Search Results

Search found 6694 results on 268 pages for 'wait states'.

Page 80/268 | < Previous Page | 76 77 78 79 80 81 82 83 84 85 86 87  | Next Page >

  • Cannot connect to google talk using empathy/pidgin after upgrading

    - by levesque
    I can't seem to be able to connect to google talk using either pidgin or empathy after upgrading to Ubuntu 10.10 (fresh install). I do not know why... empathy just writes "Connecting ..." forever and never connects. What can I do from there? Google talk's web interface works just fine for me so I doubt it is a firewall issue. EDIT: In fact sometimes it's able to connect (empathy), it just takes a LOOONG time (I'd say about 5 mins), longer than I am willing to wait. On the other hand, the web interface is able to connect in seconds.

    Read the article

  • Lego Sport Champions: Soccer – An 80s Style LEGO Video

    - by Asian Angel
    Are you a fan of LEGO and soccer? Then watch as these two teams use some fancy LEGO footwork to try and win the championship game in this nicely done retro-look video. Wait!! Is that player building a brick wall?? Lego Sport Champions: Soccer [YouTube] Latest Features How-To Geek ETC Have You Ever Wondered How Your Operating System Got Its Name? Should You Delete Windows 7 Service Pack Backup Files to Save Space? What Can Super Mario Teach Us About Graphics Technology? Windows 7 Service Pack 1 is Released: But Should You Install It? How To Make Hundreds of Complex Photo Edits in Seconds With Photoshop Actions How to Enable User-Specific Wireless Networks in Windows 7 Lego Sport Champions: Soccer – An 80s Style LEGO Video Access the Options for Your Favorite Extensions Easier in Firefox Don’t Sleep Keeps Your Windows Machine Awake DropSpace Syncs Android Files to Dropbox Field of Poppies Wallpaper The History Of Operating Systems [Infographic]

    Read the article

  • Operating systems theory -- using minimum number of semaphores

    - by stackuser
    This situation is prone to deadlock of processes in an operating system and I'd like to solve it with the minimum of semaphores. Basically there are three cooperating processes that all read data from the same input device. Each process, when it gets the input device, must read two consecutive data. I want to use mutual exclusion to do this. Semaphores should be used to synchronize: P1: P2: P3: input(a1,a2) input (b1,b2) input(c1,c2) Y=a1+c1 W=b2+c2 Z=a2+b1 Print (X) X=Z-Y+W The declaration and initialization that I think would work here are: semaphore s=1 sa1 = 0, sa2 = 0, sb1 = 0, sb2 = 0, sc1 = 0, sc2 = 0 I'm sure that any kernel programmers that happen on this can knock this out in a minute or 2. Diagram of cooperating Processes and one input device: It seems like P1 and P2 would start something like: wait(s) input (a1/b1, a2/b2) signal(s)

    Read the article

  • Speaking at Tech-Ed Europe Next Week

    - by Stephen Walther
    I’m going to Berlin! Next week, I’m giving talks at Tech-Ed Europe on two of my favorite topics: What's New in Microsoft ASP.NET Model-View-Controller ASP.NET Model-View-Controller (MVC) 2 introduces new features to make you more productive when building an ASP.NET MVC application. Templated helpers allow automatically associatiating edit and display elements with data types. Areas provide a means of dividing a large Web application into multiple projects. Data annotations allow attaching metadata attributes on a model to control validation. Microsoft ASP.NET AJAX: Taking AJAX to the Next Level Hear how ASP.NET AJAX 4.0 makes building pure client-side AJAX Web applications even easier, and watch us build an entire data-driven ASP.NET AJAX application from start to finish by taking advantage of only JavaScript, HTML pages, and Windows Communication Foundation (WCF) services. Also learn about new ASP.NET AJAX features including the DataView control, declarative templates, live client-side data binding, WCF, and REST integration.   The conference has sold out, but you can register for the wait list: http://www.microsoft.com/europe/TechEd/

    Read the article

  • PandoraBar Packs Pandora Radio Client into a Compact Case

    - by Jason Fitzpatrick
    This stylish and compact build makes it easy to enjoy streaming radio without the bulk and overhead of running your entire computer to do so. Check out the video to see the compact streaming radio box in action. Courtesy of tinker blog Engscope, we find this clean Pandora-client-in-box build. Currently the project blog has a cursory overview of the project with the demo video but promises future updates detailing the software and hardware components of the build. If you can’t wait that long, make sure to check out some of the previous Wi-Fi radio builds we’ve shared: DIY Wi-Fi Radio Brings Wireless Tunes Anywhere in Your House and Wi-Fi Speakers Stream Music Anywhere. Pandobar [via Hacked Gadgets] How To Create a Customized Windows 7 Installation Disc With Integrated Updates How to Get Pro Features in Windows Home Versions with Third Party Tools HTG Explains: Is ReadyBoost Worth Using?

    Read the article

  • My Message to the Software Craftsmanship Group

    - by Liam McLennan
    This is a message I posted to the software craftsmanship group, looking for a week-long, pairing / skill sharing opportunity in the USA. I am a journeyman software craftsman, currenlty living and working in Brisbane Australia. In April I am going to travel to the US to attend Alt.Net Seattle and Seattle codecamp. In between the two conferences I have five days in which I would like to undertake a craftsmanship mini-apprenticeship, pairing and skill sharing with your company. I do not require any compensation other than the opportunity to assist you and learn from you. Although my conferences are in Seattle I am happy to travel anywhere in the USA and Canada (excluding Hawaii :) ). Things I am good at: .NET web development, javascript, creating software that solves problems Things I am learning: Ruby, Rails, javascript If you are interested in having me as visiting craftsman from the 12th to the 16th of April please reply on this mailing list or contact me directly. Liam McLennan Now I wait…

    Read the article

  • Microsoft Office 2010 Downloads Available For MSDN Subscribers

    - by Gopinath
    Microsoft released the next version of it’s productivity suite, Office 2010, to yesterday to all it’s MSDN subscribers. If you have MSDN subscription, head over to MSDN downloads and grab the installer. Unlike the earlier release of Office suite that had various versions like standard, professional & ultimate, Office 2010 has only one version – Professional Plus. For those who don’t have MSDN subscription, you have to wait till June to buy the Office 2010 DVDs from stores. Join us on Facebook to read all our stories right inside your Facebook news feed.

    Read the article

  • Using the JRockit Flight Recorder as an Exception Profiler.

    - by Marcus Hirt
    There is a lot of new data points in the JRockit Flight Recorder compared to the data available in the old JRA. One set of data deals with exceptions and where they are thrown. In JRA, it was possible to tell how many exceptions were thrown, but it was not possible to determine from where they were thrown. Here is how to do a recording with exception profiling enabled from JRockit Mission Control. 1. Right click on the JVM to profile, select Start Flight Recording. 2. Select the Profiling with Exceptions template.   3. Wait for the recording to finish. The count down for the time left will show in the Flight Recorder Control view. 4. When done the recording will automatically be downloaded and displayed. To show the exceptions, go to the Code | Exceptions tab.

    Read the article

  • How do software updates work?

    - by Jonas
    I would like to know how software updates work for my Ubuntu Server 10.10. I have been recommended to use apt-get install for installing new software and apt-get update for updating software for a Ubuntu Server in production use. Because these packages are tested for Ubuntu in contrast to download source code and compile the software on the box. But on my Ubuntu Server 10.10, I don't get the latest stable version of PostgreSQL (9) or the latest stable version of Nginx (8) using apt-get install. So how is this working, will these software be updated when I later run apt-get update or do I have to later run apt-get install again, or do I have to wait for the next release of Ubuntu to get them? And are patches and security updates managed in the same way? Or can they be updated automatically? If there is such a setting, how do I check what my system is using?

    Read the article

  • Star Sightings at MIX 10

    Hey its Vegas baby! Brad was stylin. Tim and I were a poor mans Vin Diesel and Tom Cruise. The jacket and shades actually suited Karen. Dan looked like he worked in Vegas. Ward was, well, Ward. Was it the town, the conference, or are we all just wacky developer/designer types? Ward Bell brought along his jacket, shirt and shades and of course we all just had to get into the act. (If you think this is crazy, wait til you see what Ward did to top it in our upcoming Silverlight TV video!) Yet another...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

    Read the article

  • Converting projects to use Automatic NuGet restore

    - by terje
    Originally posted on: http://geekswithblogs.net/terje/archive/2014/06/11/converting-projects-to-use-automatic-nuget-restore.aspxDownload tool In version 2.7 of NuGet automatic nuget restore was introduced, meaning you no longer need to distort your msbuild project files with nuget target information.   Visual Studio and TFS 2013 build have this enabled by default.  However, if your project was created before this was introduced, and/or if you have used the “Enable NuGet Package Restore” afterwards, you now have a series of unwanted things in your projects, and a series of project files that have been modified – and – you no longer neither want nor need this !  You might also get into some unwanted issues due to these modifications.  This is a MSBuild modification that was needed only before NuGet 2.7 ! So: DON’T USE THIS FUNCTION !!! There is an issue https://nuget.codeplex.com/workitem/4019 on this on the NuGet project site to get this function removed, renamed or at least moved farther away from the top level (please help vote it up!).  The response seems to be that it WILL BE removed, around version 3.0. This function does nothing you need after the introduction of NuGet 2.7.  What is also unfortunate is the naming of it – it implies that it is needed, it is not, and what is worse, there is no corresponding function to remove what it does ! So to fix this use the tool named IFix, that will fix this issue for you   - all free of course, and the code is open source.  Also report issues there:  https://github.com/OsirisTerje/IFix    IFix information DOWNLOAD HERE This command line tool installs using an MSI, and add itself to the system path.  If you work in a team, you will probably need to use the  tool multiple times.  Anyone in the team may at any time use the “Enable NuGet Package Restore” function and mess up your project again.  The IFix program can be run either in a  check modus, where it does not write anything back – it only checks if you have any issues, or in a Fix mode, where it will also perform the necessary fixes for you. The IFix program is used like this: IFix <command> [-c/--check] [-f/--fix]  [-v/--verbose] The command in this case is “nugetrestore”.  It will do a check from the location where it is being called, and run through all subfolders from that location. So  “IFix nugetrestore  --check” , will do the check ,  and “IFix nugetrestore  --fix”  will perform the changes, for all files and folders below the current working directory. (Note that --check  can be replaced with only –c, and --fix with –f, and so on. ) BEWARE: When you run the fix option, all solutions to be affected must be closed in Visual Studio ! So, if you just want to DO it, then: IFix nugetrestore --check to see if you have issues then IFix nugetrestore  --fix to fix them. How does it work IFix nugetrestore  checks and optionally fixes four issues that the older enabling of nuget restore did.  The issues are related to the MSBuild projess, and are: Deleting the nuget.targets file. Deleting the nuget.exe that is located under the .nuget folder Removing all references to nuget.targets in the solution file Removing all properties and target imports of nuget.targets inside the csproj files. IFix fixes these issues in the same sequence. The first step, removing the nuget.targets file is the most critical one, and all instances of the nuget.targets file within the scope of a solution has to be removed, and in addition it has to be done with the solution closed in Visual Studio.  If Visual Studio finds a nuget.targets file, the csproj files will be automatically messed up again. This means the removal process above might need to be done multiple times, specially when you’re working with a team, and that solution context menu still has the “Enable NuGet Package Restore” function.  Someone on the team might inadvertently do this at any time. It can be a good idea to add this check to a checkin policy – if you run TFS standard version control, but that will have no effect if you use TFS Git version control of course. So, better be prepared to run the IFix check from time to time. Or, even better, install IFix on your build servers, and add a call to IFix nugetrestore --check in the TFS Build script.    How does it look As a first example I have run the IFix program from the top of a set of git repositories, so it spans multiple repositories with multiple solutions. The result from the check option is as follows: We see the four red lines, there is one for each of the four checks we talked about in the previous section. The fact that they are red, means we have that particular issue. The first section (above the first red text line) is the nuget targets section.  Notice  No.1, it says it has found no paths to copy.  What IFix does here is to check if there are any defined paths to other nuget galleries.  If there are, then those are copied over to the nuget.config file, where is where it should be in version 2.7 and above.   No.2 says it has found the particular nuget.targets file,  No.3  states it HAS found some other nuget galleries defines in the targets file, which then it would like to copy to the config.file. No.4 is the section for nuget.exe files, and list those it has found, and which it would like to delete. No 5 states it has found a reference to nuget.targets in the solution file.  This reference comes from the fact that the .nuget folder is a solution folder, and the items within are described in the solution file. It then checks the csproj files, and as can be seen from the last red line, it ha found issues in 96 out of 198 csproj files.  There are two possible issues in a csproj files.  No.6 is the first one, and the most common and most important one, an “Import project” section.  This is the section that calls the nuget.targets files.  No.7 is another issue, which seems to sometimes be there, sometimes not, it is a RestorePackages property, which also should go away. Now, if we run the IFix nugetrestore –fix command, and then the check again after that, the result is: All green !

    Read the article

  • How do software updates work on Ubuntu?

    - by Jonas
    I would like to know how software updates work for my Ubuntu Server 10.10. I have been recommended to use apt-get install for installing new software and apt-get update for updating software for a Ubuntu Server in production use. Because these packages are tested for Ubuntu in contrast to download source code and compile the software on the box. But on my Ubuntu Server 10.10, I don't get the latest stable version of PostgreSQL (9) or the latest stable version of Nginx (8) using apt-get install. So how is this working, will these software be updated when I later run apt-get update or do I have to later run apt-get install again, or do I have to wait for the next release of Ubuntu to get them? And are patches and security updates managed in the same way? Or can they be updated automatically? If there is such a setting, how do I check what my system is using?

    Read the article

  • Lubuntu 12.04 PPC slow startup and shutdown

    - by Carlo Bertuccini
    I've installed Lubuntu 12.04 on a Powerbook G4 (PowerPC 1GHz, 1 gb ram, Geforce MX 440). Everything works perfectly except the startup and shutdown. To startup my system I have to wait about 3 minutes (and similar time to shutdown) Giving a look @ /var/log/dmesg I noticed the following [drm] nouveau 0000:00:10.0: Detected an NV10 generation card (0x017900a5) checking generic (b8004000 151800) vs hw (b8000000 80000000) fb: conflicting fb hw usage nouveaufb vs 0Ffb NVDA,Displ - removing generic driver The only issue concerns Nouveau ... inside my /var/log/kern.log says what follows BUG: soft lockup - CPU#0 stuck for 22s! I've booted passing the "nouveau.modeset=0" parameter and the system boot in 15 seconds but with 4 bit graphics -- Any idea how to fix? Thanks in advance for any help

    Read the article

  • Check If You Are Eligible To Try Amazon Fire TV Free for 30 days

    - by Gopinath
    Re/Code first broke the story of Amazon offering its customers to try Amazon Fire TV free for 30 days. The Amazon Fire TV costs $99 but with this offer you get a chance to try it for 30 days without paying any money. After 30 days if you are interested you can keep it with you by paying $99 otherwise you can return it to Amazon. All the costs associated with shipping to your home as well as returning back to Amazon are covered by the offer, which means it’s a real FREE offer to try! This offer is not available for everyone, but selected customers are receiving emails from Amazon. If you are interested to try free Amazon TV either you may wait to receive an offer email or click on this link to check if you are eligible. I verified it today and it says that I’m not eligible for this offer. Try your luck and all the best.

    Read the article

  • Turn-based Strategy Loop

    - by Djentleman
    I'm working on a strategy game. It's turn-based and card-based (think Dominion-style), done in a client, with eventual AI in the works. I've already implemented almost all of the game logic (methods for calculations and suchlike) and I'm starting to work on the actual game loop. What is the "best" way to implement a game loop in such a game? Should I use a simple "while gameActive" loop that keeps running until gameActive is False, with sections that wait for player input? Or should it be managed through the UI with player actions determining what happens and when? Any help is appreciated. I'm doing it in Python (for now at least) to get my Python skills up a bit, although the language shouldn't matter for this question.

    Read the article

  • Root filesystem check fails after power failure during installation

    - by Oo Nwoye
    During the "install" phase of the upgrade there was a power failure. After when starting up again the following errors are reported: init: udevtrigger main process (420) terminated with status 1 init: udevtrigger post-stop process (428) terminated with status 1 init: udevmonitor main process (419) killed by TERM signal The disk drive for / is not ready yet or not present Continue to wait; or press S to skip mounting or M for manual recovery Pressing M gives me the following message: Root filesystem check failed. A maintenance shell will now be started. CONTROL-D will terminate this shell and reboot the system.

    Read the article

  • frame lock networking

    - by kochol
    I'm developing an RTS game and I want to add multiplayer support to my game. I picked the easiest technique to implement for start frame locking technique. I used server client networking architecture (I think it's my first mistake I think using peer to peer is a better one for this) On game update every clients send their commands and maybe receive some command then render the frame and wait for all clients to send their update complete message then all of them can go for the next frame. I send commands and all logic is calculated on the clients based on commands but the clients can go out of sync easily. Every AI controlled units make different decisions on each clients What I have to do to sync my game? Do you suggest me a better network architecture or technique?

    Read the article

  • How do I break an image into 6 or 8 pieces of different shapes?

    - by Anil gupta
    I am working on puzzle game, where the player can select an image from iPhone photo gallery. The selected image will save in puzzle page and after 3 second wait the selected image will be broken into 6 or 8 parts of different shapes. Then player will arrange these broken parts of images to make the original image. I am not getting idea how to break the image and merged so that player arrange the broken part. I want to break image like this below frame. I am developing this game in cocos2d.

    Read the article

  • Another ubuntu one music problem with ID3-Tags ("unknown artist" problem)

    - by Andi
    I started using ubuntu one a few days ago. I put some MP3s into the cloud music folder and I can play them just fine in the music web and andriod applications. The problem is that all files are sorted under "unknown artist" and "unknown album" and the title is either the file name or a part of it (which is from the service "guessing the title" I guess). It seems the problem happened before. I looked in the FAQ, which said this happens with m4a files, but I use mp3 files. The ID3 tags are correct and are tagged with ID3v1 and ID3v2. I read to wait, until the service can catch up with the tagging, so I waited 24 hours, still nothing. Every single file is still listed under unknown artist/unknown album. I'm running out of options here :/

    Read the article

  • ddclient - wont update Invalid Keyword for 'ip' =

    - by stueng
    /etc/ddclient.conf use=web, web=checkip.dyndns.org/, web-skip='IP Address' protocol=easydns ssl=yes server=members.easydns.com login=stueng password='****' home.***.** /var/log/syslog Jun 4 13:02:34 XBMCuntu ddclient[10554]: WARNING: file /var/cache/ddclient/ddclient.cache, line 3: Invalid Value for keyword 'ip' = '' Jun 4 13:02:34 XBMCuntu ddclient[10554]: WARNING: skipping update of home.***.** from <nothing> to 90.193.*.*. Jun 4 13:02:34 XBMCuntu ddclient[10554]: WARNING: last updated <never> but last attempt on Mon Jun 4 13:01:57 2012 failed. Jun 4 13:02:34 XBMCuntu ddclient[10554]: WARNING: Wait at least 5 minutes between update attempts. Help?

    Read the article

  • SQLCMD Mode: give it one more chance

    - by Maria Zakourdaev
      - Click on me. Choose me. - asked one forgotten feature when some bored DBA was purposelessly wondering through the Management Studio menu at the end of her long and busy working day. - Why would I use you? I have heard of no one who does. What are you for? - perplexedly wondered aged and wise DBA. At least that DBA thought she was aged and wise though each day tried to prove to her that she wasn't. - I know you. You are quite lazy. Why would you do additional clicks to move from window to window? From Tool to tool ? This is irritating, isn't it? I can run windows system commands, sql statements and much more from the same script, from the same query window! - I have all my tools that I‘m used to, I have Management Studio, Cmd, Powershell. They can do anything for me. I don’t need additional tools. - I promise you, you will like me. – the thing continued to whine . - All right, show me. – she gave up. It’s always this way, she thought sadly, - easier to agree than to explain why you don’t want. - Enable me and then think about anything that you always couldn’t do through the management studio and had to use other tools. - Ok. Google for me the list of greatest features of SQL SERVER 2012. - Well... I’m not sure... Think about something else. - Ok, here is something easy for you. I want to check if file folder exists or if file is there. Though, I can easily do this using xp_cmdshell … - This is easy for me. – rejoiced the feature. By the way, having the items of the menu talking to you usually means you should stop working and go home. Or drink coffee. Or both. Well, aged and wise dba wasn’t thinking about the weirdness of the situation at that moment. - After enabling me, – said unfairly forgotten feature (it was thinking of itself in such manner) – after enabling me you can use all command line commands in the same management studio query window by adding two exclamation marks !! at the beginning of the script line to denote that you want to use cmd command: -Just keep in mind that when using this feature, you are actually running the commands ON YOUR computer and not on SQL server that query window is connected to. This is main difference from using xp_cmdshell which is executing commands on sql server itself. Bottomline, use UNC path instead of local path. - Look, there are much more than that. - The SQLCMD feature was getting exited.- You can get IP of your servers, create, rename and drop folders. You can see the contents of any file anywhere and even start different tools from the same query window: Not so aged and wise DBA was getting interested: - I also want to run different scripts on different servers without changing connection of the query window. - Sure, sure! Another great feature that CMDmode is providing us with and giving more power to querying. Use “:” to use additional features, like :connect that allows you to change connection: - Now imagine, you have one script where you have all your changes, like creating staging table on the DWH staging server, adding fact table to DWH itself and updating stored procedures in the server where reporting database is located. - Now, give me more challenges! - Script out a list of stored procedures into the text files. - You can do it easily by using command :out which will write the query results into the specified text file. The output can be the code of the stored procedure or any data. Actually this is the same as changing the query output into the file instead of the grid. - Now, take all of the scripts and run all of them, one by one, on the different server.  - Easily - Come on... I’m sure that you can not... -Why not? Naturally, I can do it using :r commant which is opening a script and executing it. Look, I can also use :setvar command to define an environment variable in SQLCMD mode. Just note that you have to leave the empty string between :r commands, otherwise it’s not working although I have no idea why. - Wow.- She was really impressed. - Ok, I’ll go to try all those… -Wait, wait! I know how to google the SQL SERVER features for you! This example will open chrome explorer with search results for the “SQL server 2012 top features” ( change the path to suit your PC): “Well, this can be probably useful stuff, maybe this feature is really unfairly forgotten”, thought the DBA while going through the dark empty parking lot to her lonely car. “As someone really wise once said: “It is what we think we know that keeps us from learning. Learn, unlearn and relearn”.

    Read the article

  • combining ruby and C++

    - by Shingetsu
    Hello /* programmers */ (I usually hang in SO) I've been discussing a conceptual project with a friend of mine and the the most effective way we've seen of doing it is writing the engine in C++ while the logic would be done in Ruby. However, we would need data to be passed around often, for example: Engine reports that A happened, that gets triggered in a proc array (event "A" is passed but proc doesnt use it) Ruby decides that we need to wait for B to happen Ruby adds a proc to an array. The array of procs is iterated during each cycle in the C++ engine C++ engine reports that B happened and passes "event B (should be a ruby object) Ruby receives event B and decides what to do next I don't work with multiple languages often, and was wondering if it's possible to implement things in this way. I know that there's the ruby VALUE in C++, but would like to know the standard way of combining the two. (of course I know ruby follows the perl "more than 1 way to do it", but there's often a standardized way)

    Read the article

  • Licensing Options for a dead project

    - by Russell Durham
    I'm currently working on a project where the original author informally told me that he didn't want to publish the source. Since then, the original author has gone leaving me to be the sole developer on the project. I've tried to contact him several times about making the project open source so that I can have other developers assist me but he is not responding to any communications. I'm not planning on trying to make money of the software, I just want a general license that allows me to put the code on GitHub or BitBucket so that other people in the community can assist me with the development. Can I do this since he is gone and not responding to any form of communication? Is there a time period I need to wait? I know what I asking for is legal advice, I just have no idea where to start looking to find the answer so I decided to start here.

    Read the article

  • Modify actions when battery is critically low?

    - by Bjarke Freund-Hansen
    I am running ubuntu (not xubuntu!) and am using xfce4 on my laptop. When my laptop battery is critically low, ubuntu/xfce4 performs some action (perhaps hibernate?) which causes my laptop to shut down. However when I start it again, it never comes up. I don't even get BIOS or anything on the screen, it is completely black. The only way to get it back up is to take it apart, remove the internal cmos battery as well as the main battery, wait a few minutes, and put it back together. Obeviously this is not optimal. How do I disable all actions when the battery is critically low? I would rather have it run out of power, than ending up in this error condition. Thanks in advance. :)

    Read the article

  • C# async and actors

    - by Alex.Davies
    If you read my last post about async, you might be wondering what drove me to write such odd code in the first place. The short answer is that .NET Demon is written using NAct Actors. Actors are an old idea, which I believe deserve a renaissance under C# 5. The idea is to isolate each stateful object so that only one thread has access to its state at any point in time. That much should be familiar, it's equivalent to traditional lock-based synchronization. The different part is that actors pass "messages" to each other rather than calling a method and waiting for it to return. By doing that, each thread can only ever be holding one lock. This completely eliminates deadlocks, my least favourite concurrency problem. Most people who use actors take this quite literally, and there are plenty of frameworks which help you to create message classes and loops which can receive the messages, inspect what type of message they are, and process them accordingly. But I write C# for a reason. Do I really have to choose between using actors and everything I love about object orientation in C#? Type safety Interfaces Inheritance Generics As it turns out, no. You don't need to choose between messages and method calls. A method call makes a perfectly good message, as long as you don't wait for it to return. This is where asynchonous methods come in. I have used NAct for a while to wrap my objects in a proxy layer. As long as I followed the rule that methods must always return void, NAct queued up the call for later, and immediately released my thread. When I needed to get information out of other actors, I could use EventHandlers and callbacks (continuation passing style, for any CS geeks reading), and NAct would call me back in my isolated thread without blocking the actor that raised the event. Using callbacks looks horrible though. To remind you: m_BuildControl.FilterEnabledForBuilding(    projects,    enabledProjects = m_OutOfDateProjectFinder.FilterNeedsBuilding(        enabledProjects,             newDirtyProjects =             {                 ....... Which is why I'm really happy that NAct now supports async methods. Now, methods are allowed to return Task rather than just void. I can await those methods, and C# 5 will turn the rest of my method into a continuation for me. NAct will run the other method in the other actor's context, but will make sure that when my method resumes, we're back in my context. Neither actor was ever blocked waiting for the other one. Apart from when they were actually busy doing something, they were responsive to concurrent messages from other sources. To be fair, you could use async methods with lock statements to achieve exactly the same thing, but it's ugly. Here's a realistic example of an object that has a queue of data that gets passed to another object to be processed: class QueueProcessor {    private readonly ItemProcessor m_ItemProcessor = ...     private readonly object m_Sync = new object();    private Queue<object> m_DataQueue = ...    private List<object> m_Results = ...     public async Task ProcessOne() {         object data = null;         lock (m_Sync)         {             data = m_DataQueue.Dequeue();         }         var processedData = await m_ItemProcessor.ProcessData(data); lock (m_Sync)         {             m_Results.Add(processedData);         }     } } We needed to write two lock blocks, one to get the data to process, one to store the result. The worrying part is how easily we could have forgotten one of the locks. Compare that to the version using NAct: class QueueProcessorActor : IActor { private readonly ItemProcessor m_ItemProcessor = ... private Queue<object> m_DataQueue = ... private List<object> m_Results = ... public async Task ProcessOne()     {         // We are an actor, it's always thread-safe to access our private fields         var data = m_DataQueue.Dequeue();         var processedData = await m_ItemProcessor.ProcessData(data);         m_Results.Add(processedData);     } } You don't have to explicitly lock anywhere, NAct ensures that your code will only ever run on one thread, because it's an actor. Either way, async is definitely better than traditional synchronous code. Here's a diagram of what a typical synchronous implementation might do: The left side shows what is running on the thread that has the lock required to access the QueueProcessor's data. The red section is where that lock is held, but doesn't need to be. Contrast that with the async version we wrote above: Here, the lock is released in the middle. The QueueProcessor is free to do something else. Most importantly, even if the ItemProcessor sometimes calls the QueueProcessor, they can never deadlock waiting for each other. So I thoroughly recommend you use async for all code that has to wait a while for things. And if you find yourself writing lots of lock statements, think about using actors as well. Using actors and async together really takes the misery out of concurrent programming.

    Read the article

< Previous Page | 76 77 78 79 80 81 82 83 84 85 86 87  | Next Page >