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  • Finding the problem on a partially succeeded build

    - by Martin Hinshelwood
    Now that I have the Build failing because of a genuine bug and not just because of a test framework failure, lets see if we can trace through to finding why the first test in our new application failed. Lets look at the build and see if we can see why there is a red cross on it. First, lets open that build list. On Team Explorer Expand your Team Project Collection | Team Project and then Builds. Double click the offending build. Figure: Opening the Build list is a key way to see what the current state of your software is.   Figure: A test is failing, but we can now view the Test Results to find the problem      Figure: You can quite clearly see that the test has failed with “The device is not ready”. To me the “The Device is not ready” smacks of a System.IO exception, but it passed on my local computer, so why not on the build server? Its a FaultException so it is most likely coming from the Service and not the client, so lets take a look at the client method that the test is calling: bool IProfileService.SaveDefaultProjectFile(string strComputerName) { ProjectFile file = new ProjectFile() { ProjectFileName = strComputerName + "_" + System.DateTime.Now.ToString("yyyyMMddhhmmsss") + ".xml", ConnectionString = "persist security info=False; pooling=False; data source=(local); application name=SSW.SQLDeploy.vshost.exe; integrated security=SSPI; initial catalog=SSWSQLDeployNorthwindSample", DateCreated = System.DateTime.Now, DateUpdated = System.DateTime.Now, FolderPath = @"C:\Program Files\SSW SQL Deploy\SampleData\", IsComplete=false, Version = "1.3", NewDatabase = true, TimeOut = 5, TurnOnMSDE = false, Mode="AutomaticMode" }; string strFolderPath = "D:\\"; //LocalSettings.ProjectFileBasePath; string strFileName = strFolderPath + file.ProjectFileName; try { using (FileStream fs = new FileStream(strFileName, FileMode.Create)) { DataContractSerializer serializer = new DataContractSerializer(typeof(ProjectFile)); using (XmlDictionaryWriter writer = XmlDictionaryWriter.CreateTextWriter(fs)) { serializer.WriteObject(writer, file); } } } catch (Exception ex) { //TODO: Log the exception throw ex; return false; } return true; } Figure: You can see on lines 9 and 18 that there are calls being made to specific folders and disks. What is wrong with this code? What assumptions mistakes could the developer have made to make this look OK: That every install would be to “C:\Program Files\SSW SQL Deploy” That every computer would have a “D:\\” That checking in code at 6pm because the had to go home was a good idea. lets solve each of these problems: We are in a web service… lets store data within the web root. So we can call “Server.MapPath(“~/App_Data/SSW SQL Deploy\SampleData”) instead. Never reference an explicit path. If you need some storage for your application use IsolatedStorage. Shelve your code instead. What else could have been done? Code review before check-in – The developer should have shelved their code and asked another dev to look at it. Use Defensive programming – Make sure that any code that has the possibility of failing has checks. Any more options? Let me know and I will add them. What do we do? The correct things to do is to add a Bug to the backlog, but as this is probably going to be fixed in sprint, I will add it directly to the sprint backlog. Right click on the failing test Select “Create Work Item | Bug” Figure: Create an associated bug to add to the backlog. Set the values for the Bug making sure that it goes into the right sprint and Area. Make your steps to reproduce as explicit as possible, but “See test” is valid under these circumstances.   Figure: Add it to the correct Area and set the Iteration to the Area name or the Sprint if you think it will be fixed in Sprint and make sure you bring it up at the next Scrum Meeting. Note: make sure you leave the “Assigned To” field blank as in Scrum team members sign up for work, you do not give it to them. The developer who broke the test will most likely either sign up for the bug, or say that they are stuck and need help. Note: Visual Studio has taken care of associating the failing test with the Bug. Save… Technorati Tags: WCF,MSTest,MSBuild,Team Build 2010,Team Test 2010,Team Build,Team Test

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  • What is the best database design and/or software to model a thesaurus?

    - by Miles O'Keefe
    I would like to design a web app that functions as a simple thesaurus : a long list of words with attributes, all of which are linked to each other. Wikipedia defines it as: In Information Science, Library Science, and Information Technology, specialized thesauri are designed for information retrieval. They are a type of controlled vocabulary, for indexing or tagging purposes. Such a thesaurus can be used as the basis of an index for online material. The Art and Architecture Thesaurus, for example, is used to index the Canadian Information retrieval thesauri are formally organized so that existing relationships between concepts are made explicit. What database software, design or model would best fit this? Are PHP and MySQL good technologies to handle it?

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  • Look for Oracle at the 2010 ISM San Diego Conference

    - by [email protected]
    Oracle is sponsoring and exhibiting at ISM's 95th Annual International Supply Management Conference and Educational Exhibit on April 25th through 28th.   Be sure to catch our presentation with Hackett that explores how procurement can use payables to boost an organization's balance and income statements. Pierre Mitchell from Hackett will be sharing groundbreaking new research that identifies explicit links between a strategic approach to supplier payments and world-class performance.   If your organization can benefit from increased margin, improved working capital, greater efficiency, and reduced risk, then you can't afford to miss this session. We'll be presenting on Monday at 5:00pm in Exhibit  Hall D.       Some of Oracle's top talent will be available to answer your questions in booth number 527. It is a great opportunity to learn about Oracle's innovations for supplier management, spend classification, invoice automation, and On Demand delivery of procurement applications.  

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  • C# 4.0: COM Interop Improvements

    - by Paulo Morgado
    Dynamic resolution as well as named and optional arguments greatly improve the experience of interoperating with COM APIs such as Office Automation Primary Interop Assemblies (PIAs). But, in order to alleviate even more COM Interop development, a few COM-specific features were also added to C# 4.0. Ommiting ref Because of a different programming model, many COM APIs contain a lot of reference parameters. These parameters are typically not meant to mutate a passed-in argument, but are simply another way of passing value parameters. Specifically for COM methods, the compiler allows to declare the method call passing the arguments by value and will automatically generate the necessary temporary variables to hold the values in order to pass them by reference and will discard their values after the call returns. From the point of view of the programmer, the arguments are being passed by value. This method call: object fileName = "Test.docx"; object missing = Missing.Value; document.SaveAs(ref fileName, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing); can now be written like this: document.SaveAs("Test.docx", Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value); And because all parameters that are receiving the Missing.Value value have that value as its default value, the declaration of the method call can even be reduced to this: document.SaveAs("Test.docx"); Dynamic Import Many COM methods accept and return variant types, which are represented in the PIAs as object. In the vast majority of cases, a programmer calling these methods already knows the static type of a returned object form the context of the call, but has to explicitly perform a cast on the returned values to make use of that knowledge. These casts are so common that they constitute a major nuisance. To make the developer’s life easier, it is now possible to import the COM APIs in such a way that variants are instead represented using the type dynamic which means that COM signatures have now occurrences of dynamic instead of object. This means that members of a returned object can now be easily accessed or assigned into a strongly typed variable without having to cast. Instead of this code: ((Excel.Range)(excel.Cells[1, 1])).Value2 = "Hello World!"; this code can now be used: excel.Cells[1, 1] = "Hello World!"; And instead of this: Excel.Range range = (Excel.Range)(excel.Cells[1, 1]); this can be used: Excel.Range range = excel.Cells[1, 1]; Indexed And Default Properties A few COM interface features are still not available in C#. On the top of the list are indexed properties and default properties. As mentioned above, these will be possible if the COM interface is accessed dynamically, but will not be recognized by statically typed C# code. No PIAs – Type Equivalence And Type Embedding For assemblies indentified with PrimaryInteropAssemblyAttribute, the compiler will create equivalent types (interfaces, structs, enumerations and delegates) and embed them in the generated assembly. To reduce the final size of the generated assembly, only the used types and their used members will be generated and embedded. Although this makes development and deployment of applications using the COM components easier because there’s no need to deploy the PIAs, COM component developers are still required to build the PIAs.

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  • Monitoring the Application alongside SQL Server

    - by Tony Davis
    Sometimes, on Simple-Talk, it takes a while to spot strange and unexpected patterns of user activity, or small bugs. For example, one morning we spotted that an article’s comment count had leapt to 1485, but that only four were displayed. With some rooting around in Google Analytics, and the endlessly annoying Community Server admin-interface, we were able to work out that a few days previously the article had been subject to a spam attack and that the comment count was for some reason including both accepted and unaccepted comments (which in turn uncovered a bug in the SQL). This sort of incident made us a lot keener on monitoring Simple-talk website usage more effectively. However, the metrics we wanted are troublesome, because they are far too specific for Google Analytics to measure, and the SQL Server backend doesn’t keep sufficient information to enable us to plot trends. The latter could provide, for example, the total number of comments made on, or votes cast for, articles, over all time, but not the number that occur by hour over a set time. We lacked a baseline, in other words. We couldn’t alter the database, as it is a bought-in package. We had neither the resources nor inclination to build-in dedicated application monitoring. Possibly, we could investigate a third-party tool to do the job; but then it occurred to us that we were already using a monitoring tool (SQL Monitor) to keep an eye on the database. It stored data, made graphs and sent alerts. Could we get it to monitor some aspects of the application as well? Of course, SQL Monitor’s single purpose is to check and monitor SQL Server, over time, rather than to monitor applications that use SQL Server. However, how different is the business of gathering and plotting SQL Server Wait Stats, from gathering and plotting various aspects of user activity on the site? Not a lot, it turns out. The latest version allows us to write our own custom monitoring scripts, meaning that we could now monitor any metric in the application that returns an integer. It took little time to write a simple SQL Query that collects basic metrics of the total number of subscribers, votes cast, comments made, or views of articles, over time. The SQL Monitor database polls Simple-Talk every second or so in order to get the latest totals, and can then store and plot this information, or even correlate SQL Server usage to application usage. You can see the live data by visiting monitor.red-gate.com. Click the "Analysis" tab, and select one of the "Simple-talk:" entries in the "Show" box and an appropriate data range (e.g. last 30 days). It’s nascent, and we’re still working on it, but it’s already given us more confidence that we’ll spot quickly trends, bugs, or bursts of ‘abnormal’ activity. If there is a sudden rise in comments, we get an alert, and if it’s due to a spam attack, we can moderate or ban the perpetrator very quickly. We’ve often argued that a tool should perform a single job well rather than turn into a Swiss-army knife, but ironically we’ve rather appreciated being able to make best use of what’s there anyway for a slightly different purpose. Is this a good or common practice? What do you think? Cheers, Tony.

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  • concurrency::accelerator_view

    - by Daniel Moth
    Overview We saw previously that accelerator represents a target for our C++ AMP computation or memory allocation and that there is a notion of a default accelerator. We ended that post by introducing how one can obtain accelerator_view objects from an accelerator object through the accelerator class's default_view property and the create_view method. The accelerator_view objects can be thought of as handles to an accelerator. You can also construct an accelerator_view given another accelerator_view (through the copy constructor or the assignment operator overload). Speaking of operator overloading, you can also compare (for equality and inequality) two accelerator_view objects between them to determine if they refer to the same underlying accelerator. We'll see later that when we use concurrency::array objects, the allocation of data takes place on an accelerator at array construction time, so there is a constructor overload that accepts an accelerator_view object. We'll also see later that a new concurrency::parallel_for_each function overload can take an accelerator_view object, so it knows on what target to execute the computation (represented by a lambda that the parallel_for_each also accepts). Beyond normal usage, accelerator_view is a quality of service concept that offers isolation to multiple "consumers" of an accelerator. If in your code you are accessing the accelerator from multiple threads (or, in general, from different parts of your app), then you'll want to create separate accelerator_view objects for each thread. flush, wait, and queuing_mode When you create an accelerator_view via the create_view method of the accelerator, you pass in an option of immediate or deferred, which are the two members of the queuing_mode enum. At any point you can access this value from the queuing_mode property of the accelerator_view. When the queuing_mode value is immediate (which is the default), any commands sent to the device such as kernel invocations and data transfers (e.g. parallel_for_each and copy, as we'll see in future posts), will get submitted as soon as the runtime sees fit (that is the definition of immediate). When the value of queuing_mode is deferred, the commands will be batched up. To send all buffered commands to the device for execution, there is a non-blocking flush method that you can call. If you wish to block until all the commands have been sent, there is a wait method you can call. Deferring is a more advanced scenario aimed at performance gains when you are submitting many device commands and you want to avoid the tiny overhead of flushing/submitting each command separately. Querying information Just like accelerator, accelerator_view exposes the is_debug and version properties. In fact, you can always access the accelerator object from the accelerator property on the accelerator_view class to access the accelerator interface we looked at previously. Interop with D3D (aka DX) In a later post I'll show an example of an app that uses C++ AMP to compute data that is used in pixel shaders. In those scenarios, you can benefit by integrating C++ AMP into your graphics pipeline and one of the building blocks for that is being able to use the same device context from both the compute kernel and the other shaders. You can do that by going from accelerator_view to device context (and vice versa), through part of our interop API in amp.h: *get_device, create_accelerator_view. More on those in a later post. Comments about this post by Daniel Moth welcome at the original blog.

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  • Do Not Optimize Without Measuring

    - by Alois Kraus
    Recently I had to do some performance work which included reading a lot of code. It is fascinating with what ideas people come up to solve a problem. Especially when there is no problem. When you look at other peoples code you will not be able to tell if it is well performing or not by reading it. You need to execute it with some sort of tracing or even better under a profiler. The first rule of the performance club is not to think and then to optimize but to measure, think and then optimize. The second rule is to do this do this in a loop to prevent slipping in bad things for too long into your code base. If you skip for some reason the measure step and optimize directly it is like changing the wave function in quantum mechanics. This has no observable effect in our world since it does represent only a probability distribution of all possible values. In quantum mechanics you need to let the wave function collapse to a single value. A collapsed wave function has therefore not many but one distinct value. This is what we physicists call a measurement. If you optimize your application without measuring it you are just changing the probability distribution of your potential performance values. Which performance your application actually has is still unknown. You only know that it will be within a specific range with a certain probability. As usual there are unlikely values within your distribution like a startup time of 20 minutes which should only happen once in 100 000 years. 100 000 years are a very short time when the first customer tries your heavily distributed networking application to run over a slow WIFI network… What is the point of this? Every programmer/architect has a mental performance model in his head. A model has always a set of explicit preconditions and a lot more implicit assumptions baked into it. When the model is good it will help you to think of good designs but it can also be the source of problems. In real world systems not all assumptions of your performance model (implicit or explicit) hold true any longer. The only way to connect your performance model and the real world is to measure it. In the WIFI example the model did assume a low latency high bandwidth LAN connection. If this assumption becomes wrong the system did have a drastic change in startup time. Lets look at a example. Lets assume we want to cache some expensive UI resource like fonts objects. For this undertaking we do create a Cache class with the UI themes we want to support. Since Fonts are expensive objects we do create it on demand the first time the theme is requested. A simple example of a Theme cache might look like this: using System; using System.Collections.Generic; using System.Drawing; struct Theme { public Color Color; public Font Font; } static class ThemeCache { static Dictionary<string, Theme> _Cache = new Dictionary<string, Theme> { {"Default", new Theme { Color = Color.AliceBlue }}, {"Theme12", new Theme { Color = Color.Aqua }}, }; public static Theme Get(string theme) { Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } return cached; } } class Program { static void Main(string[] args) { Theme item = ThemeCache.Get("Theme12"); item = ThemeCache.Get("Theme12"); } } This cache does create font objects only once since on first retrieve of the Theme object the font is added to the Theme object. When we let the application run it should print “Creating new font” only once. Right? Wrong! The vigilant readers have spotted the issue already. The creator of this cache class wanted to get maximum performance. So he decided that the Theme object should be a value type (struct) to not put too much pressure on the garbage collector. The code Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } does work with a copy of the value stored in the dictionary. This means we do mutate a copy of the Theme object and return it to our caller. But the original Theme object in the dictionary will have always null for the Font field! The solution is to change the declaration of struct Theme to class Theme or to update the theme object in the dictionary. Our cache as it is currently is actually a non caching cache. The funny thing was that I found out with a profiler by looking at which objects where finalized. I found way too many font objects to be finalized. After a bit debugging I found the allocation source for Font objects was this cache. Since this cache was there for years it means that the cache was never needed since I found no perf issue due to the creation of font objects. the cache was never profiled if it did bring any performance gain. to make the cache beneficial it needs to be accessed much more often. That was the story of the non caching cache. Next time I will write something something about measuring.

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  • Silabs cp2102 driver problem

    - by Zxy
    I downloaded appropriate driver from its own site, unzipped it and then tried to install it. But: root@ghostrider:/home/zero/Downloads# tar xvf cp210x-3.1.0.tar.gz cp210x-3.1.0/ cp210x-3.1.0/COPYING cp210x-3.1.0/cp210x/ cp210x-3.1.0/cp210x-3.1.0.spec cp210x-3.1.0/cp210x/.rpmmacros cp210x-3.1.0/cp210x/configure cp210x-3.1.0/cp210x/cp210x.c cp210x-3.1.0/cp210x/cp210x.h cp210x-3.1.0/cp210x/cp210xuniversal.c cp210x-3.1.0/cp210x/cp210xuniversal.h cp210x-3.1.0/cp210x/installmod cp210x-3.1.0/cp210x/Makefile24 cp210x-3.1.0/cp210x/Makefile26 cp210x-3.1.0/cp210x/rpmmacros24 cp210x-3.1.0/cp210x/rpmmacros26 cp210x-3.1.0/cp210x/Rules.make cp210x-3.1.0/INSTALL cp210x-3.1.0/makerpm cp210x-3.1.0/PACKAGE-LIST cp210x-3.1.0/README cp210x-3.1.0/RELEASE-NOTES cp210x-3.1.0/REPORTING-BUGS cp210x-3.1.0/rpm/ cp210x-3.1.0/rpm/brp-java-repack-jars cp210x-3.1.0/rpm/brp-python-bytecompile cp210x-3.1.0/rpm/check-rpaths cp210x-3.1.0/rpm/check-rpaths-worker root@ghostrider:/home/zero/Downloads# cd cp210x-3.1.0 root@ghostrider:/home/zero/Downloads/cp210x-3.1.0# ls COPYING cp210x-3.1.0.spec makerpm README REPORTING-BUGS cp210x INSTALL PACKAGE-LIST RELEASE-NOTES rpm root@ghostrider:/home/zero/Downloads/cp210x-3.1.0# run ./makerpm No command 'run' found, did you mean: Command 'zrun' from package 'moreutils' (universe) Command 'runq' from package 'exim4-daemon-heavy' (main) Command 'runq' from package 'exim4-daemon-light' (main) Command 'runq' from package 'sendmail-bin' (universe) Command 'grun' from package 'grun' (universe) Command 'qrun' from package 'torque-client' (universe) Command 'qrun' from package 'torque-client-x11' (universe) Command 'lrun' from package 'lustre-utils' (universe) Command 'rn' from package 'trn' (multiverse) Command 'rn' from package 'trn4' (multiverse) Command 'rup' from package 'rstat-client' (universe) Command 'srun' from package 'slurm-llnl' (universe) run: command not found root@ghostrider:/home/zero/Downloads/cp210x-3.1.0# sudo ./makerpm + uname -r + kernel_release=3.2.0-25-generic-pae + pwd + current_dir=/home/zero/Downloads/cp210x-3.1.0 + export current_dir + uname -r + KVER=3.2.0-25-generic-pae + echo 3.2.0-25-generic-pae + awk -F . -- { print $1 } + KVER1=3 + echo 3.2.0-25-generic-pae + awk -F . -- { print $2 } + KVER2=2 + sed -e s/3\.2\.//g + echo 3.2.0-25-generic-pae + KVER3=0-25-generic-pae + [ -f /root/.rpmmacros ] + echo 2 2 + [ 2 == 4 ] ./makerpm: 25: [: 2: unexpected operator + echo 0-25-generic-pae 0-25-generic-pae + [ 0-25-generic-pae -gt 15 ] ./makerpm: 29: [: Illegal number: 0-25-generic-pae + cp /home/zero/Downloads/cp210x-3.1.0/cp210x/rpmmacros24 /root/.rpmmacros + d=/var/tmp/silabs + [ ! -d /var/tmp/silabs ] + mkdir /var/tmp/silabs + cd /var/tmp/silabs + r=/var/tmp/silabs/rpmbuild + o=cp210x-3.1.0 + s=/var/tmp/silabs/rpmbuild/SOURCES + spec=cp210x-3.1.0.spec + rm -rf /var/tmp/silabs/rpmbuild + mkdir rpmbuild + mkdir rpmbuild/SOURCES + mkdir rpmbuild/SRPMS + mkdir rpmbuild/SPECS + mkdir rpmbuild/BUILD + mkdir rpmbuild/RPMS + cd /var/tmp/silabs/rpmbuild/SOURCES + rm -rf cp210x-3.1.0 + mkdir cp210x-3.1.0 + cp -r /home/zero/Downloads/cp210x-3.1.0/cp210x/Makefile24 /home/zero/Downloads/cp210x-3.1.0/cp210x/Makefile26 /home/zero/Downloads/cp210x- 3.1.0/cp210x/Rules.make /home/zero/Downloads/cp210x-3.1.0/cp210x/configure /home/zero/Downloads/cp210x-3.1.0/cp210x/cp210x.c /home/zero/Downloads/cp210x- 3.1.0/cp210x/cp210x.h /home/zero/Downloads/cp210x-3.1.0/cp210x/cp210xuniversal.c /home/zero/Downloads/cp210x-3.1.0/cp210x/cp210xuniversal.h /home/zero/Downloads/cp210x- 3.1.0/cp210x/installmod /home/zero/Downloads/cp210x-3.1.0/cp210x/rpmmacros24 /home/zero/Downloads/cp210x-3.1.0/cp210x/rpmmacros26 cp210x-3.1.0 + echo 2 2 + [ 2 == 4 ] ./makerpm: 64: [: 2: unexpected operator + echo 0-25-generic-pae 0-25-generic-pae + [ 0-25-generic-pae -gt 15 ] ./makerpm: 68: [: Illegal number: 0-25-generic-pae + cp /home/zero/Downloads/cp210x-3.1.0/cp210x/.rpmmacros24 cp210x-3.1.0/.rpmmacros cp: cannot stat `/home/zero/Downloads/cp210x-3.1.0/cp210x/.rpmmacros24': No such file or directory + MyCopy=0 + rm -f cp210x-3.1.0.tar + rm -f cp210x-3.1.0.tar.gz + tar -cf cp210x-3.1.0.tar cp210x-3.1.0 + gzip cp210x-3.1.0.tar + cp /home/zero/Downloads/cp210x-3.1.0/cp210x-3.1.0.spec /var/tmp/silabs/rpmbuild/SPECS + rpmbuild -ba /var/tmp/silabs/rpmbuild/SPECS/cp210x-3.1.0.spec ./makerpm: 121: ./makerpm: rpmbuild: not found + [ -f /root/.rpmmacros.cp210x ] How may I solve my problem? Thanks

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  • Save Points

    - by raghu.yadav
    Explicit save point : Requires an end user action before a bounded or unbounded task flow creates a save point. For example, an end user clicks a button that invokes a method call activity that, in turn, creates a save point Implicit save point : can only originate from a bounded task flow if 1) A session times out due to end user inactivity 2) An end user logs out without saving the data 3) An end user closes the only browser window, thus logging out of the application 4) An end user navigates away from the current application using control flow rules (for example, uses a goLink component to go to an external URL) and having unsaved data. good usecases and examples given by frank/biemond and on implicit save points http://www.oracle.com/technology/products/jdev/tips/fnimphius/cancelForm/cancelForm_wsp.html?_template=/ocom/print http://biemond.blogspot.com/2008/04/automatically-save-transactions-with.html

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  • Why you need to tag your build servers in TFS

    - by Martin Hinshelwood
    At SSW we use gated check-in for all of our projects. The benefits are based on the number of developers you have working on your project. Lets say you have 30 developers and each developer breaks the build once per month. That could mean that you have a broken build every day! Gated check-ins help, but they have a down side that manifests as queued builds and moaning developers. The way to combat this is to have more build servers, but with that comes complexity. Inevitably you will need to install components that you would expect to be installed on target computers, but how do you keep track of which build servers have which bits? What about a geographically diverse team? If you have a centrally controlled infrastructure you might have build servers in multiple regions and you don’t want teams in Sydney copying files from Beijing and vice a versa on a regular basis. So, what is the answer. Its Tags. You can add a set of Tags to your agents and then set which tags to look for in the build definition. Figure: Open up your Build Controller Manager Select “Build | Manage Build Controllers…” to get a list of all of your controllers and he build agents that are associated with them. Figure: the list of build agents and their controllers Each of these Agents might be subtly different. For example only one of these agents has FTP software installed. This software is required for only one of the many builds we have set up. My ethos for build servers is to keep them as clean as possible and not to install anything that is not absolutely necessary. For me that means anything that does not add a *.target file is suspect, and should really be under version control and called via the command line from there. So, some of the things you may install are: Silverlight 4 SDK Visual Studio 2010 Visual Studio 2008 WIX etc You should not install things that will not end up on the target users computer. For a website that means something different to a client than to a server, but I am sure you get the idea. One thing you can do to make things easier is to create a tag for each of the things that you install. that way developers can find the things they need. We may change to using a more generic tagging structure (Like “Web Application” or “WinForms Application”) if this gets too unwieldy, but for now the list of tags is limited. Figure: Tags associated with one of our build agents Once you have your Build Agents all tagged up ALL your builds will start to fail This is because the default setting for a build is to look for an Agent that exactly matches the tags for the build, and we have not added any yet. The quick way to fix this is to change the “Tag Comparison Operator” from “ExactMatch” to “MatchAtLease” to get your build immediately working. Figure: Tag Comparison Operator changes to MatchAtLeast to get builds to run. The next thing to do is look for specific tags. You just select from the list of available tags and the controller will make sure you get to a build agent that uses them. Figure: I want Silverlight, VS2010 and WIX, but do not care about Location. And there you go, you can now have build agents for different purposes and regions within the same environment. You can also use name filtering, so if you have a good Agent naming convention you can filter by that for regions. For example, your Agents might be “SYDVMAPTFSBP01” and “SYDVMAPTFSBP02” so a name filter of “SYD*” would target all of the Sydney build agents. Figure: Agent names can be used for filtering as well This flexibility will allow you to build better software by reducing the likelihood of not having a certain dependency on the target machines. Figure: Setting the name filter based on server location  Used in combination there is a lot of power here to coordinate tens of build servers for multiple projects across multiple regions so your developers get the most out of your environment. Technorati Tags: ALM,TFBS,TFS 2010,TFS Admin

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  • What's the difference between Scala and Red Hat's Ceylon language?

    - by John Bryant
    Red Hat's Ceylon language has some interesting improvements over Java: The overall vision: learn from Java's mistakes, keep the good, ditch the bad The focus on readability and ease of learning/use Static Typing (find errors at compile time, not run time) No “special” types, everything is an object Named and Optional parameters (C# 4.0) Nullable types (C# 2.0) No need for explicit getter/setters until you are ready for them (C# 3.0) Type inference via the "local" keyword (C# 3.0 "var") Sequences (arrays) and their accompanying syntactic sugariness (C# 3.0) Straight-forward implementation of higher-order functions I don't know Scala but have heard it offers some similar advantages over Java. How would Scala compare to Ceylon in this respect?

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  • Project Coin: JSR 334 has a Proposed Final Draft

    - by darcy
    Reaching nearly the last phase of the JCP process, JSR 334 now has a proposed final draft. There have been only a few refinements to the specification since public review: Incorporated language changes into JLS proper. Forbid combining diamond and explicit type arguments to a generic constructor. Removed unusual protocol around Throwable.addSuppressed(null) and added a new constructor to Throwable to allow suppression to be disabled. Added disclaimers that OutOfMemoryError, NullPointerException, and ArithmeticException objects created by the JVM may have suppression disabled. Added thread safely requirements to Throwable.addSuppressed and Throwable.getSuppressed. Next up is the final approval ballot; almost there!

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  • How to sync files between local dir and remote dir without using an IDE?

    - by Moe Sweet
    I'm running windows 7 and I have a working dir in my PC. I have my staging server that I only have FTPS (Explicit) access to. What I want... Everytime I change something in my local dir, I want my remote dir synced via FTPS method alone. SVN, CVS, GIT is not an option. I tried notepad++, eclipse and Netbeans and all couldn't work. In general, I don't want to rely on an IDE to achieve this task. And I don't want to install anything funny like rsync and I don't want to write scripts.

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  • Goto for the Java Programming Language

    - by darcy
    Work on JDK 8 is well-underway, but we thought this late-breaking JEP for another language change for the platform couldn't wait another day before being published. Title: Goto for the Java Programming Language Author: Joseph D. Darcy Organization: Oracle. Created: 2012/04/01 Type: Feature State: Funded Exposure: Open Component: core/lang Scope: SE JSR: 901 MR Discussion: compiler dash dev at openjdk dot java dot net Start: 2012/Q2 Effort: XS Duration: S Template: 1.0 Reviewed-by: Duke Endorsed-by: Edsger Dijkstra Funded-by: Blue Sun Corporation Summary Provide the benefits of the time-testing goto control structure to Java programs. The Java language has a history of adding new control structures over time, the assert statement in 1.4, the enhanced for-loop in 1.5,and try-with-resources in 7. Having support for goto is long-overdue and simple to implement since the JVM already has goto instructions. Success Metrics The goto statement will allow inefficient and verbose recursive algorithms and explicit loops to be replaced with more compact code. The effort will be a success if at least twenty five percent of the JDK's explicit loops are replaced with goto's. Coordination with IDE vendors is expected to help facilitate this goal. Motivation The goto construct offers numerous benefits to the Java platform, from increased expressiveness, to more compact code, to providing new programming paradigms to appeal to a broader demographic. In JDK 8, there is a renewed focus on using the Java platform on embedded devices with more modest resources than desktop or server environments. In such contexts, static and dynamic memory footprint is a concern. One significant component of footprint is the code attribute of class files and certain classes of important algorithms can be expressed more compactly using goto than using other constructs, saving footprint. For example, to implement state machines recursively, some parties have asked for the JVM to support tail calls, that is, to perform a complex transformation with security implications to turn a method call into a goto. Such complicated machinery should not be assumed for an embedded context. A better solution is just to expose to the programmer the desired functionality, goto. The web has familiarized users with a model of traversing links among different HTML pages in a free-form fashion with some state being maintained on the side, such as login credentials, to effect behavior. This is exactly the programming model of goto and code. While in the past this has been derided as leading to "spaghetti code," spaghetti is a tasty and nutritious meal for programmers, unlike quiche. The invokedynamic instruction added by JSR 292 exposes the JVM's linkage operation to programmers. This is a low-level operation that can be leveraged by sophisticated programmers. Likewise, goto is a also a low-level operation that should not be hidden from programmers who can use more efficient idioms. Some may object that goto was consciously excluded from the original design of Java as one of the removed feature from C and C++. However, the designers of the Java programming languages have revisited these removals before. The enum construct was also left out only to be added in JDK 5 and multiple inheritance was left out, only to be added back by the virtual extension method methods of Project Lambda. As a living language, the needs of the growing Java community today should be used to judge what features are needed in the platform tomorrow; the language should not be forever bound by the decisions of the past. Description From its initial version, the JVM has had two instructions for unconditional transfer of control within a method, goto (0xa7) and goto_w (0xc8). The goto_w instruction is used for larger jumps. All versions of the Java language have supported labeled statements; however, only the break and continue statements were able to specify a particular label as a target with the onerous restriction that the label must be lexically enclosing. The grammar addition for the goto statement is: GotoStatement: goto Identifier ; The new goto statement similar to break except that the target label can be anywhere inside the method and the identifier is mandatory. The compiler simply translates the goto statement into one of the JVM goto instructions targeting the right offset in the method. Therefore, adding the goto statement to the platform is only a small effort since existing compiler and JVM functionality is reused. Other language changes to support goto include obvious updates to definite assignment analysis, reachability analysis, and exception analysis. Possible future extensions include a computed goto as found in gcc, which would replace the identifier in the goto statement with an expression having the type of a label. Testing Since goto will be implemented using largely existing facilities, only light levels of testing are needed. Impact Compatibility: Since goto is already a keyword, there are no source compatibility implications. Performance/scalability: Performance will improve with more compact code. JVMs already need to handle irreducible flow graphs since goto is a VM instruction.

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  • Does TDD lead to the good design?

    - by Eugen Martynov
    I'm in transition from "writing unit tests" state to TDD. I saw as Johannes Brodwall creates quite acceptable design from avoiding any of architecture phase before. I'll ask him soon if it was real improvisation or he had some thoughts upfront. I also clearly understand that everyone has experience that prevents to write explicit design bad patterns. But after participating in code retreat I hardly believe that writing test first could save us from mistakes. But I also believe that tests after code will lead to mistakes much faster. So this night question is asking for people who is using TDD for a long time share their experience about results of design without upfront thinking. If they really practice it and get mostly suitable design. Or it's my small understanding about TDD and probably agile.

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  • Book review: SQL Server Transaction Log Management

    - by Hugo Kornelis
    It was an offer I could not resist. I was promised a free copy of one of the newest books from Red Gate Books , SQL Server Transaction Log Management (by Tony Davis and Gail Shaw ), with the caveat that I should write a review after reading it. Mind you, not a commercial, “make sure we sell more copies” kind of review, but a review of my actual thoughts. Yes, I got explicit permission to be my usual brutally honest self. A total win/win for me! First, I get a free book – and free is always good,...(read more)

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  • How should an object that uses composition set its composed components?

    - by Casey
    After struggling with various problems and reading up on component-based systems and reading Bob Nystrom's excellent book "Game Programming Patterns" and in particular the chapter on Components I determined that this is a horrible idea: //Class intended to be inherited by all objects. Engine uses Objects exclusively. class Object : public IUpdatable, public IDrawable { public: Object(); Object(const Object& other); Object& operator=(const Object& rhs); virtual ~Object() =0; virtual void SetBody(const RigidBodyDef& body); virtual const RigidBody* GetBody() const; virtual RigidBody* GetBody(); //Inherited from IUpdatable virtual void Update(double deltaTime); //Inherited from IDrawable virtual void Draw(BITMAP* dest); protected: private: }; I'm attempting to refactor it into a more manageable system. Mr. Nystrom uses the constructor to set the individual components; CHANGING these components at run-time is impossible. It's intended to be derived and be used in derivative classes or factory methods where their constructors do not change at run-time. i.e. his Bjorne object is just a call to a factory method with a specific call to the GameObject constructor. Is this a good idea? Should the object have a default constructor and setters to facilitate run-time changes or no default constructor without setters and instead use a factory method? Given: class Object { public: //...See below for constructor implementation concerns. Object(const Object& other); Object& operator=(const Object& rhs); virtual ~Object() =0; //See below for Setter concerns IUpdatable* GetUpdater(); IDrawable* GetRenderer(); protected: IUpdatable* _updater; IDrawable* _renderer; private: }; Should the components be read-only and passed in to the constructor via: class Object { public: //No default constructor. Object(IUpdatable* updater, IDrawable* renderer); //...remainder is same as above... }; or Should a default constructor be provided and then the components can be set at run-time? class Object { public: Object(); //... SetUpdater(IUpdater* updater); SetRenderer(IDrawable* renderer); //...remainder is same as above... }; or both? class Object { public: Object(); Object(IUpdater* updater, IDrawable* renderer); //... SetUpdater(IUpdater* updater); SetRenderer(IDrawable* renderer); //...remainder is same as above... };

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  • SQL SERVER – Puzzle #1 – Querying Pattern Ranges and Wild Cards

    - by Pinal Dave
    Note: Read at the end of the blog post how you can get five Joes 2 Pros Book #1 and a surprise gift. I have been blogging for almost 7 years and every other day I receive questions about Querying Pattern Ranges. The most common way to solve the problem is to use Wild Cards. However, not everyone knows how to use wild card properly. SQL Queries 2012 Joes 2 Pros Volume 1 – The SQL Queries 2012 Hands-On Tutorial for Beginners Book On Amazon | Book On Flipkart Learn SQL Server get all the five parts combo kit Kit on Amazon | Kit on Flipkart Many people know wildcards are great for finding patterns in character data. There are also some special sequences with wildcards that can give you even more power. This series from SQL Queries 2012 Joes 2 Pros® Volume 1 will show you some of these cool tricks. All supporting files are available with a free download from the www.Joes2Pros.com web site. This example is from the SQL 2012 series Volume 1 in the file SQLQueries2012Vol1Chapter2.2Setup.sql. If you need help setting up then look in the “Free Videos” section on Joes2Pros under “Getting Started” called “How to install your labs” Querying Pattern Ranges The % wildcard character represents any number of characters of any length. Let’s find all first names that end in the letter ‘A’. By using the percentage ‘%’ sign with the letter ‘A’, we achieve this goal using the code sample below: SELECT * FROM Employee WHERE FirstName LIKE '%A' To find all FirstName values beginning with the letters ‘A’ or ‘B’ we can use two predicates in our WHERE clause, by separating them with the OR statement. Finding names beginning with an ‘A’ or ‘B’ is easy and this works fine until we want a larger range of letters as in the example below for ‘A’ thru ‘K’: SELECT * FROM Employee WHERE FirstName LIKE 'A%' OR FirstName LIKE 'B%' OR FirstName LIKE 'C%' OR FirstName LIKE 'D%' OR FirstName LIKE 'E%' OR FirstName LIKE 'F%' OR FirstName LIKE 'G%' OR FirstName LIKE 'H%' OR FirstName LIKE 'I%' OR FirstName LIKE 'J%' OR FirstName LIKE 'K%' The previous query does find FirstName values beginning with the letters ‘A’ thru ‘K’. However, when a query requires a large range of letters, the LIKE operator has an even better option. Since the first letter of the FirstName field can be ‘A’, ‘B’, ‘C’, ‘D’, ‘E’, ‘F’, ‘G’, ‘H’, ‘I’, ‘J’ or ‘K’, simply list all these choices inside a set of square brackets followed by the ‘%’ wildcard, as in the example below: SELECT * FROM Employee WHERE FirstName LIKE '[ABCDEFGHIJK]%' A more elegant example of this technique recognizes that all these letters are in a continuous range, so we really only need to list the first and last letter of the range inside the square brackets, followed by the ‘%’ wildcard allowing for any number of characters after the first letter in the range. Note: A predicate that uses a range will not work with the ‘=’ operator (equals sign). It will neither raise an error, nor produce a result set. --Bad query (will not error or return any records) SELECT * FROM Employee WHERE FirstName = '[A-K]%' Question: You want to find all first names that start with the letters A-M in your Customer table and end with the letter Z. Which SQL code would you use? a. SELECT * FROM Customer WHERE FirstName LIKE 'm%z' b. SELECT * FROM Customer WHERE FirstName LIKE 'a-m%z' c. SELECT * FROM Customer WHERE FirstName LIKE 'a-m%z' d. SELECT * FROM Customer WHERE FirstName LIKE '[a-m]%z' e. SELECT * FROM Customer WHERE FirstName LIKE '[a-m]z%' f. SELECT * FROM Customer WHERE FirstName LIKE '[a-m]%z' g. SELECT * FROM Customer WHERE FirstName LIKE '[a-m]z%' Contest Leave a valid answer before June 18, 2013 in the comment section. 5 winners will be selected from all the valid answers and will receive Joes 2 Pros Book #1. 1 Lucky person will get a surprise gift from Joes 2 Pros. The contest is open for all the countries where Amazon ships the book (USA, UK, Canada, India and many others). Special Note: Read all the options before you provide valid answer as there is a small trick hidden in answers. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • My First Iteration Zero

    - by onefloridacoder
    I recently watched a web cast that covered the idea of planning from the concept stage to the product backlog.  It was the first content I had seen related to Iteration Zero and it made a lot of sense from a planning and engagement perspective where the customer is concerned.  It illuminated some of the problems I’ve experienced with getting a large project of the ground.  The idea behind this is to just figure out get everyone to understand what needs to be constructed and to build the initial feature set from a *very* high level.  Once that happens other parts of the high level construction start to take place.  You end up with a feature list that describes what the business wants the system to do, and what it potentially may (or may not) interact with.  Low tech tools are used to create UI mockups that can be used as a starting point for some of the key UI pieces. Toward the end of the webcast they speaker introduced something that was new to me.  He referred to it as an executable skeleton or the steel thread.  The idea with this part of the webcast was to describe walking through the different mocked layers of the application.  Not all layers and collaborators are involved at this stage since it’s Iteration Zero, and each layer is either hard-coded or completely mocked to provide a 35K foot view of how the different layers layers work together.  So imagine two actors on each side of a layer diagram and the flow goes down from the upper left side down through a a consumer, thorough a service layer and then back up the service layer to the destination/actor. I would imagine much could be discussed moving through new/planned or existing/legacy layers, or a little of both to see what’s implied by the current high-level design. One part of the web cast has the business and design team creating the product box (think of your favorite cereal or toy box) with all of the features and even pictures laid out on the outside of the box.  The notion here is that if you handed this box to someone and told them your system was inside they would have an understanding of what the system would be able to do, or the features it could provide.    One of the interesting parts of the webcast was where the speaker described that he worked with a couple of groups in the same room and each group came up with a different product box – the point is that each group had a different idea of what the system was supposed to do.  At this point of the project I thought that to be valuable considering my experience has been that historically this has taken longer than a week to realize that the business unit and design teams see the high level solution differently.  Once my box is finished I plan on moving to the next stage of solution definition which is to plan the UI for this small application using Excel, to map out the UI elements.  I’m my own customer so it feels like cheating, but taking these slow deliberate steps have already provided a few learning opportunities.    So I resist the urge to load all of my user stories into my newly installed VS2010  TFS project and try to reduce or add to, the number of user stories and/or refine the high level estimates I’ve come up with so far.

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  • How should I make searching a relational database more efficient?

    - by Travis J
    This is in the scope of a web application. I have a database which has a few nested relations. There is a feature which depicts the history of a large chain of relations. It is essentially a data analysis feature. The issue is that in order to search, a large object graph must be loaded - the loading time for this object graph is not quick enough to be viable. The problem is that without loading the whole graph it makes searching from a single string nearly impossible. In order to search, explicit fields must be specified and the search data supplied. Is there a design pattern for exposing the data in a way which facilitates a single string search instead of having to explicitly define parameters?

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  • Gamification: designing cooperation in an RPG like game based on Scrum methodology

    - by Grzegorz Slawecki
    I have implemented with 3 friends a gamified system at my work (development company) which builds an fantasy rpg game over scrum project methodology. Generally, the tasks are the missions, each player is represented by a character. They earn XPs for completing tasks and they advance to the next levels which gives them badges, titles and (this is in planning phase) new privileges (e.g. priority in choosing tasks). Since the very beginning we try to do everything to avoid rivalisation between players because it would ruin the project if the players started to compete. There are no explicit leaderboards, we also plan to give bonuses for helping other players. I have a feeling that this is still not enough to really encourage cooperation. I would like to ask You for any ideas that come to Your mind that would help.

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  • Find related field in Dynamics AX

    - by DAXShekhar
    static void findRelatedFieldId(Args _args) {     SysDictTable    dictTable = new SysDictTable(tablenum(InventTrans));     int             i,j;     SysDictRelation dictRelation;     TableId         externId = tablenum(SalesLine);     IndexId         indexId;     ; // Search the explicit relations     for (i = 1; i <= dictTable.relationCnt(); ++i)     {         dictRelation = new SysDictRelation(dictTable.id());         dictRelation.loadNameRelation(dictTable.relation(i)); // If it is a 'relation' then you use externTable(), but for extended data types you use table() (see next block).         if (SysDictRelation::externId(dictRelation) == externId)         {             for (j =1; j <= dictRelation.lines(); j++)             {                 info(strfmt("%1", dictRelation.lineExternTableValue(j)));                 info(fieldid2name(dictRelation.externTable(),dictRelation.lineExternTableValue(j)));             }         }     }     info(strfmt("%1", dictRelation.loadFieldRelation(fieldnum(InventTrans, InventTransId)))); }

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  • Problems implementing a screen space shadow ray tracing shader

    - by Grieverheart
    Here I previously asked for the possibility of ray tracing shadows in screen space in a deferred shader. Several problems were pointed out. One of the most important problem is that only visible objects can cast shadows and objects between the camera and the shadow caster can interfere. Still I thought it'd be a fun experiment. The idea is to calculate the view coordinates of pixels and cast a ray to the light. The ray is then traced pixel by pixel to the light and its depth is compared with the depth at the pixel. If a pixel is in front of the ray, a shadow is casted at the original pixel. At first I thought that I could use the DDA algorithm in 2D to calculate the distance 't' (in p = o + t d, where o origin, d direction) to the next pixel and use it in the 3D ray equation to find the ray's z coordinate at that pixel's position. For the 2D ray, I would use the projected and biased 3D ray direction and origin. The idea was that 't' would be the same in both 2D and 3D equations. Unfortunately, this is not the case since the projection matrix is 4D. Thus, some tweak needs to be done to make this work this way. I would like to ask if someone knows of a way to do what I described above, i.e. from a 2D ray in texture coordinate space to get the 3D ray in screen space. I did implement a simple version of the idea which you can see in the following video: video here Shadows may seem a bit pixelated, but that's mostly because of the size of the step in 't' I chose. And here is the shader: #version 330 core uniform sampler2D DepthMap; uniform vec2 projAB; uniform mat4 projectionMatrix; const vec3 light_p = vec3(-30.0, 30.0, -10.0); noperspective in vec2 pass_TexCoord; smooth in vec3 viewRay; layout(location = 0) out float out_AO; vec3 CalcPosition(void){ float depth = texture(DepthMap, pass_TexCoord).r; float linearDepth = projAB.y / (depth - projAB.x); vec3 ray = normalize(viewRay); ray = ray / ray.z; return linearDepth * ray; } void main(void){ vec3 origin = CalcPosition(); if(origin.z < -60) discard; vec2 pixOrigin = pass_TexCoord; //tex coords vec3 dir = normalize(light_p - origin); vec2 texel_size = vec2(1.0 / 600.0); float t = 0.1; ivec2 pixIndex = ivec2(pixOrigin / texel_size); out_AO = 1.0; while(true){ vec3 ray = origin + t * dir; vec4 temp = projectionMatrix * vec4(ray, 1.0); vec2 texCoord = (temp.xy / temp.w) * 0.5 + 0.5; ivec2 newIndex = ivec2(texCoord / texel_size); if(newIndex != pixIndex){ float depth = texture(DepthMap, texCoord).r; float linearDepth = projAB.y / (depth - projAB.x); if(linearDepth > ray.z + 0.1){ out_AO = 0.2; break; } pixIndex = newIndex; } t += 0.5; if(texCoord.x < 0 || texCoord.x > 1.0 || texCoord.y < 0 || texCoord.y > 1.0) break; } } As you can see, here I just increment 't' by some arbitrary factor, calculate the 3D ray and project it to get the pixel coordinates, which is not really optimal. Hopefully, I would like to optimize the code as much as possible and compare it with shadow mapping and how it scales with the number of lights. PS: Keep in mind that I reconstruct position from depth by interpolating rays through a full screen quad.

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  • Why, on iOS, is glRenderbufferStorage appearing to fail?

    - by dugla
    On an iOS device (iPad) I decided to change the storage for my renderbuffer from the CAEAGLLayer that backs the view to explicit storage via glRenderbufferStorage. Sadly, the following code fails to result in a valid FBO. Can someone please tell me what I missed?: glGenFramebuffers(1, &m_framebuffer); glBindFramebuffer(GL_FRAMEBUFFER, m_framebuffer); glGenRenderbuffers(1, &m_colorbuffer); glBindRenderbuffer(GL_RENDERBUFFER, m_colorbuffer); GLsizei width = (GLsizei)layer.bounds.size.width; GLsizei height = (GLsizei)layer.bounds.size.height; glRenderbufferStorage(m_colorbuffer, GL_RGBA8_OES, width, height); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, m_colorbuffer); Note: The layer size is valid and correct. This is solid production working rendering code. The only change I am making is the line glRenderbufferStorage(...) previously I did: [m_context renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer] Thanks, Doug

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  • A deadlock was detected while trying to lock variables in SSIS

    Error: 0xC001405C at SQL Log Status: A deadlock was detected while trying to lock variables "User::RowCount" for read/write access. A lock cannot be acquired after 16 attempts. The locks timed out. Have you ever considered variable locking when building your SSIS packages? I expect many people haven’t just because most of the time you never see an error like the one above. I’ll try and explain a few key concepts about variable locking and hopefully you never will see that error. First of all, what is all this variable locking all about? Put simply SSIS variables have to be locked before they can be accessed, and then of course unlocked once you have finished with them. This is baked into SSIS, presumably to reduce the risk of race conditions, but with that comes some additional overhead in that you need to be careful to avoid lock conflicts in some scenarios. The most obvious place you will come across any hint of locking (no pun intended) is the Script Task or Script Component with their ReadOnlyVariables and ReadWriteVariables properties. These two properties allow you to enter lists of variables to be used within the task, or to put it another way, these lists of variables to be locked, so that they are available within the task. During the task pre-execute phase the variables and locked, you then use them during the execute phase when you code is run, and then unlocked for you during the post-execute phase. So by entering the variable names in one of the two list, the locking is taken care of for you, and you just read and write to the Dts.Variables collection that is exposed in the task for the purpose. As you can see in the image above, the variable PackageInt is specified, which means when I write the code inside that task I don’t have to worry about locking at all, as shown below. public void Main() { // Set the variable value to something new Dts.Variables["PackageInt"].Value = 199; // Raise an event so we can play in the event handler bool fireAgain = true; Dts.Events.FireInformation(0, "Script Task Code", "This is the script task raising an event.", null, 0, ref fireAgain); Dts.TaskResult = (int)ScriptResults.Success; } As you can see as well as accessing the variable, hassle free, I also raise an event. Now consider a scenario where I have an event hander as well as shown below. Now what if my event handler uses tries to use the same variable as well? Well obviously for the point of this post, it fails with the error quoted previously. The reason why is clearly illustrated if you consider the following sequence of events. Package execution starts Script Task in Control Flow starts Script Task in Control Flow locks the PackageInt variable as specified in the ReadWriteVariables property Script Task in Control Flow executes script, and the On Information event is raised The On Information event handler starts Script Task in On Information event handler starts Script Task in On Information event handler attempts to lock the PackageInt variable (for either read or write it doesn’t matter), but will fail because the variable is already locked. The problem is caused by the event handler task trying to use a variable that is already locked by the task in Control Flow. Events are always raised synchronously, therefore the task in Control Flow that is raising the event will not regain control until the event handler has completed, so we really do have un-resolvable locking conflict, better known as a deadlock. In this scenario we can easily resolve the problem by managing the variable locking explicitly in code, so no need to specify anything for the ReadOnlyVariables and ReadWriteVariables properties. public void Main() { // Set the variable value to something new, with explicit lock control Variables lockedVariables = null; Dts.VariableDispenser.LockOneForWrite("PackageInt", ref lockedVariables); lockedVariables["PackageInt"].Value = 199; lockedVariables.Unlock(); // Raise an event so we can play in the event handler bool fireAgain = true; Dts.Events.FireInformation(0, "Script Task Code", "This is the script task raising an event.", null, 0, ref fireAgain); Dts.TaskResult = (int)ScriptResults.Success; } Now the package will execute successfully because the variable lock has already been released by the time the event is raised, so no conflict occurs. For those of you with a SQL Engine background this should all sound strangely familiar, and boils down to getting in and out as fast as you can to reduce the risk of lock contention, be that SQL pages or SSIS variables. Unfortunately we cannot always manage the locking ourselves. The Execute SQL Task is very often used in conjunction with variables, either to pass in parameter values or get results out. Either way the task will manage the locking for you, and will fail when it cannot lock the variables it requires. The scenario outlined above is clear cut deadlock scenario, both parties are waiting on each other, so it is un-resolvable. The mechanism used within SSIS isn’t actually that clever, and whilst the message says it is a deadlock, it really just means it tried a few times, and then gave up. The last part of the error message is actually the most accurate in terms of the failure, A lock cannot be acquired after 16 attempts. The locks timed out.  Now this may come across as a recommendation to always manage locking manually in the Script Task or Script Component yourself, but I think that would be an overreaction. It is more of a reminder to be aware that in high concurrency scenarios, especially when sharing variables across multiple objects, locking is important design consideration. Update – Make sure you don’t try and use explicit locking as well as leaving the variable names in the ReadOnlyVariables and ReadWriteVariables lock lists otherwise you’ll get the deadlock error, you cannot lock a variable twice!

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