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  • Avoid an "out of memory error" in Java(eclipse), when using large data structure?

    - by gnomed
    OK, so I am writing a program that unfortunately needs to use a huge data structure to complete its work, but it is failing with a "out of memory error" during its initialization. While I understand entirely what that means and why it is a problem, I am having trouble overcoming it, since my program needs to use this large structure and I don't know any other way to store it. The program first indexes a large corpus of text files that I provide. This works fine. Then it uses this index to initialize a large 2D array. This array will have nXn entries, where "n" is the number of unique words in the corpus of text. For the relatively small chunk I am testing it on(about 60 files) it needs to make approximately 30,000x30,000 entries. this will probably be bigger once I run it on my full intended corpus too. It consistently fails every time, after it indexes, while it is initializing the data structure(to be worked on later). Things I have done include: revamp my code to use a primitive "int[]" instead of a "TreeMap" eliminate redundant structures, etc... Also, I have run eclipse with "eclipse -vmargs -Xmx2g" to max out my allocated memory I am fairly confident this is not going to be a simple line of code solution, but is most likely going to require a very new approach. I am looking for what that approach is, any ideas? Thanks, B.

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  • Recommendation for tool/framework that follows the naked objects pattern?

    - by Marcus Munzert
    I am searching for a tool/framework that follows the naked objects pattern and is written in Java. I know about tools like for instance JMatter, Naked Objects and Domain Object Explorer. That's not exactly what I am searching for, though. Open source would be great, but doesn't need to be. My intention is to use that tool/framework for the purpose of model-driven software development to do the modeling part. Ideally, such a tool/framework would provide the option to use JPA to store/load objects.

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  • Is CodeFirst intended for large scale applications?

    - by RoboShop
    I've been reading up on Entity Framework, in particular, EF 4.1 and following this link ( http://weblogs.asp.net/scottgu/archive/2010/07/16/code-first-development-with-entity-framework-4.aspx) and it's guide on Code First. I find it neat but I was wondering, is Code First supposed to be just a solution for rapid development where you can just jump right in without much planning or is it actually intended to be used for large scale applications?

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  • Mock Objects for Unit Testing

    - by user9009
    Hello How often QA engineers are responsible for developing Mock Objects for Unit Testing. So dealing with Mock Objects is just developer job ?. The reason i ask is i'm interested in QA as my career and am learning tools like JUnit , TestNG and couple of frameworks. I just want to know until what level of unit testing is done by developer and from what point QA engineer takes over testing for better test coverage ? Thanks

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  • Google I/O 2011: JavaScript Programming in the Large with Closure Tools

    Google I/O 2011: JavaScript Programming in the Large with Closure Tools Michael Bolin Most developers who have tinkered with JavaScript could not imagine writing 1000 lines of code in such a language, let alone 100000. Yet that is exactly what Google engineers have done using a suite of JavaScript tools named "Closure" to produce many of the most popular and sophisticated applications on the Web, such as Gmail and Google Maps. From: GoogleDevelopers Views: 4915 35 ratings Time: 57:07 More in Science & Technology

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  • Implementing the Security Development Lifecycle (SDL) at a Large Insurance Company

    Find out how Cigital, an SDL Pro Network member, assisted a large insurance company adopt the Microsoft SDL. The case study describes both the business drivers leading up to the company's recognizing the need for incorporating the SDL within their development process as well as the initial roll out of the SDL....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Advice on designing a robust program to handle a large library of meta-information & programs

    - by Sam Bryant
    So this might be overly vague, but here it is anyway I'm not really looking for a specific answer, but rather general design principles or direction towards resources that deal with problems like this. It's one of my first large-scale applications, and I would like to do it right. Brief Explanation My basic problem is that I have to write an application that handles a large library of meta-data, can easily modify the meta-data on-the-fly, is robust with respect to crashing, and is very efficient. (Sorta like the design parameters of iTunes, although sometimes iTunes performs more poorly than I would like). If you don't want to read the details, you can skip the rest Long Explanation Specifically I am writing a program that creates a library of image files and meta-data about these files. There is a list of tags that may or may not apply to each image. The program needs to be able to add new images, new tags, assign tags to images, and detect duplicate images, all while operating. The program contains an image Viewer which has tagging operations. The idea is that if a given image A is viewed while the library has tags T1, T2, and T3, then that image will have boolean flags for each of those tags (depending on whether the user tagged that image while it was open in the Viewer). However, prior to being viewed in the Viewer, image A would have no value for tags T1, T2, and T3. Instead it would have a "dirty" flag indicating that it is unknown whether or not A has these tags or not. The program can introduce new tags at any time (which would automatically set all images to "dirty" with respect to this new tag) This program must be fast. It must be easily able to pull up a list of images with or without a certain tag as well as images which are "dirty" with respect to a tag. It has to be crash-safe, in that if it suddenly crashes, all of the tagging information done in that session is not lost (though perhaps it's okay to loose some of it) Finally, it has to work with a lot of images (10,000) I am a fairly experienced programmer, but I have never tried to write a program with such demanding needs and I have never worked with databases. With respect to the meta-data storage, there seem to be a few design choices: Choice 1: Invidual meta-data vs centralized meta-data Individual Meta-Data: have a separate meta-data file for each image. This way, as soon as you change the meta-data for an image, it can be written to the hard disk, without having to rewrite the information for all of the other images. Centralized Meta-Data: Have a single file to hold the meta-data for every file. This would probably require meta-data writes in intervals as opposed to after every change. The benefit here is that you could keep a centralized list of all images with a given tag, ect, making the task of pulling up all images with a given tag very efficient

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  • SQL Developer Data Modeler v3.3 Early Adopter: Link Model Objects Across Designs

    - by thatjeffsmith
    The third post in our “What’s New in SQL Developer Data Modeler v3.3” series, SQL Developer Data Modeler now allows you to link objects across models. If you need to catch up on the earlier posts, here are the first two: New and Improved Search Collaborative Design via Excel Today’s post is a very simple and straightforward discussion on how to share objects across models and designs. In previous releases you could easily copy and paste objects between models and designs. Simply select your object, right-click and select ‘Copy’ Once copied, paste it into your other designs and then make changes as required. Once you paste the object, it is no longer associated with the source it was copied from. You are free to make any changes you want in the new location without affecting the source material. And it works the other way as well – make any changes to the source material and the new object is also unaffected. However. What if you want to LINK a model object instead of COPYING it? In version 3.3, you can now do this. Simply drag and drop the object instead of copy and pasting it. Select the object, in this case a relational model table, and drag it to your other model. It’s as simple as it sounds, here’s a little animated GIF to show you what I’m talking about. Drag and drop between models/designs to LINK an object Notes The ‘linked’ object cannot be modified from the destination space Updating the source object will propagate the changes forward to wherever it’s been linked You can drag a linked object to another design, so dragging from A - B and then from B - C will work Linked objects are annotated in the model with a ‘Chain’ bitmap, see below This object has been linked from another design/model and cannot be modified. A very simple feature, but I like the flexibility here. Copy and paste = new independent object. Drag and drop = linked object.

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  • Should I return iterators or more sophisticated objects?

    - by Erik
    Say I have a function that creates a list of objects. If I want to return an iterator, I'll have to return iter(a_list). Should I do this, or just return the list as it is? My motivation for returning an iterator is that this would keep the interface smaller -- what kind of container I create to collect the objects is essentially an implementation detail On the other hand, it would be wasteful if the user of my function may have to recreate the same container from the iterator which would be bad for performance.

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  • Deleting Large Number of Records

    Often someone will try to perform a delete on a large number of records and run into a number of problems. Slow performance, log growth, and more. Lynn Pettis shows us how to better handle this situation in SQL Server 2000 and SQL Server 2005 The Future of SQL Server Monitoring "Being web-based, SQL Monitor 2.0 enables you to check on your servers from almost any location" Jonathan Allen.Try SQL Monitor now.

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  • Hiding System Objects in Object Explorer in SQL Server Management Studio

    While looking through the new features and improvements in SQL Server Management Studio (SSMS) we found a potentially interesting one to Hide System Objects in Object Explorer in SQL Server Management Studio. In this tip we will take a look at how to Hide System Objects in Object Explorer. Join SQL Backup’s 35,000+ customers to compress and strengthen your backups "SQL Backup will be a REAL boost to any DBA lucky enough to use it." Jonathan Allen. Download a free trial now.

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  • FREE EBus (ATG) webcast on Troubleshooting Invalid Objects

    - by cwarticki
    v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} E-Business Suite Applications Technology Group (ATG) Advisor Webcast Program Invitation : Advisor Webcast December 2012 In December 2012 we have scheduled an Advisor Webcast, where we want to give you a closer look into the invalid objects in an E-Business Suite Environment. E-Business Suite – Troubleshooting invalid objects Agenda : · Introduction · Activities that generate invalid objects · EBS Architecture · EBS Patching Concepts · Troubleshooting Invalid Objects · References EMEA Session : o Tuesday December 11th, 2012 o at 09:00 AM UK / 10:00 AM CET / 13:30 India / 17:00 Japan / 18:00 Australia o Details & Registration : Note 1501696.1 o Direct link to register in WebEx US Session : o Wednesday December 12th, 2012 o at 18:00 UK / 19:00 CET / 10:00 AM Pacific / 11:00 AM Mountain/ 01:00 PM Eastern o Details & Registration : Note 1501697.1 o Direct link to register in WebEx If you have any question about the schedules or if you have a suggestion for an Advisor Webcast to be planned in future, please send an E-Mail to Ruediger Ziegler.

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  • MySQL Binary Storage using BLOB VS OS File System: large files, large quantities, large problems.

    - by Quantico773
    Hi Guys, Versions I am running (basically latest of everything): PHP: 5.3.1 MySQL: 5.1.41 Apache: 2.2.14 OS: CentOS (latest) Here is the situation. I have thousands of very important documents, ranging from customer contracts to voice signatures (recordings of customer authorisation for contracts), with file types including, but not limited to jpg, gif, png, tiff, doc, docx, xls, wav, mp3, pdf, etc. All of these documents are currently stored on several servers including Windows 32 bit, CentOS and Mac, among others. Some files are also stored on employees desktop computers and laptops, and some are still hard copies stored in hundreds of boxes and filing cabinets. Now because customers or lawyers could demand evidence of contracts at any time, my company has to be able to search and locate the correct document(s) effectively, for this reason ALL of these files have to be digitised (if not already) and correlated into some sort of order for searching and accessing. As the programmer, I have created a full Customer Relations Management tool that the whole company uses. This includes Customer Profiles management, Order and job Tracking tools, Job/sale creation and management modules, etc, and at the moment any file that is needed at a customer profile level (drivers licence, credit authority, etc) or at a job/sale level (contracts, voice signatures, etc) can be uploaded to the server and sits in a parent/child hierarchy structure, just like Windows Explorer or any other typical file managment model. The structure appears as such: drivers_license |- DL_123.jpg voice_signatures |- VS_123.wav |- VS_4567.wav contracts So the files are uplaoded using PHP and Apache, and are stored in the file system of the OS. At the time of uploading, certain information about the file(s) is stored in a MySQL database. Some of the information stored is: TABLE: FileUploads FileID CustomerID (the customer id that the file belongs to, they all have this.) JobID/SaleID (the id of the job/sale associated, if any.) FileSize FileType UploadedDateTime UploadedBy FilePath (the directory path the file is stored in.) FileName (current file name of uploaded file, combination of CustomerID and JobID/SaleID if applicable.) FileDescription OriginalFileName (original name of the source file when uploaded, including extension.) So as you can see, the file is linked to the database by the File Name. When I want to provide a customers' files for download to a user all I have to do is "SELECT * FROM FileUploads WHERE CustomerID = 123 OR JobID = 2345;" and this will output all the file details I require, and with the FilePath and FileName I can provide the link for download. http... server / FilePath / FileName There are a number of problems with this method: Storing files in this "database unconcious" environment means data integrity is not kept. If a record is deleted, the file may not be deleted also, or vice versa. Files are strewn all over the place, different servers, computers, etc. The file name is the ONLY thing matching the binary to the database and customer profile and customer records. etc, etc. There are so many reasons, some of which are described here: http://www.dreamwerx.net/site/article01 . Also there is an interesting article here too: sietch.net/ViewNewsItem.aspx?NewsItemID=124 . SO, after much research I have pretty much decided I am going to store ALL of these files in the database, as a BLOB or LONGBLOB, but there are still many considerations before I do this. I know that storing them in the database is a viable option, however there are a number of methods of storing them. I also know storing them is one thing; correlating and accessing them in a manageable way is another thing entirely. The article provided at this link: dreamwerx.net/site/article01 describes a way of splitting the uploaded binary files into 64kb chunks and storing each chunk with the FileID, and then streaming the actual binary file to the client using headers. This is a really cool idea since it alleviates preassure on the servers memory; instead of loading an entire 100mb file into the RAM and then sending it to the client, it is doing it 64kb at a time. I have tried this (and updated his scripts) and this is totally successful, in a very small frame of testing. So if you are in agreeance that this method is a viable, stable and robust long-term option to store moderately large files (1kb to couple hundred megs), and large quantities of these files, let me know what other considerations or ideas you have. Also, I am considering getting a current "File Management" PHP script that gives an interface for managing files stored in the File System and converting it to manage files stored in the database. If there is already any software out there that does this, please let me know. I guess there are many questions I could ask, and all the information is up there ^^ so please, discuss all aspects of this and we can pass ideas back and forth and teach each other. Cheers, Quantico773

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  • Is there a distributed VCS that can manage large files?

    - by joelhardi
    Is there a distributed version control system (git, bazaar, mercurial, darcs etc.) that can handle files larger than available RAM? I need to be able to commit large binary files (i.e. datasets, source video/images, archives), but I don't need to be able to diff them, just be able to commit and then update when the file changes. I last looked at this about a year ago, and none of the obvious candidates allowed this, since they're all designed to diff in memory for speed. That left me with a VCS for managing code and something else ("asset management" software or just rsync and scripts) for large files, which is pretty ugly when the directory structures of the two overlap.

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  • How to insert large files in mysql database using php? [closed]

    - by anjan
    Hi! I want to upload a large file of size 10M max to my mysql database. Using .htaccess i changed the PHP's own file upload limit to "10485760" = 10M, i am able to upload files upto 10M size without any problem. But i can not insert the file in database if it is more that 1M in size. i am using file_get_contents to read all file data and pass it to the insert query as a string to be inserted into a LONGBLOB field. But files with more than 1M size is not being added to database, though i can use print_r($_FILES) to examine that the file uploaded correctly. Any help will be appreciated and i will need it within next 6 hours. So, please help! best regards, Anjan * This is a duplicate of http://stackoverflow.com/questions/492549/how-can-i-insert-large-files-in-mysql-db-using-php *

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  • Iterating over a large data set in long running Python process - memory issues?

    - by user1094786
    I am working on a long running Python program (a part of it is a Flask API, and the other realtime data fetcher). Both my long running processes iterate, quite often (the API one might even do so hundreds of times a second) over large data sets (second by second observations of certain economic series, for example 1-5MB worth of data or even more). They also interpolate, compare and do calculations between series etc. What techniques, for the sake of keeping my processes alive, can I practice when iterating / passing as parameters / processing these large data sets? For instance, should I use the gc module and collect manually? Any advice would be appreciated. Thanks!

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  • Overly accessible and incredibly resource hungry relationships between business objects. How can I f

    - by Mike
    Hi, Firstly, This might seem like a long question. I don't think it is... The code is just an overview of what im currently doing. It doesn't feel right, so I am looking for constructive criticism and warnings for pitfalls and suggestions of what I can do. I have a database with business objects. I need to access properties of parent objects. I need to maintain some sort of state through business objects. If you look at the classes, I don't think that the access modifiers are right. I don't think its structured very well. Most of the relationships are modelled with public properties. SubAccount.Account.User.ID <-- all of those are public.. Is there a better way to model a relationship between classes than this so its not so "public"? The other part of this question is about resources: If I was to make a User.GetUserList() function that returns a List, and I had 9000 users, when I call the GetUsers method, it will make 9000 User objects and inside that it will make 9000 new AccountCollection objects. What can I do to make this project not so resource hungry? Please find the code below and rip it to shreds. public class User { public string ID {get;set;} public string FirstName {get; set;} public string LastName {get; set;} public string PhoneNo {get; set;} public AccountCollection accounts {get; set;} public User { accounts = new AccountCollection(this); } public static List<Users> GetUsers() { return Data.GetUsers(); } } public AccountCollection : IEnumerable<Account> { private User user; public AccountCollection(User user) { this.user = user; } public IEnumerable<Account> GetEnumerator() { return Data.GetAccounts(user); } } public class Account { public User User {get; set;} //This is public so that the subaccount can access its Account's User's ID public int ID; public string Name; public Account(User user) { this.user = user; } } public SubAccountCollection : IEnumerable<SubAccount> { public Account account {get; set;} public SubAccountCollection(Account account) { this.account = account; } public IEnumerable<SubAccount> GetEnumerator() { return Data.GetSubAccounts(account); } } public class SubAccount { public Account account {get; set;} //this is public so that my Data class can access the account, to get the account's user's ID. public SubAccount(Account account) { this.account = account; } public Report GenerateReport() { Data.GetReport(this); } } public static class Data { public static List<Account> GetSubAccounts(Account account) { using (var dc = new databaseDataContext()) { List<SubAccount> query = (from a in dc.Accounts where a.UserID == account.User.ID //this is getting the account's user's ID select new SubAccount(account) { ID = a.ID, Name = a.Name, }).ToList(); } } public static List<Account> GetAccounts(User user) { using (var dc = new databaseDataContext()) { List<Account> query = (from a in dc.Accounts where a.UserID == User.ID //this is getting the user's ID select new Account(user) { ID = a.ID, Name = a.Name, }).ToList(); } } public static Report GetReport(SubAccount subAccount) { Report report = new Report(); //database access code here //need to get the user id of the subaccount's account for data querying. //i've got the subaccount, but how should i get the user id. //i would imagine something like this: int accountID = subAccount.Account.User.ID; //but this would require the subaccount's Account property to be public. //i do not want this to be accessible from my other project (UI). //reading up on internal seems to do the trick, but within my code it still feels //public. I could restrict the property to read, and only private set. return report; } public static List<User> GetUsers() { using (var dc = new databaseDataContext()) { var query = (from u in dc.Users select new User { ID = u.ID, FirstName = u.FirstName, LastName = u.LastName, PhoneNo = u.PhoneNo }).ToList(); return query; } } }

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  • Rebuilding CoasterBuzz, Part II: Hot data objects

    - by Jeff
    This is the second post, originally from my personal blog, in a series about rebuilding one of my Web sites, which has been around for 12 years. More: Part I: Evolution, and death to WCF After the rush to get moving on stuff, I temporarily lost interest. I went almost two weeks without touching the project, in part because the next thing on my backlog was doing up a bunch of administrative pages. So boring. Unfortunately, because most of the site's content is user-generated, you need some facilities for editing data. CoasterBuzz has a database full of amusement parks and roller coasters. The entities enjoy the relationships that you would expect, though they're further defined by "instances" of a coaster, to define one that has moved between parks as one, with different names and operational dates. And of course, there are pictures and news items, too. It's not horribly complex, except when you have to account for a name change and display just the newest name. In all previous versions, data access was straight SQL. As so much of the old code was rooted in 2003, with some changes in 2008, there wasn't much in the way of ORM frameworks going on then. Let me rephrase that, I mostly wasn't interested in ORM's. Since that time, I used a little LINQ to SQL in some projects, and a whole bunch of nHibernate while at Microsoft. Through all of that experience, I have to admit that these frameworks are often a bigger pain in the ass than not. They're great for basic crud operations, but when you start having all kinds of exotic relationships, they get difficult, and generate all kinds of weird SQL under the covers. The black box can quickly turn into a black hole. Sometimes you end up having to build all kinds of new expertise to do things "right" with a framework. Still, despite my reservations, I used the newer version of Entity Framework, with the "code first" modeling, in a science project and I really liked it. Since it's just a right-click away with NuGet, I figured I'd give it a shot here. My initial effort was spent defining the context class, which requires a bit of work because I deviate quite a bit from the conventions that EF uses, starting with table names. Then throw some partial querying of certain tables (where you'll find image data), and you're splitting tables across several objects (navigation properties). I won't go into the details, because these are all things that are well documented around the Internet, but there was a minor learning curve there. The basics of reading data using EF are fantastic. For example, a roller coaster object has a park associated with it, as well as a number of instances (if it was ever relocated), and there also might be a big banner image for it. This is stupid easy to use because it takes one line of code in your repository class, and by the time you pass it to the view, you have a rich object graph that has everything you need to display stuff. Likewise, editing simple data is also, well, simple. For this goodness, thank the ASP.NET MVC framework. The UpdateModel() method on the controllers is very elegant. Remember the old days of assigning all kinds of properties to objects in your Webforms code-behind? What a time consuming mess that used to be. Even if you're not using an ORM tool, having hydrated objects come off the wire is such a time saver. Not everything is easy, though. When you have to persist a complex graph of objects, particularly if they were composed in the user interface with all kinds of AJAX elements and list boxes, it's not just a simple matter of submitting the form. There were a few instances where I ended up going back to "old-fashioned" SQL just in the interest of time. It's not that I couldn't do what I needed with EF, it's just that the efficiency, both my own and that of the generated SQL, wasn't good. Since EF context objects expose a database connection object, you can use that to do the old school ADO.NET stuff you've done for a decade. Using various extension methods from POP Forums' data project, it was a breeze. You just have to stick to your decision, in this case. When you start messing with SQL directly, you can't go back in the same code to messing with entities because EF doesn't know what you're changing. Not really a big deal. There are a number of take-aways from using EF. The first is that you write a lot less code, which has always been a desired outcome of ORM's. The other lesson, and I particularly learned this the hard way working on the MSDN forums back in the day, is that trying to retrofit an ORM framework into an existing schema isn't fun at all. The CoasterBuzz database isn't bad, but there are design decisions I'd make differently if I were starting from scratch. Now that I have some of this stuff done, I feel like I can start to move on to the more interesting things on the backlog. There's a lot to do, but at least it's fun stuff, and not more forms that will be used infrequently.

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  • Using WKA in Large Coherence Clusters (Disabling Multicast)

    - by jpurdy
    Disabling hardware multicast (by configuring well-known addresses aka WKA) will place significant stress on the network. For messages that must be sent to multiple servers, rather than having a server send a single packet to the switch and having the switch broadcast that packet to the rest of the cluster, the server must send a packet to each of the other servers. While hardware varies significantly, consider that a server with a single gigabit connection can send at most ~70,000 packets per second. To continue with some concrete numbers, in a cluster with 500 members, that means that each server can send at most 140 cluster-wide messages per second. And if there are 10 cluster members on each physical machine, that number shrinks to 14 cluster-wide messages per second (or with only mild hyperbole, roughly zero). It is also important to keep in mind that network I/O is not only expensive in terms of the network itself, but also the consumption of CPU required to send (or receive) a message (due to things like copying the packet bytes, processing a interrupt, etc). Fortunately, Coherence is designed to rely primarily on point-to-point messages, but there are some features that are inherently one-to-many: Announcing the arrival or departure of a member Updating partition assignment maps across the cluster Creating or destroying a NamedCache Invalidating a cache entry from a large number of client-side near caches Distributing a filter-based request across the full set of cache servers (e.g. queries, aggregators and entry processors) Invoking clear() on a NamedCache The first few of these are operations that are primarily routed through a single senior member, and also occur infrequently, so they usually are not a primary consideration. There are cases, however, where the load from introducing new members can be substantial (to the point of destabilizing the cluster). Consider the case where cluster in the first paragraph grows from 500 members to 1000 members (holding the number of physical machines constant). During this period, there will be 500 new member introductions, each of which may consist of several cluster-wide operations (for the cluster membership itself as well as the partitioned cache services, replicated cache services, invocation services, management services, etc). Note that all of these introductions will route through that one senior member, which is sharing its network bandwidth with several other members (which will be communicating to a lesser degree with other members throughout this process). While each service may have a distinct senior member, there's a good chance during initial startup that a single member will be the senior for all services (if those services start on the senior before the second member joins the cluster). It's obvious that this could cause CPU and/or network starvation. In the current release of Coherence (3.7.1.3 as of this writing), the pure unicast code path also has less sophisticated flow-control for cluster-wide messages (compared to the multicast-enabled code path), which may also result in significant heap consumption on the senior member's JVM (from the message backlog). This is almost never a problem in practice, but with sufficient CPU or network starvation, it could become critical. For the non-operational concerns (near caches, queries, etc), the application itself will determine how much load is placed on the cluster. Applications intended for deployment in a pure unicast environment should be careful to avoid excessive dependence on these features. Even in an environment with multicast support, these operations may scale poorly since even with a constant request rate, the underlying workload will increase at roughly the same rate as the underlying resources are added. Unless there is an infrastructural requirement to the contrary, multicast should be enabled. If it can't be enabled, care should be taken to ensure the added overhead doesn't lead to performance or stability issues. This is particularly crucial in large clusters.

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  • Java: I've created a list of word objects to include the name and the frequency, but having trouble

    - by adam08
    Hi Everyone, I'm working on a project which has a dictionary of words and I'm extracting them and adding them to an ArrayList as word objects. I have a class called Word as below. What I'm wondering is how do I access these word objects to update the frequency? As part of this project, I need to only have one unique word, and increase the frequency of that word by the number of occurrences in the dictionary. Word(String word) { this.word = word; this.freq = 0; } public String getWord() { return word; } public int getFreq() { return freq; } public void setFreq() { freq = freq + 1; } This is how I am adding the word objects to the ArrayList...I think it's ok? String pattern = "[^a-zA-Z\\s]"; String strippedString = line.replaceAll(pattern, ""); line = strippedString.toLowerCase(); StringTokenizer st = new StringTokenizer(line); while (st.hasMoreTokens()) { String newWord = st.nextToken(); word.add(new Word(newWord)); count++; }

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  • SQL: Order randomly when inserting objects to a table

    - by Ekaterina
    I have an UDF that selects top 6 objects from a table (with a union - code below) and inserts it into another table. (btw SQL 2005) So I paste the UDF below and what the code does is: selects objects for a specific city and add a level to those (from table Europe) union that selection with a selection from the same table for objects that are from the same country and add a level to those From the union, selection is made to get top 6 objects, order by level, so the objects from the same city will be first, and if there aren't any available, then objects from the same country will be returned from the selection. And my problem is, that I want to make a random selection to get random objects from table Europe, but because I insert the result of my selection into a table, I can't use order by newid() or rand() function because they are time-dependent, so I get the following errors: Invalid use of side-effecting or time-dependent operator in 'newid' within a function. Invalid use of side-effecting or time-dependent operator in 'rand' within a function. UDF: ALTER FUNCTION [dbo].[Objects] (@id uniqueidentifier) RETURNS @objects TABLE ( ObjectId uniqueidentifier NOT NULL, InternalId uniqueidentifier NOT NULL ) AS BEGIN declare @city varchar(50) declare @country int select @city = city, @country = country from Europe where internalId = @id insert @objects select @id, internalId from ( select distinct top 6 [level], internalId from ( select top 6 1 as [level], internalId from Europe N4 where N4.city = @city and N4.internalId != @id union select top 6 2 as [level], internalId from Europe N5 where N5.countryId = @country and N5.internalId != @id ) as selection_1 order by [level] ) as selection_2 return END If you have fresh ideas, please share them with me. (Just please, don't suggest to order by newid() or to add a column rand() with seed DateTime (by ms or sthg), because that won't work.)

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