs are still under development, it’s clear that there are exciting new times ahead for Java ME – turning into a serious application platform while maintaining the focus on resource-constrained devices to address the expected explosion of small, smart, and connected embedded platforms. To learn more, click on the above links for JSR 360 and JSR 361. Or review the JavaOne 2012 online presentations on the topic: CON11300: Expanding the reach of the Java ME Platform CON5943: Java ME 8 Service Platform And stay tuned for more in this space! Cheers, – Terrence Filed under: Mobile & Embedded Tagged: "jsr 360", "jsr 361", "me 8", embedded, Embedded Java, JCP

  Read the article

• JSR 360 and JSR 361: A Big Leap for Java ME 8

  - by terrencebarr

  It might have gone unnoticed to some, but Java ME took a big leap forward a couple of weeks ago with the filing of two new JSRs: JSR 360: “Connected Limited Device Configuration 8″ (aka CLDC 8) JSR 361: “Java ME Embedded Profile” (aka ME EP) Together, these two JSRs will significantly update, enhance, and modernize the Java ME platform, and specifically small embedded Java, with a host of new features and functionality. JSR 360 – Connected Limited Device Configuration 8 CLDC 8 is based on JSR 139 (CLDC 1.1) and updates the core Java ME VM, language support, libraries, and features to be aligned with Java SE 8. This will include: VM updated to comply with the JVM language specification version 2 Support for SE 7/8 language features like Generics, Assertions, Annotations, Try-with-Resources, and more New libraries such as Collections, NIO subset, Logging API subset A consolidated and enhanced Generic Connection Framework for multi-protocol I/O With CLDC 8, Java ME and Java SE are entering their next phase of alignment – making Java the only technology today that truly scales application development, code re-use, and tooling across the whole range of IT platforms, from small embedded to large enterprise. JSR 361 – Java ME Embedded Profile ME EP is based on JSR 228 (IMP-NG) and updates the specification in key areas to provide a powerful and flexible application environment for small embedded Java platforms, building on the features of CLDC 8:  A new, lightweight component and services model Shared libraries Multi-application concurrency, inter-application communication, and event system Application management API optionality, to address low-footprint use cases With ME EP, application developers will have a modern application environment which allows development and deployment of  modular, robust, sophisticated, and footprint-optimized solutions for a wide range of embedded use cases and devices. Summary While these JSRs are still under development, it’s clear that there are exciting new times ahead for Java ME – turning into a serious application platform while maintaining the focus on resource-constrained devices to address the expected explosion of small, smart, and connected embedded platforms. To learn more, click on the above links for JSR 360 and JSR 361. Or review the JavaOne 2012 online presentations on the topic: CON11300: Expanding the reach of the Java ME Platform CON5943: Java ME 8 Service Platform And stay tuned for more in this space! Cheers, – Terrence Filed under: Mobile & Embedded Tagged: "jsr 360", "jsr 361", "me 8", embedded, Embedded Java, JCP

  Read the article

• Back-sliding into Unmanaged Code

  - by Laila

  It is difficult to write about Microsoft's ambivalence to .NET without mentioning clichés about dog food.  In case you've been away a long time, you'll remember that Microsoft surprised everyone with the speed and energy with which it introduced and evangelised the .NET Framework for managed code. There was good reason for this. Once it became obvious to all that it had sleepwalked into third place as a provider of development languages, behind Borland and Sun, it reacted quickly to attract the best talent in the industry to produce a windows version of the Java runtime, with Bounds-checking, Automatic Garbage collection, structures exception handling and common data types. To develop applications for this managed runtime, it produced several excellent languages, and more are being provided. The only thing Microsoft ever got wrong was to give it a stupid name. The logical step for Microsoft would be to base the entire operating system on the .NET framework, and to re-engineer its own applications. In 2002, Bill Gates, then Microsoft Chairman and Chief Software Architect said about their plans for .NET, "This is a long-term approach. These things don't happen overnight." Now, eight years later, we're still waiting for signs of the 'long-term approach'. Microsoft's vision of an entirely managed operating system has subsided since the Vista fiasco, but stays alive yet dormant as Midori, still being developed by Microsoft Research. This is an Internet-centric fork of the singularity operating system, a research project started in 2003 to build a highly-dependable operating system in which the kernel, device drivers, and applications are all written in managed code. Midori is predicated on the prevalence of connected systems, with provisions for distributed concurrency where application components exist 'in the cloud', and supports a programming model that can tolerate cancellation, intermittent connectivity and latency. It features an entirely new security model that sandboxes applications for increased security. So have Microsoft converted its existing applications to the .NET framework? It seems not. What Windows applications can run on Mono? Very few, it seems. We all thought that .NET spelt the end of DLL Hell and the need for COM interop, but it looks as if Bill Gates' idea of 'not overnight' might stretch to a decade or more. The Operating System has shown only minimal signs of migrating to .NET. Even where the use of .NET has come to dominate, when used for server applications with IIS, IIS itself is still entirely developed in unmanaged code. This is an irritation to Microsoft's greatest supporters who committed themselves fully to the NET framework, only to find parts of the Ambivalent Microsoft Empire quietly backsliding into unmanaged code and the awful C++. It is a strategic mistake that the invigorated Apple didn't make with the Mac OS X Architecture. Cheers, Laila

  Read the article

• Questions re: Eclipse Jobs API

  - by BenCole

  Similar to http://stackoverflow.com/questions/8738160/eclipse-jobs-api-for-a-stand-alone-swing-project This question mentions the Jobs API from the Eclipse IDE: ...The disadvantage of the pre-3.0 approach was that the user had to wait until an operation completed before the UI became responsive again. The UI still provided the user the ability to cancel the currently running operation but no other work could be done until the operation completed. Some operations were performed in the background (resource decoration and JDT file indexing are two such examples) but these operations were restricted in the sense that they could not modify the workspace. If a background operation did try to modify the workspace, the UI thread would be blocked if the user explicitly performed an operation that modified the workspace and, even worse, the user would not be able to cancel the operation. A further complication with concurrency was that the interaction between the independent locking mechanisms of different plug-ins often resulted in deadlock situations. Because of the independent nature of the locks, there was no way for Eclipse to recover from the deadlock, which forced users to kill the application... ...The functionality provided by the workspace locking mechanism can be broken down into the following three aspects: Resource locking to ensure multiple operations did not concurrently modify the same resource Resource change batching to ensure UI stability during an operation Identification of an appropriate time to perform incremental building With the introduction of the Jobs API, these areas have been divided into separate mechanisms and a few additional facilities have been added. The following list summarizes the facilities added. Job class: support for performing operations or other work in the background. ISchedulingRule interface: support for determining which jobs can run concurrently. WorkspaceJob and two IWorkspace#run() methods: support for batching of delta change notifications. Background auto-build: running of incremental build at a time when no other running operations are affecting resources. ILock interface: support for deadlock detection and recovery. Job properties for configuring user feedback for jobs run in the background. The rest of this article provides examples of how to use the above-mentioned facilities... In regards to above API, is this an implementation of a particular design pattern? Which one?

  Read the article

• Design pattern for an ASP.NET project using Entity Framework

  - by MPelletier

  I'm building a website in ASP.NET (Web Forms) on top of an engine with business rules (which basically resides in a separate DLL), connected to a database mapped with Entity Framework (in a 3rd, separate project). I designed the Engine first, which has an Entity Framework context, and then went on to work on the website, which presents various reports. I believe I made a terrible design mistake in that the website has its own context (which sounded normal at first). I present this mockup of the engine and a report page's code behind: Engine (in separate DLL): public Engine { DatabaseEntities _engineContext; public Engine() { // Connection string and procedure managed in DB layer _engineContext = DatabaseEntities.Connect(); } public ChangeSomeEntity(SomeEntity someEntity, int newValue) { //Suppose there's some validation too, non trivial stuff SomeEntity.Value = newValue; _engineContext.SaveChanges(); } } And report: public partial class MyReport : Page { Engine _engine; DatabaseEntities _webpageContext; public MyReport() { _engine = new Engine(); _databaseContext = DatabaseEntities.Connect(); } public void ChangeSomeEntityButton_Clicked(object sender, EventArgs e) { SomeEntity someEntity; //Wrong way: //Get the entity from the webpage context someEntity = _webpageContext.SomeEntities.Single(s => s.Id == SomeEntityId); //Send the entity from _webpageContext to the engine _engine.ChangeSomeEntity(someEntity, SomeEntityNewValue); // <- oops, conflict of context //Right(?) way: //Get the entity from the engine context someEntity = _engine.GetSomeEntity(SomeEntityId); //undefined above //Send the entity from the engine's context to the engine _engine.ChangeSomeEntity(someEntity, SomeEntityNewValue); // <- oops, conflict of context } } Because the webpage has its own context, giving the Engine an entity from a different context will cause an error. I happen to know not to do that, to only give the Engine entities from its own context. But this is a very error-prone design. I see the error of my ways now. I just don't know the right path. I'm considering: Creating the connection in the Engine and passing it off to the webpage. Always instantiate an Engine, make its context accessible from a property, sharing it. Possible problems: other conflicts? Slow? Concurrency issues if I want to expand to AJAX? Creating the connection from the webpage and passing it off to the Engine (I believe that's dependency injection?) Only talking through ID's. Creates redundancy, not always practical, sounds archaic. But at the same time, I already recuperate stuff from the page as ID's that I need to fetch anyways. What would be best compromise here for safety, ease-of-use and understanding, stability, and speed?

  Read the article

• JUDCon 2013 Trip Report

  - by reza_rahman

  JUDCon (JBoss Users and Developers Conference) 2013 was held in historic Boston on June 9-11 at the Hynes Convention Center. JUDCon is the largest get together for the JBoss community, has gone global in recent years but has it's roots in Boston. The JBoss folks graciously accepted a Java EE 7 talk from me and actually referenced my talk in their own sessions. I am proud to say this is my third time speaking at JUDCon/the Red Hat Summit over the years (this was the first time on behalf of Oracle). I had great company with many of the rock stars of the JBoss ecosystem speaking such as Lincoln Baxter, Jay Balunas, Gavin King, Mark Proctor, Andrew Lee Rubinger, Emmanuel Bernard and Pete Muir. Notably missing from JUDCon were Bill Burke, Burr Sutter, Aslak Knutsen and Dan Allen. Topics included Java EE, Forge, Arquillian, AeroGear, OpenShift, WildFly, Errai/GWT, NoSQL, Drools, jBPM, OpenJDK, Apache Camel and JBoss Tools/Eclipse. My session titled "JavaEE.Next(): Java EE 7, 8, and Beyond" went very well and it was a full house. This is our main talk covering the changes in JMS 2, the Java API for WebSocket (JSR 356), the Java API for JSON Processing (JSON-P), JAX-RS 2, JPA 2.1, JTA 1.2, JSF 2.2, Java Batch, Bean Validation 1.1, Java EE Concurrency and the rest of the APIs in Java EE 7. I also briefly talked about the possibilities for Java EE 8. The slides for the talk are here: JavaEE.Next(): Java EE 7, 8, and Beyond from reza_rahman Besides presenting my talk, it was great to catch up with the JBoss gang and attend a few interesting sessions. On Sunday night I went to one of my favorite hangouts in Boston - the exalted Middle East Club as Rolling Stone refers to it (other cool spots in an otherwise pretty boring town is "the Church"). As contradictory as it might sound to the uninitiated, the Middle East Club is possibly the best place in Boston to simultaneously get great Middle Eastern (primarily Lebanese) food and great underground metal. For folks with a bit more exposure, this is probably not contradictory at all given bands like Acrassicauda and documentaries like Heavy Metal in Baghdad. Luckily for me they were featuring a few local Thrash metal bands from the greater Boston area. It wasn't too bad considering it was primarily amateur twenty-something guys (although I'm not sure I'm a qualified critic any more since I all but stopped playing about at that age). It's great Boston has the Middle East as an incubator to keep the rock, metal, folk, jazz, blues and indie scene alive. I definitely enjoyed JUDCon/Boston and hope to be part of the conference next year again.

  Read the article

• C++ Accelerated Massive Parallelism

  - by Daniel Moth

  At AMD's Fusion conference Herb Sutter announced in his keynote session a technology that our team has been working on that we call C++ Accelerated Massive Parallelism (C++ AMP) and during the keynote I showed a brief demo of an app built with our technology. After the keynote, I go deeper into the technology in my breakout session. If you read both those abstracts, you'll get some information about what C++ AMP is, without being too explicit since we published the abstracts before the technology was announced. You can find the official online announcement at Soma's blog post. Here, I just wanted to capture the key points about C++ AMP that can serve as an introduction and an FAQ. So, in no particular order… C++ AMP lowers the barrier to entry for heterogeneous hardware programmability and brings performance to the mainstream, without sacrificing developer productivity or solution portability. is designed not only to help you address today's massively parallel hardware (i.e. GPUs and APUs), but it also future proofs your code investments with a forward looking design. is part of Visual C++. You don't need to use a different compiler or learn different syntax. is modern C++. Not C or some other derivative. is integrated and supported fully in Visual Studio vNext. Editing, building, debugging, profiling and all the other goodness of Visual Studio work well with C++ AMP. provides an STL-like library as part of the existing concurrency namespace and delivered in the new amp.h header file. makes it extremely easy to work with large multi-dimensional data on heterogeneous hardware; in a manner that exposes parallelization. introduces only one core C++ language extension. builds on DirectX (and DirectCompute in particular) which offers a great hardware abstraction layer that is ubiquitous and reliable. The architecture is such, that this point can be thought of as an implementation detail that does not surface to the API layer. Stay tuned on my blog for more over the coming months where I will switch from just talking about C++ AMP to showing you how to use the API with code examples… Comments about this post welcome at the original blog.

  Read the article

• Best Creational Pattern for loggers in a multi-threaded system?

  - by Dipan Mehta

  This is a follow up question on my past questions : Concurrency pattern of logger in multithreaded application As suggested by others, I am putting this question separately. As the learning from the last question. In a multi-threaded environment, the logger should be made thread safe and probably asynchronous (where in messages are queued while a background thread does writing releasing the requesting object thread). The logger could be signleton or it can be a per-group logger which is a generalization of the above. Now, the question that arise is how does logger should be assigned to the object? There are two options I can think of: 1. Object requesting for the logger: Should each of the object call some global API such as get_logger()? Such an API returns "the" singleton or the group logger. However, I feel this involves assumption about the Application environment to implement the logger -which I think is some kind of coupling. If the same object needs to be used by other application - this new application also need to implement such a method. 2. Assign logger through some known API The other alternative approach is to create a kind of virtual class which is implemented by application based on App's own structure and assign the object sometime in the constructor. This is more generalized method. Unfortunately, when there are so many objects - and rather a tree of objects passing on the logger objects to each level is quite messy. My question is there a better way to do this? If you need to pick any one of the above, which approach is would you pick and why? Other questions remain open about how to configure them: How do objects' names or ID are assigned so that will be used for printing on the log messages (as the module names) How do these objects find the appropriate properties (such as log levels, and other such parameters) In the first approach, the central API needs to deal with all this varieties. In the second approach - there needs to be additional work. Hence, I want to understand from the real experience of people, as to how to write logger effectively in such an environment.

  Read the article

• Is there a pedagogical game engine?

  - by K.G.

  I'm looking for a book, website, or other resource that gives modern 3D game engines the same treatment as Operating Systems: Design and Implementation gave operating systems. I have read Jason Gregory's Game Engine Architecture, which I enjoyed. However, by intent the author treated components of the architecture as atomic units, whereas what I'm interested in is the plumbing between those units that makes a coherent whole out of ideally loosely coupled parts. In books such as these, one usually reads that "that's academic," but that's the point! I have also read Julian Gold's Object-oriented Game Development, which likewise was good, but I feel is beginning to show its age. Since even mobile platforms these days are multicore and have fast video memory, those kinds of things (concurrency, display item buffering) would ideally be covered. There are other resources, such as the Doom 3 source code, which is highly instructive for its being a shipped product. The problem with those is as follows: float Q_rsqrt( float number ) { long i; float x2, y; const float threehalfs = 1.5F; x2 = number * 0.5F; y = number; i = * ( long * ) &y; // evil floating point bit level hacking i = 0x5f3759df - ( i >> 1 ); // what the f***? y = * ( float * ) &i; y = y * ( threehalfs - ( x2 * y * y ) ); // 1st iteration // y = y * ( threehalfs - ( x2 * y * y ) ); // 2nd iteration, this can be removed return y; } To wit, while brilliant, this kind of source requires more enlightenment than I can usually muster upon first read. In summary, here's my white whale: For an adult reader with experience in programming. I wish I could save all the trees killed by every. Single. Game Programming book ever devoting the first two chapters to "Now just what is a variable anyway?" In C or C++, very preferably C++. Languages that are more concise are fantastic for teaching, except for when what you want to learn is how to cope with a verbose language. There is also the benefit of the guardrails that C++ doesn't provide, such as garbage collection. Platform agnostic. I'm sincerely afraid that this book is out there and it's Visual C++/DirectX oriented. I'm a Linux guy, and I'd do what it takes, but I would very much like to be able to use OpenGL. Thanks for everything! Before anyone gets on my case about it, Fast inverse square root was from Quake III Arena, not Doom 3!

  Read the article

• How granular should a command be in a CQ[R]S model?

  - by Aaronaught

  I'm considering a project to migrate part of our WCF-based SOA over to a service bus model (probably nServiceBus) and using some basic pub-sub to achieve Command-Query Separation. I'm not new to SOA, or even to service bus models, but I confess that until recently my concept of "separation" was limited to run-of-the-mill database mirroring and replication. Still, I'm attracted to the idea because it seems to provide all the benefits of an eventually-consistent system while sidestepping many of the obvious drawbacks (most notably the lack of proper transactional support). I've read a lot on the subject from Udi Dahan who is basically the guru on ESB architectures (at least in the Microsoft world), but one thing he says really puzzles me: As we get larger entities with more fields on them, we also get more actors working with those same entities, and the higher the likelihood that something will touch some attribute of them at any given time, increasing the number of concurrency conflicts. [...] A core element of CQRS is rethinking the design of the user interface to enable us to capture our users’ intent such that making a customer preferred is a different unit of work for the user than indicating that the customer has moved or that they’ve gotten married. Using an Excel-like UI for data changes doesn’t capture intent, as we saw above. -- Udi Dahan, Clarified CQRS From the perspective described in the quotation, it's hard to argue with that logic. But it seems to go against the grain with respect to SOAs. An SOA (and really services in general) are supposed to deal with coarse-grained messages so as to minimize network chatter - among many other benefits. I realize that network chatter is less of an issue when you've got highly-distributed systems with good message queuing and none of the baggage of RPC, but it doesn't seem wise to dismiss the issue entirely. Udi almost seems to be saying that every attribute change (i.e. field update) ought to be its own command, which is hard to imagine in the context of one user potentially updating hundreds or thousands of combined entities and attributes as it often is with a traditional web service. One batch update in SQL Server may take a fraction of a second given a good highly-parameterized query, table-valued parameter or bulk insert to a staging table; processing all of these updates one at a time is slow, slow, slow, and OLTP database hardware is the most expensive of all to scale up/out. Is there some way to reconcile these competing concerns? Am I thinking about it the wrong way? Does this problem have a well-known solution in the CQS/ESB world? If not, then how does one decide what the "right level" of granularity in a Command should be? Is there some "standard" one can use as a starting point - sort of like 3NF in databases - and only deviate when careful profiling suggests a potentially significant performance benefit? Or is this possibly one of those things that, despite several strong opinions being expressed by various experts, is really just a matter of opinion?

  Read the article

• "Hello World" in C++ AMP

  - by Daniel Moth

  Some say that the equivalent of "hello world" code in the data parallel world is matrix multiplication :) Below is the before C++ AMP and after C++ AMP code. For more on what it all means, watch the recording of my C++ AMP introduction (the example below is part of the session). void MatrixMultiply(vector<float>& vC, const vector<float>& vA, const vector<float>& vB, int M, int N, int W ) { for (int y = 0; y < M; y++) { for (int x = 0; x < N; x++) { float sum = 0; for(int i = 0; i < W; i++) { sum += vA[y * W + i] * vB[i * N + x]; } vC[y * N + x] = sum; } } } Change the function to use C++ AMP and hence offload the computation to the GPU, and now the calling code (which I am not showing) needs no changes and the overall operation gives you really nice speed up for large datasets…  #include <amp.h> using namespace concurrency; void MatrixMultiply(vector<float>& vC, const vector<float>& vA, const vector<float>& vB, int M, int N, int W ) { array_view<const float,2> a(M, W, vA); array_view<const float,2> b(W, N, vB); array_view<writeonly<float>,2> c(M, N, vC); parallel_for_each( c.grid, [=](index<2> idx) mutable restrict(direct3d) { float sum = 0; for(int i = 0; i < a.x; i++) { sum += a(idx.y, i) * b(i, idx.x); } c[idx] = sum; } ); } Again, you can understand the elements above, by using my C++ AMP presentation slides and recording… Stay tuned for more… Comments about this post welcome at the original blog.

  Read the article

• Java @Contented annotation to help reduce false sharing

  - by Dave

  See this posting by Aleksey Shipilev for details -- @Contended is something we've wanted for a long time. The JVM provides automatic layout and placement of fields. Usually it'll (a) sort fields by descending size to improve footprint, and (b) pack reference fields so the garbage collector can process a contiguous run of reference fields when tracing. @Contended gives the program a way to provide more explicit guidance with respect to concurrency and false sharing. Using this facility we can sequester hot frequently written shared fields away from other mostly read-only or cold fields. The simple rule is that read-sharing is cheap, and write-sharing is very expensive. We can also pack fields together that tend to be written together by the same thread at about the same time. More generally, we're trying to influence relative field placement to minimize coherency misses. Fields that are accessed closely together in time should be placed proximally in space to promote cache locality. That is, temporal locality should condition spatial locality. Fields accessed together in time should be nearby in space. That having been said, we have to be careful to avoid false sharing and excessive invalidation from coherence traffic. As such, we try to cluster or otherwise sequester fields that tend to written at approximately the same time by the same thread onto the same cache line. Note that there's a tension at play: if we try too hard to minimize single-threaded capacity misses then we can end up with excessive coherency misses running in a parallel environment. Theres no single optimal layout for both single-thread and multithreaded environments. And the ideal layout problem itself is NP-hard. Ideally, a JVM would employ hardware monitoring facilities to detect sharing behavior and change the layout on the fly. That's a bit difficult as we don't yet have the right plumbing to provide efficient and expedient information to the JVM. Hint: we need to disintermediate the OS and hypervisor. Another challenge is that raw field offsets are used in the unsafe facility, so we'd need to address that issue, possibly with an extra level of indirection. Finally, I'd like to be able to pack final fields together as well, as those are known to be read-only.

  Read the article

< Previous Page | 23 24 25 26 27 28 29 30 31 32 33  | Next Page >