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  • bulleted lists for plain-text documents in Vim

    - by AnC
    While Vim supports automatic indenting in lists, the default setting only covers ordered lists, starting with digits: 1. Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim 2. veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. I have not been able to figure out how to extend this to unordered, bulleted lists: * Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim * veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Changing the formatlistpat RegEx did not lead to the desired results (indeed, it even broke ordered lists). Any help would be appreciated!

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  • Using an actor model versus a producer-consumer model?

    - by hewhocutsdown
    I'm doing some early-stage research towards architecting a new software application. Concurrency and multithreading will likely play a significant part, so I've been reading up on the various topics. The producer-consumer model, at least how it is expressed in Java, has some surface similarities but appears to be deeply dissimilar to the actor model in use with languages such as Erlang and Scala. I'm having trouble finding any good comparative data, or specific reasons to use or avoid the one or the other. Is the actor model even possible with Java or C#, or do you have do use one of the languages built for the purpose? Is there a third way?

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  • SPARC at 25: Past, Present and Future

    - by kgee
    Join us online to celebrate a quarter-century of innovation. Watch Scott McNealy, Bill Joy, and Andy Bechtolsheim along with other significant SPARC contributors discuss the challenges and rewards of consistently redefining the limits of enterprise IT. Hear Mark Hurd and John Fowler talk about the aggressive plans for SPARC’s future. All of this was recently captured in video at the SPARC anniversary event held at the Computer History Museum in Mountain View, California. In addition to getting unique insights from the people behind 25 years of SPARC technology, you can access exclusive content and resources, read case studies and e-Books, view webcasts and infographics, and more. Be sure to take some time to rediscover why and how SPARC was developed, the considerable impact it had on the entire IT industry, and the continuing innovations coming in the future.http://www.oracle.com/go/?&Src=7618691&Act=721&pcode=WWMK12044691MPP051

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  • Implementing a bit shift using AND, NOT, ADD [closed]

    - by fdart17
    I'm implementing a 16-bit left bit shift by r bits, and I only have access to AND, NOT and ADD. There are 3 condition codes, negative, zero and positive, which are set when you use any of these operations. How I went about it was : (1) And the number with 1000 0000 0000 0000 to set condition codes to positive if the most significant bit is 1. (2) Add the number with itself. This shifts bits one to the left. (3) If the MSB was 1, add 1 to the result. (4) Loop threw (1)-(3) r times. I'm wondering if anyone has any hints to some more efficient methods? Thanks!

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  • News Flash: Hong Kong Housing Society Improves Governance Control, Reduces Costs by 25%, Speeds up Approval by 30%

    - by Ruma Sanyal
    “We selected Oracle Fusion Middleware for its superior local support, higher performance, availability, reliability, and flexible enterprise architecture to cost-effectively integrate with existing Oracle applications", said Mr. C.W. Miao, Head of Information Technology, Hong Kong Housing Society in a press release today. To address the challenge of frequent downtime during peak periods and increasing cost in maintaining its legacy systems, Hong Kong Housing Society replaced its legacy systems with Oracle's WebLogic Suite, BPM Suite, and the ADF Framework. The Fusion Middleware solutions provide Hong Kong Housing Society with a flexible, reliable and cost-effective enterprise architecture that enables integration with existing Oracle applications including JD Edwards EnterpriseOne and PeopleSoft. The cost savings and performance results clearly demonstrate significant benefits. Read the PR for complete details.

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  • What sort of phone numbers are allowed as the WHOIS contact?

    - by billpg
    I'm getting a non-trivial amount of scam phone calls to the phone number contact listed in WHOIS. Could I change it to a premium rate line? If the scammers want to talk to me so much, make them pay for the privilege! Seriously though, are there any restrictions on the type of phone number I can give as my WHOIS contact? Notwithstanding that it is a phone number which can be used to contact the domain holder. In the UK, cell phones are more expensive for the caller to call than land-lines, so I suspect a significant number of people are already listing a "premium rate" phone number.

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  • Use Your Android Phone to Comparison Shop: 4 Scanner Apps Reviewed

    - by Jason Fitzpatrick
    A smart phone in your pocket is great for on the go news, web browsing, and—of course—mobile gaming. It’s also fantastic for comparison shopping. Today we take a look at four Android scanners and price comparison engines. It’s quite a neat time to be a consumer. Historically if you wanted to do serious price comparisons you had to haul yourself around town, gather flyers from the newspapers, and otherwise invest way too much energy into potential savings that might not even break into double digits. Now you can comparison shop with an ease that borders on magic: by simply pulling out your smart phone and scanning the barcode or typing in the name of the item you wish to compare. Today we’re taking a look at some of the more popular and powerful barcode scanners and price comparison engines available for the Android platform. Before we get to that, a word on our methodology. To test the barcode scanners and the resulting search results we wandered around and rounded up some relatively random items from around the How-To Geek offices. This included a children’s graphic novel, a Wii game, a board game, a pack of razors, a box of tea, and a bottle of nail polish. It’s a decent spread of consumer items that covers several genres. For each application we scanned all the items, looked for the best price at the time, and noted any other relevant benefits of using one scanner over another. It’s worth noting that our primary focus was on the speed and ease of use. You may find that certain scanners have specific features that best suit your needs. What we focused on was how fast you could scan, compare prices, and purchase items if you desired. Since all the scanners are free-as-in-beer, feel free to download them all and run your own tests to confirm our conclusions. Use Your Android Phone to Comparison Shop: 4 Scanner Apps Reviewed How to Run Android Apps on Your Desktop the Easy Way HTG Explains: Do You Really Need to Defrag Your PC?

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  • Is there any advantage in using DX10/11 for a 2D game?

    - by David Gouveia
    I'm not entirely familiar with the feature set introduced by DX10/11 class hardware. I'm vaguely familiar with the new stages added to the programmable graphics pipeline, such as the geometry shader, the compute shader, and the new tesselation stages. I don't see how any of these make much of a difference for a 2D game though. Is there any compelling reason to make the switch to DX10/11 (or the OpenGL equivalents) for a 2D game, or would it be wiser to stick with DX9 considering that that a significant share of the market still runs on older technologies (e.g. the February 2012 Steam surveys lists around 17% of users as still using Windows XP)?

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  • What are the downsides of leaving automation tags in production code?

    - by joshin4colours
    I've been setting up debug tags for automated testing of a GWT-based web application. This involves turning on custom debug id tags/attributes for elements in the source of the app. It's a non-trivial task, particularly for larger, more complex web applications. Recently there's been some discussion of whether enabling such debug ids is a good idea to do across the board. Currently the debug ids are only turned on in development and testing servers, not in production. There have been points raised that enabling debug ids does cause performance to take a hit, and that debug ids in production may lead to security issues. What are benefits of doing this? Are there any significant risks for turning on debug tags in production code?

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  • How is the iOS support in UDK compared to Unity?

    - by Joe
    I have some significant experience in Unity for web clients, but I'm skeptical about the 3K$ price tag to create/deploy iOS games. I noticed UDK now supports iOS, and appears to have "free" version control- and it's only 100$ from what I can tell. My primary question is: Does UDK make iOS development and deployment easy, or do you have to jump through a couple of hoops to make it work? A few side questions not worth another post: How hard is the transition from Unity to UDK? Is UnrealScript easy to pick up from a C/C# background? Does the UDK have good documentation compared to Unity?

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  • PanelGridLayout - A Layout Revolution

    - by Duncan Mills
    With the most recent 11.1.2 patchset (11.1.2.3) there has been a lot of excitement around ADF Essentials (and rightly so), however, in all the fuss I didn't want an even more significant change to get missed - yes you read that correctly, a more significant change! I'm talking about the new panelGridLayout component, I can confidently say that this one of the most revolutionary components that we've introduced in 11g, even though it sounds rather boring. To be totally accurate, panelGrid was introduced in 11.1.2.2 but without any presence in the component palette or other design time support, so it was largely missed unless you read the release notes. However in this latest patchset it's finally front and center. Its time to explore - we (really) need to talk about layout.  Let's face it,with ADF Faces rich client, layout is a rather arcane pursuit, once you are a layout master, all bow before you, but it's more of an art than a science, and it is often, in fact, way too difficult to achieve what should (apparently) be a pretty simple. Here's a great example, it's a homework assignment I set for folks I'm teaching this stuff to:  The requirements for this layout are: The header is 80px high, the footer is 30px. These are both fixed.  The first section of the header containing the logo is 180px wide The logo is centered within the top left hand corner of the header  The title text is start aligned in the center zone of the header and will wrap if the browser window is narrowed. It should be aligned in the center of the vertical space  The about link is anchored to the right hand side of the browser with a 20px gap and again is center aligned vertically. It will move as the browser window is reduced in width. The footer has a right aligned copyright statement, again middle aligned within a 30px high footer region and with a 20px buffer to the right hand edge. It will move as the browser window is reduced in width. All remaining space is given to a central zone, which, in this case contains a panelSplitter. Expect that at some point in time you'll need a separate messages line in the center of the footer.  In the homework assigment I set I also stipulate that no inlineStyles can be used to control alignment or margins and no use of other taglibs (e.g. JSF HTML or Trinidad HTML). So, if we take this purist approach, that basic page layout (in my stock solution) requires 3 panelStretchLayouts, 5 panelGroupLayouts and 4 spacers - not including the spacer I use for the logo and the contents of the central zone splitter - phew! The point is that even a seemingly simple layout needs a bit of thinking about, particulatly when you consider strechting and browser re-size behavior. In fact, this little sample actually teaches you much of what you need to know to become vaguely competant at layouts in the framework. The underlying result of "the way things are" is that most of us reach for panelStretchLayout before even finishing the first sip of coffee as we embark on a new page design. In fact most pages you will see in any moderately complex ADF page will basically be nested panelStretchLayouts and panelGroupLayouts, sometimes many, many levels deep. So this is a problem, we've known this for some time and now we have a good solution. (I should point out that the oft-used Trinidad trh tags are not a particularly good solution as you're tie-ing yourself to an HTML table based layout in that case with a host of attendent issues in resize and bi-di behavior, but I digress.) So, tadaaa, I give to you panelGridLayout. PanelGrid, as the name suggests takes a grid like (dare I say slightly gridbag-like) approach to layout, dividing your layout into rows and colums with margins, sizing, stretch behaviour, colspans and rowspans all rolled in, all without the use of inlineStyle. As such, it provides for a much more powerful and consise way of defining a layout such as the one above that is actually simpler and much more logical to design. The basic building blocks are the panelGridLayout itself, gridRow and gridCell. Your content sits inside the cells inside the rows, all helpfully allowing both streching, valign and halign definitions without the need to nest further panelGroupLayouts. So much simpler!  If I break down the homework example above my nested comglomorate of 12 containers and spacers can be condensed down into a single panelGrid with 3 rows and 5 cell definitions (39 lines of source reduced to 24 in the case of the sample). What's more, the actual runtime representation in the browser DOM is much, much simpler, and clean, with basically one DIV per cell (Note that just because the panelGridLayout semantics looks like an HTML table does not mean that it's rendered that way!) . Another hidden benefit is the runtime cost. Because we can use a single layout to achieve much more complex geometries the client side layout code inside the browser is having to work a lot less. This will be a real benefit if your application needs to run on lower powered clients such as netbooks or tablets. So, it's time, if you're on 11.1.2.2 or above, to smile warmly at your panelStretchLayouts, wrap the blanket around it's knees and wheel it off to the Sunset Retirement Home for a well deserved rest. There's a new kid on the block and it wants to be your friend. 

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  • May the file size returned by stat be compromised?

    - by codeholic
    I want to make sure that nobody changed a file. In order to accomplish that, I want not only to check MD5 sum of the file, but also check its size, since as far as I understand this additional simple check can sophisticate falsification by several digits. May I trust the size that stat returns? I don't mean if changes were made to stat itself. I don't go that deep. But, for instance, may one compromise the file size that stat returns by hacking the directory file? Or by similar means, that do not require superuser privileges? It's Linux.

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  • Upgrading visual studio with Crystal Reports

    - by jkrebsbach
    In the process up updating an app from Visual Studio 2003 to VS 2008.  It happens to have a couple dozen crystal reports that it executes regarly. Upgraded visual studio to 2008, and when attempting to generate the reports an exception was thrown. A significant portion of the rendering engine for Crystal Reports is not coming from Crystal, it's coming from Visual Studio and those methods and properties have changed over the years.  I needed to upgrade the report generating methods from the VS 2003 way of doing things to the VS 2008 way for the report to generate successfully. Not only that, but this means that while we were previously rendering with Crystal 9 in VS 2003, Visual Studio 2008 will render per Crystal 10, which treats things like column widths in Excel different (by default, at least) so now we have to go through all of our reports and compare outputs for Crystal just to upgrade the Visual Studio environment that I foolishly believed would  not be affected.

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  • Dec. 6 Webcast: See the New UI for JD Edwards

    - by Theresa Hickman
    When: Dec. 6, 2011 Time: 8:00am PST What: Live webcast and demo Tune into this live webcast to see the just completed new JD Edwards EnterpriseOne User Interface. This is one of the most significant releases with a massive number of feature innovations for users and system administrators. We are looking forward to demonstrating the new User Interface and Tools. The following panel of experts will be available to answer all your questions: Lyle Ekdahl – Oracle Group Vice President Gary Grieshaber – Oracle Strategy Senior Director Brian Stanz – Oracle Development Senior Director Click here to register. Note: You must pre-register for this event.

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  • Does anybody know what happens to money spent in the Ubuntu One Music Store?

    - by Dave
    I remember reading on the Canonical website around the launch of the Ubuntu One Music store that after revenue was divided between Canonical, 7 digital and the artists involved that all profit or a significant percentage would be donated to a charity. This information has either disappeared from their website or my detective skills have failed me once more. Does anybody happen to understand the break down of revenue generated by the Ubuntu One Music Store or even know where to find this information. Also it would be useful to know which charity benefits from this. (Not that that would impact upon my purchases or send me running to iTunes. ;) Promise)

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  • Maximum Length Of IP Address: 15 (IPv4) & 39(IPv6)

    - by Gopinath
    Problem You are designing a database table for a web application that requires to store IP address of users who visits the site. The IP address is required to be stored a character data in the table. To define size of the character column you need to know maximum length of IP address. So, what is the maximum length of an IP address? Solution The IPv4 version of IP address is in the following format 255.255.255.255 To store IPv4 address we require 15 characters. The IPv6 version of IP address is grouped into sets of 4 hex digits separated by colons, like the below 2001:0db8:85a3:0000:0000:8a2e:0370:7334 To store IPv6 address you require a 39 characters long column. Conclusion As IPv4 and IPv6 are the commonly use protocols, you better define a column with 39 characters length so that both the format address are saved in to the table without any issues. This article titled,Maximum Length Of IP Address: 15 (IPv4) & 39(IPv6), was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • Finding it Hard to Deliver Right Customer Experience: Think BPM!

    - by Ajay Khanna
    Our relationship with our customers is not a just a single interaction and we should not treat it like one. A customer’s relationship with a vendor is like a journey which starts way before customer makes a purchase and lasts long after that. The journey may start with customer researching a product that may lead to the eventual purchase and may continue with support or service needs for the product. A typical customer journey can be represented as shown below: As you may notice, customers tend to use multiple channels to interact with a company throughout their journey.  They also expect that they should get consistent experience, no matter what interaction channel they may choose. Customers do not like to repeat the information they have already provided and expect companies to remember their preferences, and offer them relevant products and services. If the company fails to meet this expectation, customers not only will abandon the purchase and go to the competitor but may also influence others’ purchase decision. Gone are the days when word of mouth was the only medium, and the customer could influence “Six” others. This is the age of social media and customer’s good or bad experience, especially bad get highly amplified and may influence hundreds of others. Challenges that face B2C companies today include: Delivering consistent experience: The reason that delivering consistent experience is challenging is due to fragmented data, disjointed systems and siloed multichannel interactions. Customers tend to get different service quality if they use web vs. phone vs. store. They get different responses from different service agents or get inconsistent answers if they call sales vs. service group in the company. Such inconsistent experiences result in lower customer satisfaction or NPS (net promoter score) numbers. Increasing Revenue: To stay competitive companies frequently introduce new products and services. Delay in launching such offerings has a significant impact on revenue realization. In addition to new product revenue, there are multiple opportunities to up-sell and cross-sell that impact bottom line. If companies are not able to identify such opportunities, bring a product to market quickly, or not offer the right product to the right customer at the right time, significant loss of revenue may occur. Ensuring Compliance: Companies must be compliant to ever changing regulations, these could be about Know Your Customer (KYC), Export/Import regulations, or taxation policies. In addition to government agencies, companies also need to comply with the SLA that they have committed to their customers. Lapse in meeting any of these requirements may lead to serious fines, penalties and loss in business. Companies have to make sure that they are in compliance will all such regulations and SLA commitments, at any given time. With the advent of social networks and mobile technology, companies not only need to focus on process efficiency but also on customer engagement. Improving engagement means delivering the customer experience as the customer is expecting and interacting with the customer at right time using right channel. Customers expect to be able to contact you via any channel of their choice (web, email, chat, mobile, social media), purchase via any viable channel (web, phone, store, mobile). Customers expect companies to understand their particular needs and remember their preferences on repeated visits. To deliver such an integrated, consistent, and contextual experience, power of BPM in must. Your company may be organized in departments like Marketing, Sales, Service. You may hold prospect data in SFA, order information in ERP, customer issues in CRM. However, the experience delivered to the customer must not be constrained by your system legacy. BPM helps in designing the right experience for the right customer and integrates all the underlining channels, systems, applications to make sure right information will be delivered to the right knowledge worker or to the customer every single time.     Orchestrating information across all systems (MDM, CRM, ERP), departments (commerce, merchandising, marketing service) and channels (Email, phone, web, social)  is the key, and that’s what BPM delivers. In addition to orchestrating systems and channels for consistency, BPM also provides an ability for analysis and decision management. By using data from historical transactions, social media and from other systems, users can determine the customer preferences, customer value, and churn propensity. This information, in the context, is then used while making a decision at a process step. Working with real-time decision management system can also suggest right up-sell or cross-sell offers, discounts or next-best-action steps for a particular customer. Timely action on customer issues or request is also a key tenet of a good customer experience. BPM’s complex event processing capabilities help companies to take proactive actions before issues get escalated. BPM system can be designed to listen to a certain event patters then deduce from those customer situations (credit card stolen, baggage lost, change of address) and do a triage before situation goes out of control. If such a situation arises you can send alerts to right people or immediately invoke corrective actions. Last but not least one of BPM’s key values is to drive continuous improvement. Learning about customers past experiences, interactions and social conversations, provide valuable insight. Such insight can be used to improve products, customer facing processes, and customer experience. You may take these insights as an input to design better more efficient and customer friendly sales, contact center or self-service processes. If customer experience is important for your business, make sure you have incorporated BPM as a part of your strategy to design, orchestrate and improve your customer facing processes.

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  • How to promote travel blog? [closed]

    - by Tschareck
    Possible Duplicate: What are the best ways to increase your site's position in Google? How can I increase the traffic to my site? I know this question might seem a little off topic, but blogging may become important part of travel. Nowadays, in time of Facebook, Twitter and similar services, keeping a travel blog may seem a little archaic. It's not 2005 anymore. But a lot of my travel colleagues update their blogs and have significant number of readers. I also tried to keep my blog when I travel. However it seems that the only reader is my mum ;) What is your advice on promoting a travel blog?

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  • What are the most common stumbling blocks when it comes to learning programming, in order of difficulty?

    - by blueberryfields
    I seem to remember that linked lists, recursion, pointers, and memory management are all good examples of stumbling blocks - places where the aspiring programmer typically ends up spending significant time trying to understand a concept before moving on and improving, and many end up giving up and not improving. I'm looking for a complete/comprehensive list of these types of stumbling blocks, in rough estimated order of difficulty to learn, with the goal of making sure that an educational program for programmers is structured to properly guide students through them Is this information available somewhere? Ideally, the difficulty to learn will be measured in some sort of objective manner (ie, % of students which consistently fail to learn the concept) What sources are most appropriate for obtaining this information?

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  • On-demand Webcast: Java in the Smart Grid

    - by Jacob Lehrbaum
    The Smart Grid is one of the most significant evolutions of our utility infrastructure in recent history. This innovative grid will soon revolutionize how utilities manage and control the energy in our homes--helping utilities reduce energy usage during peak hours, improve overall energy efficiency, and lower your energy bills. If you'd like to learn more about the Smart Grid and the role that Java is poised to play in this important initiative you can check out our on-demand webcast. We'll show you how Java solutions--including Java ME and Java SE for Embedded --can help build devices and infrastructure that take advantage of this new market. As the world's most popular developer language, Java enables you to work with a wide range of developers and provides access to tools and resources to build smarter devices, faster and more affordably.

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  • Add References with Search

    - by Daniel Cazzulino
    If you have been using VS2010 for any significant amount of time, you surely came across the awkward, slow and hard to use Add Reference dialog. Despite some (apparent) improvements over the VS2008 behavior, in its current form it's even LESS usable than before. A brief non-exhaustive summary of the typical grief with this dialog is: Scrolling a list of *hundreds* of entries? (300+ typically) No partial matching when typing: yes, you can type in the list to get to the desired entry, but the matching is performed in an exact manner, from the beginning of the assembly name. So, to get to the (say) "Microsoft.VisualStudio.Settings" assembly, you actually have to type the first two segments in their entirety before starting to type "Settings"....Read full article

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  • GPU On-the-fly encoding of video through Logitech HD Webcam C510

    - by Ashfame
    Originally asked here but I edited that to move this question as a different one on suggestion by a fellow member. I read that I should have a Core2Duo 2.2Ghz for 720p but I have a 2.0Ghz one, would it be possible for me to first record it and then encode it after recording if my processor really start giving issue when doing on-the-fly encoding? I also have a ATI HD 4850 512MB card, if it can help in encoding on-the-fly or is there a chance that my graphics card alone can handle it and those specs were just for a system without a graphics card? I believe so. Also, I got no worries in dealing with console, if I have to do some of the things above in terminal. Other possible significant details: I have a dual screen setup 29" (1360X768) & 22" (1680X1050) which might be using some good power from GPU and I have 2GB DDR2 800Mhz RAM.

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  • CPU Usage in Very Large Coherence Clusters

    - by jpurdy
    When sizing Coherence installations, one of the complicating factors is that these installations (by their very nature) tend to be application-specific, with some being large, memory-intensive caches, with others acting as I/O-intensive transaction-processing platforms, and still others performing CPU-intensive calculations across the data grid. Regardless of the primary resource requirements, Coherence sizing calculations are inherently empirical, in that there are so many permutations that a simple spreadsheet approach to sizing is rarely optimal (though it can provide a good starting estimate). So we typically recommend measuring actual resource usage (primarily CPU cycles, network bandwidth and memory) at a given load, and then extrapolating from those measurements. Of course there may be multiple types of load, and these may have varying degrees of correlation -- for example, an increased request rate may drive up the number of objects "pinned" in memory at any point, but the increase may be less than linear if those objects are naturally shared by concurrent requests. But for most reasonably-designed applications, a linear resource model will be reasonably accurate for most levels of scale. However, at extreme scale, sizing becomes a bit more complicated as certain cluster management operations -- while very infrequent -- become increasingly critical. This is because certain operations do not naturally tend to scale out. In a small cluster, sizing is primarily driven by the request rate, required cache size, or other application-driven metrics. In larger clusters (e.g. those with hundreds of cluster members), certain infrastructure tasks become intensive, in particular those related to members joining and leaving the cluster, such as introducing new cluster members to the rest of the cluster, or publishing the location of partitions during rebalancing. These tasks have a strong tendency to require all updates to be routed via a single member for the sake of cluster stability and data integrity. Fortunately that member is dynamically assigned in Coherence, so it is not a single point of failure, but it may still become a single point of bottleneck (until the cluster finishes its reconfiguration, at which point this member will have a similar load to the rest of the members). The most common cause of scaling issues in large clusters is disabling multicast (by configuring well-known addresses, aka WKA). This obviously impacts network usage, but it also has a large impact on CPU usage, primarily since the senior member must directly communicate certain messages with every other cluster member, and this communication requires significant CPU time. In particular, the need to notify the rest of the cluster about membership changes and corresponding partition reassignments adds stress to the senior member. Given that portions of the network stack may tend to be single-threaded (both in Coherence and the underlying OS), this may be even more problematic on servers with poor single-threaded performance. As a result of this, some extremely large clusters may be configured with a smaller number of partitions than ideal. This results in the size of each partition being increased. When a cache server fails, the other servers will use their fractional backups to recover the state of that server (and take over responsibility for their backed-up portion of that state). The finest granularity of this recovery is a single partition, and the single service thread can not accept new requests during this recovery. Ordinarily, recovery is practically instantaneous (it is roughly equivalent to the time required to iterate over a set of backup backing map entries and move them to the primary backing map in the same JVM). But certain factors can increase this duration drastically (to several seconds): large partitions, sufficiently slow single-threaded CPU performance, many or expensive indexes to rebuild, etc. The solution of course is to mitigate each of those factors but in many cases this may be challenging. Larger clusters also lead to the temptation to place more load on the available hardware resources, spreading CPU resources thin. As an example, while we've long been aware of how garbage collection can cause significant pauses, it usually isn't viewed as a major consumer of CPU (in terms of overall system throughput). Typically, the use of a concurrent collector allows greater responsiveness by minimizing pause times, at the cost of reducing system throughput. However, at a recent engagement, we were forced to turn off the concurrent collector and use a traditional parallel "stop the world" collector to reduce CPU usage to an acceptable level. In summary, there are some less obvious factors that may result in excessive CPU consumption in a larger cluster, so it is even more critical to test at full scale, even though allocating sufficient hardware may often be much more difficult for these large clusters.

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  • What is considered to be a "modification" of sources under the BSD license?

    - by Den
    I have a question about the 3-clause BSD license based on it's Wiki description. It states: Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: ... What is understood by "modification"? Specifically I am interested whether any/all of the following is considered as such modification: 1) reading the original sources and then re-implementing; 2) reading the original sources, waiting for a year and then re-implementing something based on whatever you could remember; 3) direct and very significant "complete" refactoring of the original sources.

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  • Is it unwise to blacklist an IP address?

    - by hawbsl
    We have a form on a commercial website which has been abused (but only once or twice) by someone from a particular IP address. A colleague wants to blacklist that IP address from the website. Seems to me that's overkill, and that there's a risk that genuine customers sharing that same IP address would be blacklisted too. I suppose a big part of my question is how many people might be sharing that same IP address and could be affected by our blacklist. I suspect that's a "how long's a piece of string" question but some ballpark answer would be really helpful. We're in the UK if that's significant.

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