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  • Why is Harvest being purchased at all?

    - by Mike Caron
    Does your work environment use Harvest SCM? I've used this now at two different locations and find it appalling. In one situation I wrote a conversion script so I could use CVS locally and then daily import changes to the Harvest system while I was sleeping. The corp was fanatic about using Harvest, despite 80% of the programmers crying for something different. It was needlessly complicated, slow and heavy. It is now a job requirement for me that Harvest is not in use where I work. Has anyone else used Harvest before? What's your experience? As bad as mine? Did you employ other, different workarounds? Why is this product still purchased today?

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  • Database that accesses a website.?

    - by Alec
    Hi Guys What application should I use that is able to automatically access a website to gather information? Basically I have a database that completes calculations for me; however I have to manually gather the parameters from a website and input these into my database. What I would like is have an application that will take my input say the name of a product, access the website, add this name into a search box on a website, complete the search and then extract the desired information from the web page returning the results to my application to complete the calculation thus presenting me with the result. This is a little out of my depth but I’m willing to learn no matter how complicated the software. Cheers for your help.

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  • Usage scenario for svn branches

    - by Paul Knopf
    I have a product that I distribute to my clients. Each client needs some UI customization. I want each client to be able to get updated with new version easily. Can I create a project in svn that serves as a "base project", and then create branches for each client? With that said, will I then be able to commit changes in a branch to the branch, with the option of pushing that change to the core? Can I also perform and "update" command in a branch that will only update changes to the core?

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  • jQuery noob: $("this").parent().attr("id",newId); troubles.

    - by Kyle Sevenoaks
    Hi, I have this code which I am trying to change the ID of on.hover. <span id="slidingProd"> <a href="{link controller=order action=addToCart id=$product.ID returnPath=true}" rel="nofollow" class="addToCart" title="Bestill" onclick="addToBasket(); return false;" id="fly_to_basket">&nbsp;</a> </span> I tried to use this jQuery, but it doesn't change the ID. $(function() { $("#fly_to_basket").hover(function() { $(this).parent().attr("id",slidingprod(1)); }); $("#fly_to_basket").hover(function() { $(this).attr("onclick",addToBasket(1)); }); What am I doing wrong? Thanks :)

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  • Interview Q: given an array of numbers, return array of products of all other numbers (no division)

    - by polygenelubricants
    I was asked this question in a job interview, and I'd like to know how others would solve it. I'm most comfortable with Java, but solutions in other languages are welcome. Given an array of numbers, nums, return an array of numbers products, where products[i] is the product of all nums[j], j != i. Input : [1, 2, 3, 4, 5] Output: [(2*3*4*5), (1*3*4*5), (1*2*4*5), (1*2*3*5), (1*2*3*4)] = [120, 60, 40, 30, 24] You must do this in O(N) without using division.

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  • question about Littles Law

    - by davit-datuashvili
    I know that Little's Law states (paraphrased): the average number of things in a system is the product of the average rate at which things leave the system and the average time each one spends in the system, or: n=x*(r+z); x-throughput r-response time z-think time r+z - average response time now i have question about a problem from programming pearls: Suppose that system makes 100 disk accesses to process a transaction (although some systems require fewer, some systems will require several hundred disk access per transaction). How many transactions per hour per disk can the system handle? please help

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  • Can I sell video and music in iPhone app via in-app purchase

    - by initialz
    Hi, I'm going to sell some video and music (which I have right to use and sell) in iPhone app. But I'm not sure whether this is allowed by Apple. The plan is to create a consumable in-app purchase product and ask user to pay it when visit the individual video page. After successful purchase, user can download or view it online without any limitation. Server side will also remember the purchase status so the user won't be asked to pay when he visit this vide page next time. So, does anyone have experience on this kind of business and give me some suggestions? Thanks a lot!

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  • Sphinx without using an auto_increment id

    - by squeeks
    I am current in planning on creating a big database (2+ million rows) with a variety of data from separate sources. I would like to avoid structuring the database around auto_increment ids to help prevent against sync issues with replication, and also because each item inserted will have a alphanumeric product code that is guaranteed to be unique - it seems to me more sense to use that instead. I am looking at a search engine to index this database with Sphinx looking rather appealing due to its design around indexing relational databases. However, looking at various tutorials and documentation seems to show database designs being dependent on an auto_increment field in one form or another and a rather bold statement in the documentation saying that document ids must be 32/64bit integers only or things break. Is there a way to have a database indexed by Sphinx without auto_increment fields as the id?

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  • JQuery updating label

    - by Zaps
    Hi, I have 2 textboxes and a label on my page. The 2 textboxes will contain numeric values. The label text will be the product of the 2 textbox values. Is there a way to do this using JQuery so that the value can get updated without having to do a postback? Also the textboxes may contain values with commas in it: e.g. 10,000. Is there a way I can extract the number from this so that it can be used to calculate the label value. Thanks in advance, Zaps

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  • How to get the Drive letter and Mount Path - MSDN

    - by new
    Hello all, I get the devices list from the system using SetupDiGetClassDevs Function - MSDN. Also i can able to get the vendor id and product id from the devices. But i cant able to get the drive letter and the mount path For Example if i plug the usb drive means , i have to get the drive letter like "G:/" Please help me to get the drive letter and mount path for the devices if (SetupDiEnumDeviceInterfaces(hDevInfo, NULL,&GUID_DEVINTERFACE_USB_DEVICE,i,&Interface_Info)) { wprintf(L"\tDeviccvcvcveInstanceId : %d\n", i); pspdidd->cbSize = sizeof(*pspdidd); SP_DEVICE_INTERFACE_DETAIL_DATA *pDetData = NULL; DWORD dwDetDataSize = sizeof (SP_DEVICE_INTERFACE_DETAIL_DATA) + 256; pDetData = (SP_DEVICE_INTERFACE_DETAIL_DATA*) malloc (dwDetDataSize); pDetData->cbSize = sizeof (SP_DEVICE_INTERFACE_DETAIL_DATA); SetupDiGetDeviceInterfaceDetail(hDevInfo,&Interface_Info,pDetData,dwDetDataSize, NULL,&DeviceInfoData); qDebug ()<<QString::fromWCharArray( pDetData->DevicePath ); }

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  • list within a list

    - by atm atm
    I'm working on this problem, but I cannot figure out the second part. I tried using reverse list but it did not work out how I planned it. Given a list L (e.g. [1,2,3,4]), write a program that generates the following nested lists: L1 = [[1],[1,2],[1,2,3],[1,2,3,4]], L2 = [[4],[3,4],[2,3,4],[1,2,3,4]]. My code that I have so far: mylist=[,1,2,3,4] print("Orginal list L=",mylist) n=len(mylist) l1=[] l2=[] for x in range(1,n+1,1): l1.append(mylist[0:x]) print("L1=",l1) #prints final product of l1 mylist.reverse() #this is where i get messed up for x in range(1,n+1,1): l2.append(mylist[0:x]) print("L2=",l2)

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  • Magento search not returning expected results

    - by spdaly
    Our site, www.wearport.com (sorry - I'm not trying to post this for links stuffing/ad'ing! It's necessary for this question), uses search for users to find products in our catalog. We use the search widget in the admin to gauge how successful users are with searching for products. "Missed searches" are revised with synonyms and redirects as they are identified. The issue is that many of the nominal searches don't work correctly. By "nominal" I mean terms that are prominent in the product - title, description, etc. If you search "fleece" it brings up sweatshirts and fleece, but the fleece is item 9 instead of I know that more sophisticated indexing will be available in later releases, but I would think that this should work correctly OOTB. Do I need to do further configuration of code and/or database?

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  • Optimizing MySQL queries with IN operator

    - by Arkadiusz Kondas
    I have a MySQL database with a fairly large table where the products are. Each of them has its own id and categoryId field where there is a category id belongs to this product. Now I have a query that pulls out products from given categories such as: SELECT * FROM products WHERE categoryId IN ( 1, 2, 3, 4, 5, 34, 6, 7, 8, 9, 10, 11, 12 ) Of course, come a WHERE clause and ORDER BY sort but not in this thing. Let's say that these products is 250k and the visits are over 100k per day. Under such conditions in the table slow_log registered weight of these queries with large generation time. Do you have any ideas how to optimize the given problem? Table engine is MyISAM.

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  • Can you ask Google how common a search is?

    - by John
    I'm not familiar with Google Analytics but I think you can use it to see how many people get to your site using different search strings. But if you don't yet have the site, can you simply ask Google how popular a search is? For instance say you're choosing a new product name/slogan/etc. First of all, you want to see if that is already very crowded, which is easy through just Googling it. But now you might want to see if anyone is actually searching for this... an ideal situation would be to find a search-string lots of people are using, which doesn't put your competitors on the #1 spot. Is this possible? Not exactly programming-related, but closely related to web-development IMO... please vote to close if you disagree, I won't be offended!

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  • Unable to center text in IE but works in firefox

    - by greenpool
    Can somebody point out where I'm going wrong with the following code. Text inside td elements need to be centered except for Summary and Experience. This only appears to work in Firefox/chrome. In IE8 all td text are displayed as left-justified. No matter what I try it doesn't center it. Any particular reason why this would happen? Thanks. css #viewAll { font-family:"Trebuchet MS", Arial, Helvetica, sans-serif; width:100%; border-collapse:collapse; margin-left:10px; table-layout: fixed; } #viewAll td, #viewAll th { font-size:1.1em; border:1px solid #98bf21; word-wrap:break-word; text-align:center; overflow:hidden; } #viewAll tbody td{ padding:2px; } #viewAll th { font-size:1.1em; padding-top:5px; padding-bottom:4px; background-color:#A7C942; color:#ffffff; } table <?php echo '<table id="viewAll" class="tablesorter">'; echo '<thead>'; echo '<tr align="center">'; echo '<th style="width:70px;">Product</th>'; echo '<th style="width:105px;">Prob</th>'; echo '<th style="width:105px;">I</th>'; echo '<th style="width:60px;">Status</th>'; echo '<th style="width:120px;">Experience</th>'; echo '<th style="width:200px;">Technical Summary</th>'; echo '<th style="width:80px;">Record Created</th>'; echo '<th style="width:80px;">Record Updated</th>'; echo '<th style="width:50px;">Open</th>'; echo '</tr>'; echo '</thead>'; echo '<tbody>'; while ($data=mysqli_fetch_array($result)){ #limiting the summary text displayed in the table $limited_summary = (strlen($data['summary']) > 300) ? substr(($data['summary']),0,300) . '...' : $data['summary']; $limited_exp = (strlen($data['exp']) > 300) ? substr(($data['exp']),0,300) . '...' : $data['exp']; echo '<tr align="center"> <td style="width:70px; text-align:center;">'.$data['product'].'</td>'; //if value is '-' do not display as link if ($data['prob'] != '-'){ echo '<td style="width:105px;">'.$data['prob'].'</a></td>'; } else{ echo '<td style="width:105px; ">'.$data['prob'].'</td>'; } if ($data['i'] != '-'){ echo '<td style="width:105px; ">'.$data['i'].'</a></td>'; } else{ echo '<td style="width:105px; ">'.$data['i'].'</td>'; } echo'<td style="width:40px; " >'.$data['status'].'</td> <td style="width:120px; text-align:left;">'.$limited_cust_exp.'</td> <td style="width:200px; text-align:left;">'.$limited_summary.'</td> <td style="width:80px; ">'.$data['created'].'</td> <td style="width:80px; ">'.$data['updated'].'</td>'; if (isset($_SESSION['username'])){ echo '<td style="width:50px; "> <form action="displayRecord.php" method="get">'.' <input type="hidden" name="id" value="'. $data['id'].'" style="text-decoration: none" /><input type="submit" value="Open" /></form></td>'; }else{ echo '<td style="width:50px; "> <form action="displayRecord.php" method="get">'.' <input type="hidden" name="id" value="'. $data['id'].'" style="text-decoration: none" /><input type="submit" value="View" /></form></td>'; } echo '</tr>'; }#end of while echo '</tbody>'; echo '</table>'; ?>

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  • access a property via string with array in php?

    - by sprugman
    (This is in drupal, but I don't really think that matters.) I have a big list of properties that I need to map between two objects, and in one, the value that I need to map is buried inside an array. I'm hoping to avoid hard-coding the property names in the code. If I have a class like this: class Product { public $colors, $sizes; } I can access the properties like this: $props = array('colors', 'sizes'); foreach ($props as $p) { $this->$p = $other_object->$p; } As far as I can tell, if each of the properties on the left are an array, I can't do this: foreach ($props as $p) { $this->$p[0]['value'] = $other_object->$p; } Is that correct, or am I missing some clever way around this?

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  • how do I disable options based on the previous selection?

    - by 3r1c
    I have three drop-down menus for each sample shirt; product, colour and grade. Not all products are available in all colours and/or grades. I would like to disable the options that are not available based on the users selection. I've tried using this answer here (using a radio select). Unfortunately, I can't get it to work with an option-selected input. This is what I'm working on - quartus.ca/select-options.html Any guidance would be appreciated.

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  • Dynamic web widget

    - by user1824996
    My vendor offers a widget creation service where I can login to their page, set initial values of a search form, after the save button is clicked, I can copy & paste the script code on my website to display a product search result widget. I am thinking to change this static widget to a dynamic one. Since my programming knowledge is limited, can experts tell me if it's possible to login https remotely (using cURL) and set search form values equal to values on my page (every time my page content changes, it will change the form value), then save the form. So the widget script I pasted on my page will always be refreshed to new search result. So the issue will involve cross domain, form submission & server/browser communication. I know a little jQuery, PHP, Ajax, cURL but so far I stuck with just having an idea but not really sure how to implement it.

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  • Multi-tenant ASP.NET MVC – Introduction

    - by zowens
    I’ve read a few different blogs that talk about multi-tenancy and how to resolve some of the issues surrounding multi-tenancy. What I’ve come to realize is that these implementations overcomplicate the issues and give only a muddy implementation! I’ve seen some really illogical code out there. I have recently been building a multi-tenancy framework for internal use at eagleenvision.net. Through this process, I’ve realized a few different techniques to make building multi-tenant applications actually quite easy. I will be posting a few different entries over the issue and my personal implementation. In this first post, I will discuss what multi-tenancy means and how my implementation will be structured.   So what’s the problem? Here’s the deal. Multi-tenancy is basically a technique of code-reuse of web application code. A multi-tenant application is an application that runs a single instance for multiple clients. Here the “client” is different URL bindings on IIS using ASP.NET MVC. The problem with different instances of the, essentially, same application is that you have to spin up different instances of ASP.NET. As the number of running instances of ASP.NET grows, so does the memory footprint of IIS. Stack Exchange shifted its architecture to multi-tenancy March. As the blog post explains, multi-tenancy saves cost in terms of memory utilization and physical disc storage. If you use the same code base for many applications, multi-tenancy just makes sense. You’ll reduce the amount of work it takes to synchronize the site implementations and you’ll thank your lucky stars later for choosing to use one application for multiple sites. Multi-tenancy allows the freedom of extensibility while relying on some pre-built code.   You’d think this would be simple. I have actually seen a real lack of reference material on the subject in terms of ASP.NET MVC. This is somewhat surprising given the number of users of ASP.NET MVC. However, I will certainly fill the void ;). Implementing a multi-tenant application takes a little thinking. It’s not straight-forward because the possibilities of implementation are endless. I have yet to see a great implementation of a multi-tenant MVC application. The only one that comes close to what I have in mind is Rob Ashton’s implementation (all the entries are listed on this page). There’s some really nasty code in there… something I’d really like to avoid. He has also written a library (MvcEx) that attempts to aid multi-tenant development. This code is even worse, in my honest opinion. Once I start seeing Reflection.Emit, I have to assume the worst :) In all seriousness, if his implementation makes sense to you, use it! It’s a fine implementation that should be given a look. At least look at the code. I will reference MvcEx going forward as a comparison to my implementation. I will explain why my approach differs from MvcEx and how it is better or worse (hopefully better).   Core Goals of my Multi-Tenant Implementation The first, and foremost, goal is to use Inversion of Control containers to my advantage. As you will see throughout this series, I pass around containers quite frequently and rely on their use heavily. I will be using StructureMap in my implementation. However, you could probably use your favorite IoC tool instead. <RANT> However, please don’t be stupid and abstract your IoC tool. Each IoC is powerful and by abstracting the capabilities, you’re doing yourself a real disservice. Who in the world swaps out IoC tools…? No one!</RANT> (It had to be said.) I will outline some of the goodness of StructureMap as we go along. This is really an invaluable tool in my tool belt and simple to use in my multi-tenant implementation. The second core goal is to represent a tenant as easily as possible. Just as a dependency container will be a first-class citizen, so will a tenant. This allows us to easily extend and use tenants. This will also allow different ways of “plugging in” tenants into your application. In my implementation, there will be a single dependency container for a single tenant. This will enable isolation of the dependencies of the tenant. The third goal is to use composition as a means to delegate “core” functions out to the tenant. More on this later.   Features In MvcExt, “Modules” are a code element of the infrastructure. I have simplified this concept and have named this “Features”. A feature is a simple element of an application. Controllers can be specified to have a feature and actions can have “sub features”. Each tenant can select features it needs and the other features will be hidden to the tenant’s users. My implementation doesn’t require something to be a feature. A controller can be common to all tenants. For example, (as you will see) I have a “Content” controller that will return the CSS, Javascript and Images for a tenant. This is common logic to all tenants and shouldn’t be hidden or considered a “feature”; Content is a core component.   Up next My next post will be all about the code. I will reveal some of the foundation to the way I do multi-tenancy. I will have posts dedicated to Foundation, Controllers, Views, Caching, Content and how to setup the tenants. Each post will be in-depth about the issues and implementation details, while adhering to my core goals outlined in this post. As always, comment with questions of DM me on twitter or send me an email.

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  • Fixing Robocopy for SQL Server Jobs

    - by Most Valuable Yak (Rob Volk)
    Robocopy is one of, if not the, best life-saving/greatest-thing-since-sliced-bread command line utilities ever to come from Microsoft.  If you're not using it already, what are you waiting for? Of course, being a Microsoft product, it's not exactly perfect. ;)  Specifically, it sets the ERRORLEVEL to a non-zero value even if the copy is successful.  This causes a problem in SQL Server job steps, since non-zero ERRORLEVELs report as failed. You can work around this by having your SQL job go to the next step on failure, but then you can't determine if there was a genuine error.  Plus you still see annoying red X's in your job history.  One way I've found to avoid this is to use a batch file that runs Robocopy, and I add some commands after it (in red): robocopy d:\backups \\BackupServer\BackupFolder *.bak rem suppress successful robocopy exit statuses, only report genuine errors (bitmask 16 and 8 settings)set/A errlev="%ERRORLEVEL% & 24" rem exit batch file with errorlevel so SQL job can succeed or fail appropriatelyexit/B %errlev% (The REM statements are simply comments and don't need to be included in the batch file) The SET command lets you use expressions when you use the /A switch.  So I set an environment variable "errlev" to a bitwise AND with the ERRORLEVEL value. Robocopy's exit codes use a bitmap/bitmask to specify its exit status.  The bits for 1, 2, and 4 do not indicate any kind of failure, but 8 and 16 do.  So by adding 16 + 8 to get 24, and doing a bitwise AND, I suppress any of the other bits that might be set, and allow either or both of the error bits to pass. The next step is to use the EXIT command with the /B switch to set a new ERRORLEVEL value, using the "errlev" variable.  This will now return zero (unless Robocopy had real errors) and allow your SQL job step to report success. This technique should also work for other command-line utilities.  The only issues I've found is that it requires the commands to be part of a batch file, so if you use Robocopy directly in your SQL job step you'd need to place it in a batch.  If you also have multiple Robocopy calls, you'll need to place the SET/A command ONLY after the last one.  You'd therefore lose any errors from previous calls, unless you use multiple "errlev" variables and AND them together. (I'll leave this as an exercise for the reader) The SET/A syntax also permits other kinds of expressions to be calculated.  You can get a full list by running "SET /?" on a command prompt.

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  • West Wind WebSurge - an easy way to Load Test Web Applications

    - by Rick Strahl
    A few months ago on a project the subject of load testing came up. We were having some serious issues with a Web application that would start spewing SQL lock errors under somewhat heavy load. These sort of errors can be tough to catch, precisely because they only occur under load and not during typical development testing. To replicate this error more reliably we needed to put a load on the application and run it for a while before these SQL errors would flare up. It’s been a while since I’d looked at load testing tools, so I spent a bit of time looking at different tools and frankly didn’t really find anything that was a good fit. A lot of tools were either a pain to use, didn’t have the basic features I needed, or are extravagantly expensive. In  the end I got frustrated enough to build an initially small custom load test solution that then morphed into a more generic library, then gained a console front end and eventually turned into a full blown Web load testing tool that is now called West Wind WebSurge. I got seriously frustrated looking for tools every time I needed some quick and dirty load testing for an application. If my aim is to just put an application under heavy enough load to find a scalability problem in code, or to simply try and push an application to its limits on the hardware it’s running I shouldn’t have to have to struggle to set up tests. It should be easy enough to get going in a few minutes, so that the testing can be set up quickly so that it can be done on a regular basis without a lot of hassle. And that was the goal when I started to build out my initial custom load tester into a more widely usable tool. If you’re in a hurry and you want to check it out, you can find more information and download links here: West Wind WebSurge Product Page Walk through Video Download link (zip) Install from Chocolatey Source on GitHub For a more detailed discussion of the why’s and how’s and some background continue reading. How did I get here? When I started out on this path, I wasn’t planning on building a tool like this myself – but I got frustrated enough looking at what’s out there to think that I can do better than what’s available for the most common simple load testing scenarios. When we ran into the SQL lock problems I mentioned, I started looking around what’s available for Web load testing solutions that would work for our whole team which consisted of a few developers and a couple of IT guys both of which needed to be able to run the tests. It had been a while since I looked at tools and I figured that by now there should be some good solutions out there, but as it turns out I didn’t really find anything that fit our relatively simple needs without costing an arm and a leg… I spent the better part of a day installing and trying various load testing tools and to be frank most of them were either terrible at what they do, incredibly unfriendly to use, used some terminology I couldn’t even parse, or were extremely expensive (and I mean in the ‘sell your liver’ range of expensive). Pick your poison. There are also a number of online solutions for load testing and they actually looked more promising, but those wouldn’t work well for our scenario as the application is running inside of a private VPN with no outside access into the VPN. Most of those online solutions also ended up being very pricey as well – presumably because of the bandwidth required to test over the open Web can be enormous. When I asked around on Twitter what people were using– I got mostly… crickets. Several people mentioned Visual Studio Load Test, and most other suggestions pointed to online solutions. I did get a bunch of responses though with people asking to let them know what I found – apparently I’m not alone when it comes to finding load testing tools that are effective and easy to use. As to Visual Studio, the higher end skus of Visual Studio and the test edition include a Web load testing tool, which is quite powerful, but there are a number of issues with that: First it’s tied to Visual Studio so it’s not very portable – you need a VS install. I also find the test setup and terminology used by the VS test runner extremely confusing. Heck, it’s complicated enough that there’s even a Pluralsight course on using the Visual Studio Web test from Steve Smith. And of course you need to have one of the high end Visual Studio Skus, and those are mucho Dinero ($$$) – just for the load testing that’s rarely an option. Some of the tools are ultra extensive and let you run analysis tools on the target serves which is useful, but in most cases – just plain overkill and only distracts from what I tend to be ultimately interested in: Reproducing problems that occur at high load, and finding the upper limits and ‘what if’ scenarios as load is ramped up increasingly against a site. Yes it’s useful to have Web app instrumentation, but often that’s not what you’re interested in. I still fondly remember early days of Web testing when Microsoft had the WAST (Web Application Stress Tool) tool, which was rather simple – and also somewhat limited – but easily allowed you to create stress tests very quickly. It had some serious limitations (mainly that it didn’t work with SSL),  but the idea behind it was excellent: Create tests quickly and easily and provide a decent engine to run it locally with minimal setup. You could get set up and run tests within a few minutes. Unfortunately, that tool died a quiet death as so many of Microsoft’s tools that probably were built by an intern and then abandoned, even though there was a lot of potential and it was actually fairly widely used. Eventually the tools was no longer downloadable and now it simply doesn’t work anymore on higher end hardware. West Wind Web Surge – Making Load Testing Quick and Easy So I ended up creating West Wind WebSurge out of rebellious frustration… The goal of WebSurge is to make it drop dead simple to create load tests. It’s super easy to capture sessions either using the built in capture tool (big props to Eric Lawrence, Telerik and FiddlerCore which made that piece a snap), using the full version of Fiddler and exporting sessions, or by manually or programmatically creating text files based on plain HTTP headers to create requests. I’ve been using this tool for 4 months now on a regular basis on various projects as a reality check for performance and scalability and it’s worked extremely well for finding small performance issues. I also use it regularly as a simple URL tester, as it allows me to quickly enter a URL plus headers and content and test that URL and its results along with the ability to easily save one or more of those URLs. A few weeks back I made a walk through video that goes over most of the features of WebSurge in some detail: Note that the UI has slightly changed since then, so there are some UI improvements. Most notably the test results screen has been updated recently to a different layout and to provide more information about each URL in a session at a glance. The video and the main WebSurge site has a lot of info of basic operations. For the rest of this post I’ll talk about a few deeper aspects that may be of interest while also giving a glance at how WebSurge works. Session Capturing As you would expect, WebSurge works with Sessions of Urls that are played back under load. Here’s what the main Session View looks like: You can create session entries manually by individually adding URLs to test (on the Request tab on the right) and saving them, or you can capture output from Web Browsers, Windows Desktop applications that call services, your own applications using the built in Capture tool. With this tool you can capture anything HTTP -SSL requests and content from Web pages, AJAX calls, SOAP or REST services – again anything that uses Windows or .NET HTTP APIs. Behind the scenes the capture tool uses FiddlerCore so basically anything you can capture with Fiddler you can also capture with Web Surge Session capture tool. Alternately you can actually use Fiddler as well, and then export the captured Fiddler trace to a file, which can then be imported into WebSurge. This is a nice way to let somebody capture session without having to actually install WebSurge or for your customers to provide an exact playback scenario for a given set of URLs that cause a problem perhaps. Note that not all applications work with Fiddler’s proxy unless you configure a proxy. For example, .NET Web applications that make HTTP calls usually don’t show up in Fiddler by default. For those .NET applications you can explicitly override proxy settings to capture those requests to service calls. The capture tool also has handy optional filters that allow you to filter by domain, to help block out noise that you typically don’t want to include in your requests. For example, if your pages include links to CDNs, or Google Analytics or social links you typically don’t want to include those in your load test, so by capturing just from a specific domain you are guaranteed content from only that one domain. Additionally you can provide url filters in the configuration file – filters allow to provide filter strings that if contained in a url will cause requests to be ignored. Again this is useful if you don’t filter by domain but you want to filter out things like static image, css and script files etc. Often you’re not interested in the load characteristics of these static and usually cached resources as they just add noise to tests and often skew the overall url performance results. In my testing I tend to care only about my dynamic requests. SSL Captures require Fiddler Note, that in order to capture SSL requests you’ll have to install the Fiddler’s SSL certificate. The easiest way to do this is to install Fiddler and use its SSL configuration options to get the certificate into the local certificate store. There’s a document on the Telerik site that provides the exact steps to get SSL captures to work with Fiddler and therefore with WebSurge. Session Storage A group of URLs entered or captured make up a Session. Sessions can be saved and restored easily as they use a very simple text format that simply stored on disk. The format is slightly customized HTTP header traces separated by a separator line. The headers are standard HTTP headers except that the full URL instead of just the domain relative path is stored as part of the 1st HTTP header line for easier parsing. Because it’s just text and uses the same format that Fiddler uses for exports, it’s super easy to create Sessions by hand manually or under program control writing out to a simple text file. You can see what this format looks like in the Capture window figure above – the raw captured format is also what’s stored to disk and what WebSurge parses from. The only ‘custom’ part of these headers is that 1st line contains the full URL instead of the domain relative path and Host: header. The rest of each header are just plain standard HTTP headers with each individual URL isolated by a separator line. The format used here also uses what Fiddler produces for exports, so it’s easy to exchange or view data either in Fiddler or WebSurge. Urls can also be edited interactively so you can modify the headers easily as well: Again – it’s just plain HTTP headers so anything you can do with HTTP can be added here. Use it for single URL Testing Incidentally I’ve also found this form as an excellent way to test and replay individual URLs for simple non-load testing purposes. Because you can capture a single or many URLs and store them on disk, this also provides a nice HTTP playground where you can record URLs with their headers, and fire them one at a time or as a session and see results immediately. It’s actually an easy way for REST presentations and I find the simple UI flow actually easier than using Fiddler natively. Finally you can save one or more URLs as a session for later retrieval. I’m using this more and more for simple URL checks. Overriding Cookies and Domains Speaking of HTTP headers – you can also overwrite cookies used as part of the options. One thing that happens with modern Web applications is that you have session cookies in use for authorization. These cookies tend to expire at some point which would invalidate a test. Using the Options dialog you can actually override the cookie: which replaces the cookie for all requests with the cookie value specified here. You can capture a valid cookie from a manual HTTP request in your browser and then paste into the cookie field, to replace the existing Cookie with the new one that is now valid. Likewise you can easily replace the domain so if you captured urls on west-wind.com and now you want to test on localhost you can do that easily easily as well. You could even do something like capture on store.west-wind.com and then test on localhost/store which would also work. Running Load Tests Once you’ve created a Session you can specify the length of the test in seconds, and specify the number of simultaneous threads to run each session on. Sessions run through each of the URLs in the session sequentially by default. One option in the options list above is that you can also randomize the URLs so each thread runs requests in a different order. This avoids bunching up URLs initially when tests start as all threads run the same requests simultaneously which can sometimes skew the results of the first few minutes of a test. While sessions run some progress information is displayed: By default there’s a live view of requests displayed in a Console-like window. On the bottom of the window there’s a running total summary that displays where you’re at in the test, how many requests have been processed and what the requests per second count is currently for all requests. Note that for tests that run over a thousand requests a second it’s a good idea to turn off the console display. While the console display is nice to see that something is happening and also gives you slight idea what’s happening with actual requests, once a lot of requests are processed, this UI updating actually adds a lot of CPU overhead to the application which may cause the actual load generated to be reduced. If you are running a 1000 requests a second there’s not much to see anyway as requests roll by way too fast to see individual lines anyway. If you look on the options panel, there is a NoProgressEvents option that disables the console display. Note that the summary display is still updated approximately once a second so you can always tell that the test is still running. Test Results When the test is done you get a simple Results display: On the right you get an overall summary as well as breakdown by each URL in the session. Both success and failures are highlighted so it’s easy to see what’s breaking in your load test. The report can be printed or you can also open the HTML document in your default Web Browser for printing to PDF or saving the HTML document to disk. The list on the right shows you a partial list of the URLs that were fired so you can look in detail at the request and response data. The list can be filtered by success and failure requests. Each list is partial only (at the moment) and limited to a max of 1000 items in order to render reasonably quickly. Each item in the list can be clicked to see the full request and response data: This particularly useful for errors so you can quickly see and copy what request data was used and in the case of a GET request you can also just click the link to quickly jump to the page. For non-GET requests you can find the URL in the Session list, and use the context menu to Test the URL as configured including any HTTP content data to send. You get to see the full HTTP request and response as well as a link in the Request header to go visit the actual page. Not so useful for a POST as above, but definitely useful for GET requests. Finally you can also get a few charts. The most useful one is probably the Request per Second chart which can be accessed from the Charts menu or shortcut. Here’s what it looks like:   Results can also be exported to JSON, XML and HTML. Keep in mind that these files can get very large rather quickly though, so exports can end up taking a while to complete. Command Line Interface WebSurge runs with a small core load engine and this engine is plugged into the front end application I’ve shown so far. There’s also a command line interface available to run WebSurge from the Windows command prompt. Using the command line you can run tests for either an individual URL (similar to AB.exe for example) or a full Session file. By default when it runs WebSurgeCli shows progress every second showing total request count, failures and the requests per second for the entire test. A silent option can turn off this progress display and display only the results. The command line interface can be useful for build integration which allows checking for failures perhaps or hitting a specific requests per second count etc. It’s also nice to use this as quick and dirty URL test facility similar to the way you’d use Apache Bench (ab.exe). Unlike ab.exe though, WebSurgeCli supports SSL and makes it much easier to create multi-URL tests using either manual editing or the WebSurge UI. Current Status Currently West Wind WebSurge is still in Beta status. I’m still adding small new features and tweaking the UI in an attempt to make it as easy and self-explanatory as possible to run. Documentation for the UI and specialty features is also still a work in progress. I plan on open-sourcing this product, but it won’t be free. There’s a free version available that provides a limited number of threads and request URLs to run. A relatively low cost license  removes the thread and request limitations. Pricing info can be found on the Web site – there’s an introductory price which is $99 at the moment which I think is reasonable compared to most other for pay solutions out there that are exorbitant by comparison… The reason code is not available yet is – well, the UI portion of the app is a bit embarrassing in its current monolithic state. The UI started as a very simple interface originally that later got a lot more complex – yeah, that never happens, right? Unless there’s a lot of interest I don’t foresee re-writing the UI entirely (which would be ideal), but in the meantime at least some cleanup is required before I dare to publish it :-). The code will likely be released with version 1.0. I’m very interested in feedback. Do you think this could be useful to you and provide value over other tools you may or may not have used before? I hope so – it already has provided a ton of value for me and the work I do that made the development worthwhile at this point. You can leave a comment below, or for more extensive discussions you can post a message on the West Wind Message Board in the WebSurge section Microsoft MVPs and Insiders get a free License If you’re a Microsoft MVP or a Microsoft Insider you can get a full license for free. Send me a link to your current, official Microsoft profile and I’ll send you a not-for resale license. Send any messages to [email protected]. Resources For more info on WebSurge and to download it to try it out, use the following links. West Wind WebSurge Home Download West Wind WebSurge Getting Started with West Wind WebSurge Video© Rick Strahl, West Wind Technologies, 2005-2014Posted in ASP.NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Visual Studio 2010 SP1 Beta supports IIS Express

    - by DigiMortal
    Visual Studio 2010 SP1 Beta and ASP.NET MVC 3 RC2 were both announced today. I made a little test on one of my web applications to see how Visual Studio 2010 works with IIS Express. In this posting I will show you how to make your ASP.NET MVC 3 application work with IIS Express. Installing new stuff You can install IIS Express using Web Platform Installer. It is not part of WebMatrix anymore and you can just install IIS Express without WebMatrix. NB! You have to install IIS Express using Web Platform installer because IIS Express is not installed by SP1. After installing Visual Studio 2010 SP1 Beta on my machine (it took a long-long-long time to install) I installed also ASP.NET MVC 3 RC2. If you have Async CTP installed on your machine you have to uninstall it to get ASP.NET MVC 3 RC2 installed and run without problems. Screenshot on right shows what kinf of horrors my old laptop had to survive to get all new stuff installer. Setting IIS Express as server for web application Now, when you right-click on some web project you should see new menu item in context menu – Use IIS Express…. If you click on it you are asked for confirmation and if you say Yes then your web application is reconfigured to use IIS Express. After configuration you will see dialog box like this. And you are done. You can run your application now. Running web application When you run your application it is run on IIS Express. You can see IIS Express icon on taskbar and when you click it you can open IIS Express settings. If you closed your application in browser you can open it again from IIS Express icon. Modifying IIS Express settings for web application You can modify IIS Express settings for your application. Just open your project properties and move to Web tab. IIS and IIS Express are using same settings. The difference is if you make check to Use IIS Express checkbox or not. Switching back to Visual Studio Development Server If you don’t want or you can’t use IIS Express for some reason you can easily switch back to Visual Studio Development Server. Just right-click on your web application project and select Use Visual Studio Development Server from context menu. Conclusion IIS Express is more independent than full version of IIS and it can be also installed and run on machines where are very strict rules (some corporate and academic environments by example). IIS Express was previously part of WebMatrix package but now it is separate product and Visual Studio 2010 has very nice support for it thanks to SP1. You can easily make your web applications use IIS Express and if you want to switch back to development server it is also very easy.

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  • SQL Authority News – Download Microsoft SQL Server 2014 Feature Pack and Microsoft SQL Server Developer’s Edition

    - by Pinal Dave
    Yesterday I attended the SQL Server Community Launch in Bangalore and presented on Performing an effective Presentation. It was a fun presentation and people very well received it. No matter on what subject, I present, I always end up talking about SQL. Here are two of the questions I had received during the event. Q1) I want to install SQL Server on my development server, where can we get it for free or at an economical price (I do not have MSDN)? A1) If you are not going to use your server in a production environment, you can just get SQL Server Developer’s Edition and you can read more about it over here. Here is another favorite question which I keep on receiving it during the event. Q2) I already have SQL Server installed on my machine, what are different feature pack should I install and where can I get them from. A2) Just download and install Microsoft SQL Server 2014 Service Pack. Here is the link for downloading it. The Microsoft SQL Server 2014 Feature Pack is a collection of stand-alone packages which provide additional value for Microsoft SQL Server. It includes tool and components for Microsoft SQL Server 2014 and add-on providers for Microsoft SQL Server 2014. Here is the list of component this product contains: Microsoft SQL Server Backup to Windows Azure Tool Microsoft SQL Server Cloud Adapter Microsoft Kerberos Configuration Manager for Microsoft SQL Server Microsoft SQL Server 2014 Semantic Language Statistics Microsoft SQL Server Data-Tier Application Framework Microsoft SQL Server 2014 Transact-SQL Language Service Microsoft Windows PowerShell Extensions for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Shared Management Objects Microsoft Command Line Utilities 11 for Microsoft SQL Server Microsoft ODBC Driver 11 for Microsoft SQL Server – Windows Microsoft JDBC Driver 4.0 for Microsoft SQL Server Microsoft Drivers 3.0 for PHP for Microsoft SQL Server Microsoft SQL Server 2014 Transact-SQL ScriptDom Microsoft SQL Server 2014 Transact-SQL Compiler Service Microsoft System CLR Types for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Remote Blob Store SQL RBS codeplex samples page SQL Server Remote Blob Store blogs Microsoft SQL Server Service Broker External Activator for Microsoft SQL Server 2014 Microsoft OData Source for Microsoft SQL Server 2014 Microsoft Balanced Data Distributor for Microsoft SQL Server 2014 Microsoft Change Data Capture Designer and Service for Oracle by Attunity for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Master Data Service Add-in for Microsoft Excel Microsoft SQL Server StreamInsight Microsoft Connector for SAP BW for Microsoft SQL Server 2014 Microsoft SQL Server Migration Assistant Microsoft SQL Server 2014 Upgrade Advisor Microsoft OLEDB Provider for DB2 v5.0 for Microsoft SQL Server 2014 Microsoft SQL Server 2014 PowerPivot for Microsoft SharePoint 2013 Microsoft SQL Server 2014 ADOMD.NET Microsoft Analysis Services OLE DB Provider for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Analysis Management Objects Microsoft SQL Server Report Builder for Microsoft SQL Server 2014 Microsoft SQL Server 2014 Reporting Services Add-in for Microsoft SharePoint Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL

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  • Ajax Control Toolkit and Superexpert

    - by Stephen Walther
    Microsoft has asked my company, Superexpert Consulting, to take ownership of the development and maintenance of the Ajax Control Toolkit moving forward. In this blog entry, I discuss our strategy for improving the Ajax Control Toolkit. Why the Ajax Control Toolkit? The Ajax Control Toolkit is one of the most popular projects on CodePlex. In fact, some have argued that it is among the most successful open-source projects of all time. It consistently receives over 3,500 downloads a day (not weekends -- workdays). A mind-boggling number of developers use the Ajax Control Toolkit in their ASP.NET Web Forms applications. Why does the Ajax Control Toolkit continue to be such a popular project? The Ajax Control Toolkit fills a strong need in the ASP.NET Web Forms world. The Toolkit enables Web Forms developers to build richly interactive JavaScript applications without writing any JavaScript. For example, by taking advantage of the Ajax Control Toolkit, a Web Forms developer can add modal dialogs, popup calendars, and client tabs to a web application simply by dragging web controls onto a page. The Ajax Control Toolkit is not for everyone. If you are comfortable writing JavaScript then I recommend that you investigate using jQuery plugins instead of the Ajax Control Toolkit. However, if you are a Web Forms developer and you don’t want to get your hands dirty writing JavaScript, then the Ajax Control Toolkit is a great solution. The Ajax Control Toolkit is Vast The Ajax Control Toolkit consists of 40 controls. That’s a lot of controls (For the sake of comparison, jQuery UI consists of only 8 controls – those slackers J). Furthermore, developers expect the Ajax Control Toolkit to work on browsers both old and new. For example, people expect the Ajax Control Toolkit to work with Internet Explorer 6 and Internet Explorer 9 and every version of Internet Explorer in between. People also expect the Ajax Control Toolkit to work on the latest versions of Mozilla Firefox, Apple Safari, and Google Chrome. And, people expect the Ajax Control Toolkit to work with different operating systems. Yikes, that is a lot of combinations. The biggest challenge which my company faces in supporting the Ajax Control Toolkit is ensuring that the Ajax Control Toolkit works across all of these different browsers and operating systems. Testing, Testing, Testing Because we wanted to ensure that we could easily test the Ajax Control Toolkit with different browsers, the very first thing that we did was to set up a dedicated testing server. The dedicated server -- named Schizo -- hosts 4 virtual machines so that we can run Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, and Internet Explorer 9 at the same time (We also use the virtual machines to host the latest versions of Firefox, Chrome, Opera, and Safari). The five developers on our team (plus me) can each publish to a separate FTP website on the testing server. That way, we can quickly test how changes to the Ajax Control Toolkit affect different browsers. QUnit Tests for the Ajax Control Toolkit Introducing regressions – introducing new bugs when trying to fix existing bugs – is the concern which prevents me from sleeping well at night. There are so many people using the Ajax Control Toolkit in so many unique scenarios, that it is difficult to make improvements to the Ajax Control Toolkit without introducing regressions. In order to avoid regressions, we decided early on that it was extremely important to build good test coverage for the 40 controls in the Ajax Control Toolkit. We’ve been focusing a lot of energy on building automated JavaScript unit tests which we can use to help us discover regressions. We decided to write the unit tests with the QUnit test framework. We picked QUnit because it is quickly becoming the standard unit testing framework in the JavaScript world. For example, it is the unit testing framework used by the jQuery team, the jQuery UI team, and many jQuery UI plugin developers. We had to make several enhancements to the QUnit framework in order to test the Ajax Control Toolkit. For example, QUnit does not support tests which include postbacks. We modified the QUnit framework so that it works with IFrames so we could perform postbacks in our automated tests. At this point, we have written hundreds of QUnit tests. For example, we have written 135 QUnit tests for the Accordion control. The QUnit tests are included with the Ajax Control Toolkit source code in a project named AjaxControlToolkit.Tests. You can run all of the QUnit tests contained in the project by opening the Default.aspx page. Automating the QUnit Tests across Multiple Browsers Automated tests are useless if no one ever runs them. In order for the QUnit tests to be useful, we needed an easy way to run the tests automatically against a matrix of browsers. We wanted to run the unit tests against Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, Internet Explorer 9, Firefox, Chrome, and Safari automatically. Expecting a developer to run QUnit tests against every browser after every check-in is just too much to expect. It takes 20 seconds to run the Accordion QUnit tests. We are testing against 8 browsers. That would require the developer to open 8 browsers and wait for the results after each change in code. Too much work. Therefore, we built a JavaScript Test Server. Our JavaScript Test Server project was inspired by John Resig’s TestSwarm project. The JavaScript Test Server runs our QUnit tests in a swarm of browsers (running on different operating systems) automatically. Here’s how the JavaScript Test Server works: 1. We created an ASP.NET page named RunTest.aspx that constantly polls the JavaScript Test Server for a new set of QUnit tests to run. After the RunTest.aspx page runs the QUnit tests, the RunTest.aspx records the test results back to the JavaScript Test Server. 2. We opened the RunTest.aspx page on instances of Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, Internet Explorer 9, FireFox, Chrome, Opera, Google, and Safari. Now that we have the JavaScript Test Server setup, we can run all of our QUnit tests against all of the browsers which we need to support with a single click of a button. A New Release of the Ajax Control Toolkit Each Month The Ajax Control Toolkit Issue Tracker contains over one thousand five hundred open issues and feature requests. So we have plenty of work on our plates J At CodePlex, anyone can vote for an issue to be fixed. Originally, we planned to fix issues in order of their votes. However, we quickly discovered that this approach was inefficient. Constantly switching back and forth between different controls was too time-consuming. It takes time to re-familiarize yourself with a control. Instead, we decided to focus on two or three controls each month and really focus on fixing the issues with those controls. This way, we can fix sets of related issues and avoid the randomization caused by context switching. Our team works in monthly sprints. We plan to do another release of the Ajax Control Toolkit each and every month. So far, we have competed one release of the Ajax Control Toolkit which was released on April 1, 2011. We plan to release a new version in early May. Conclusion Fortunately, I work with a team of smart developers. We currently have 5 developers working on the Ajax Control Toolkit (not full-time, they are also building two very cool ASP.NET MVC applications). All the developers who work on our team are required to have strong JavaScript, jQuery, and ASP.NET MVC skills. In the interest of being as transparent as possible about our work on the Ajax Control Toolkit, I plan to blog frequently about our team’s ongoing work. In my next blog entry, I plan to write about the two Ajax Control Toolkit controls which are the focus of our work for next release.

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  • C# 4: The Curious ConcurrentDictionary

    - by James Michael Hare
    In my previous post (here) I did a comparison of the new ConcurrentQueue versus the old standard of a System.Collections.Generic Queue with simple locking.  The results were exactly what I would have hoped, that the ConcurrentQueue was faster with multi-threading for most all situations.  In addition, concurrent collections have the added benefit that you can enumerate them even if they're being modified. So I set out to see what the improvements would be for the ConcurrentDictionary, would it have the same performance benefits as the ConcurrentQueue did?  Well, after running some tests and multiple tweaks and tunes, I have good and bad news. But first, let's look at the tests.  Obviously there's many things we can do with a dictionary.  One of the most notable uses, of course, in a multi-threaded environment is for a small, local in-memory cache.  So I set about to do a very simple simulation of a cache where I would create a test class that I'll just call an Accessor.  This accessor will attempt to look up a key in the dictionary, and if the key exists, it stops (i.e. a cache "hit").  However, if the lookup fails, it will then try to add the key and value to the dictionary (i.e. a cache "miss").  So here's the Accessor that will run the tests: 1: internal class Accessor 2: { 3: public int Hits { get; set; } 4: public int Misses { get; set; } 5: public Func<int, string> GetDelegate { get; set; } 6: public Action<int, string> AddDelegate { get; set; } 7: public int Iterations { get; set; } 8: public int MaxRange { get; set; } 9: public int Seed { get; set; } 10:  11: public void Access() 12: { 13: var randomGenerator = new Random(Seed); 14:  15: for (int i=0; i<Iterations; i++) 16: { 17: // give a wide spread so will have some duplicates and some unique 18: var target = randomGenerator.Next(1, MaxRange); 19:  20: // attempt to grab the item from the cache 21: var result = GetDelegate(target); 22:  23: // if the item doesn't exist, add it 24: if(result == null) 25: { 26: AddDelegate(target, target.ToString()); 27: Misses++; 28: } 29: else 30: { 31: Hits++; 32: } 33: } 34: } 35: } Note that so I could test different implementations, I defined a GetDelegate and AddDelegate that will call the appropriate dictionary methods to add or retrieve items in the cache using various techniques. So let's examine the three techniques I decided to test: Dictionary with mutex - Just your standard generic Dictionary with a simple lock construct on an internal object. Dictionary with ReaderWriterLockSlim - Same Dictionary, but now using a lock designed to let multiple readers access simultaneously and then locked when a writer needs access. ConcurrentDictionary - The new ConcurrentDictionary from System.Collections.Concurrent that is supposed to be optimized to allow multiple threads to access safely. So the approach to each of these is also fairly straight-forward.  Let's look at the GetDelegate and AddDelegate implementations for the Dictionary with mutex lock: 1: var addDelegate = (key,val) => 2: { 3: lock (_mutex) 4: { 5: _dictionary[key] = val; 6: } 7: }; 8: var getDelegate = (key) => 9: { 10: lock (_mutex) 11: { 12: string val; 13: return _dictionary.TryGetValue(key, out val) ? val : null; 14: } 15: }; Nothing new or fancy here, just your basic lock on a private object and then query/insert into the Dictionary. Now, for the Dictionary with ReadWriteLockSlim it's a little more complex: 1: var addDelegate = (key,val) => 2: { 3: _readerWriterLock.EnterWriteLock(); 4: _dictionary[key] = val; 5: _readerWriterLock.ExitWriteLock(); 6: }; 7: var getDelegate = (key) => 8: { 9: string val; 10: _readerWriterLock.EnterReadLock(); 11: if(!_dictionary.TryGetValue(key, out val)) 12: { 13: val = null; 14: } 15: _readerWriterLock.ExitReadLock(); 16: return val; 17: }; And finally, the ConcurrentDictionary, which since it does all it's own concurrency control, is remarkably elegant and simple: 1: var addDelegate = (key,val) => 2: { 3: _concurrentDictionary[key] = val; 4: }; 5: var getDelegate = (key) => 6: { 7: string s; 8: return _concurrentDictionary.TryGetValue(key, out s) ? s : null; 9: };                    Then, I set up a test harness that would simply ask the user for the number of concurrent Accessors to attempt to Access the cache (as specified in Accessor.Access() above) and then let them fly and see how long it took them all to complete.  Each of these tests was run with 10,000,000 cache accesses divided among the available Accessor instances.  All times are in milliseconds. 1: Dictionary with Mutex Locking 2: --------------------------------------------------- 3: Accessors Mostly Misses Mostly Hits 4: 1 7916 3285 5: 10 8293 3481 6: 100 8799 3532 7: 1000 8815 3584 8:  9:  10: Dictionary with ReaderWriterLockSlim Locking 11: --------------------------------------------------- 12: Accessors Mostly Misses Mostly Hits 13: 1 8445 3624 14: 10 11002 4119 15: 100 11076 3992 16: 1000 14794 4861 17:  18:  19: Concurrent Dictionary 20: --------------------------------------------------- 21: Accessors Mostly Misses Mostly Hits 22: 1 17443 3726 23: 10 14181 1897 24: 100 15141 1994 25: 1000 17209 2128 The first test I did across the board is the Mostly Misses category.  The mostly misses (more adds because data requested was not in the dictionary) shows an interesting trend.  In both cases the Dictionary with the simple mutex lock is much faster, and the ConcurrentDictionary is the slowest solution.  But this got me thinking, and a little research seemed to confirm it, maybe the ConcurrentDictionary is more optimized to concurrent "gets" than "adds".  So since the ratio of misses to hits were 2 to 1, I decided to reverse that and see the results. So I tweaked the data so that the number of keys were much smaller than the number of iterations to give me about a 2 to 1 ration of hits to misses (twice as likely to already find the item in the cache than to need to add it).  And yes, indeed here we see that the ConcurrentDictionary is indeed faster than the standard Dictionary here.  I have a strong feeling that as the ration of hits-to-misses gets higher and higher these number gets even better as well.  This makes sense since the ConcurrentDictionary is read-optimized. Also note that I tried the tests with capacity and concurrency hints on the ConcurrentDictionary but saw very little improvement, I think this is largely because on the 10,000,000 hit test it quickly ramped up to the correct capacity and concurrency and thus the impact was limited to the first few milliseconds of the run. So what does this tell us?  Well, as in all things, ConcurrentDictionary is not a panacea.  It won't solve all your woes and it shouldn't be the only Dictionary you ever use.  So when should we use each? Use System.Collections.Generic.Dictionary when: You need a single-threaded Dictionary (no locking needed). You need a multi-threaded Dictionary that is loaded only once at creation and never modified (no locking needed). You need a multi-threaded Dictionary to store items where writes are far more prevalent than reads (locking needed). And use System.Collections.Concurrent.ConcurrentDictionary when: You need a multi-threaded Dictionary where the writes are far more prevalent than reads. You need to be able to iterate over the collection without locking it even if its being modified. Both Dictionaries have their strong suits, I have a feeling this is just one where you need to know from design what you hope to use it for and make your decision based on that criteria.

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