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• Why don't scripting languages output Unicode to the Windows console?

  - by hippietrail

  The Windows console has been Unicode aware for at least a decade and perhaps as far back as Windows NT. However for some reason the major cross-platform scripting languages including Perl and Python only ever output various 8-bit encodings, requiring much trouble to work around. Perl gives a "wide character in print" warning, Pythong gives a charmap error and quits. Why on earth after all these years do they not just simply call the Win32 -W APIs that output UTF-16 Unicode instead of forcing everything through the ANSI/codepage bottleneck? Is it just that cross-platform performance is low priority? Is it that the languages use UTF-8 internally and find it too much bother to output UTF-16? Or are the -W APIs inherently broken to such a degree that they can't be used as-is?

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• Count of memory copies in *nix systems between packet at NIC and user application?

  - by Michael_73

  Hi there, This is just a general question relating to some high-performance computing I've been wondering about. A certain low-latency messaging vendor speaks in its supporting documentation about using raw sockets to transfer the data directly from the network device to the user application and in so doing it speaks about reducing the messaging latency even further than it does anyway (in other admittedly carefully thought-out design decisions). My question is therefore to those that grok the networking stacks on Unix or Unix-like systems. How much difference are they likely to be able to realise using this method? Feel free to answer in terms of memory copies, numbers of whales rescued or areas the size of Wales ;) Their messaging is UDP-based, as I understand it, so there's no problem with establishing TCP connections etc. Any other points of interest on this topic would be gratefully thought about! Best wishes, Mike

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• Time order of messages

  - by Aiden Bell

  Read (skimmed enough to get coding) through Erlang Programming and Programming Erlang. One question, which is as simple as it sounds: If you have a process Pid1 on machine m1 and a billion million messages are sent to Pid1, are messages handled in parallel by that process (I get the impression no) and(answered below) is there any guarantee of order when processing messages? ie. Received in order sent? If so, how is clock skew handled in high traffic situations for ordering? Coming from the whole C/Thread pools/Shared State background ... I want to get this concrete. I understand distributing an application, but want to ensure the 'raw bones' are what I expect before building processes and distributing workload. Also, am I right in thinking the whole world is currently flicking through Erlang texts ;)

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• Monitoring Reasoning Progress using the Pellet Reasoner

  - by Nico

  I am currently constructing an OWL ontology, which - until very recently classified rapidly using the Pellet reasoner. However, since the introduction of several new classes, the reasoning performance has slowed to a crawl. Although the reasoner completes and the ontology does not contain any unsatisfiable concepts etc, the time the reasoning takes is unacceptable. I am currently trying to track down the offending classes/class that may have led to the slowdown. Here's my question: is it possible to log the reasoning progreess of Pellet? I.e. is it possible to produce some output that will document how long pellet has spent on certain reasoning tasks/traces how long reasoning over any given class and axiom takes? If so, does anyone have some java code they could post up? Thanks in advance for your answers!

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• Morfik - suitability for medium-scale web enterprise applications

  - by MaikB

  I'm investigating technologies with which to develop a medium-scale (up to 100 or 200 simultaneous users) database-driven web application, and someone suggested Morfik. However, outside of the Morfik company I can find practically zero community support - no active blogs, no tutorials, no videos, no books - and this is of some concern (especially when compared to C# / ASP.NET / nHibernate etc support). Deciding between Morfik (untried and not used widely AFAIK) and the other technologies I mentioned (tried, tested, used widely) is becoming a critical issue for my company. Has anyone had success using Morfik in these kind of circumstances? What kind of performance did you achieve?

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• Validating Column Data Stored as CSV Against Another Table

  - by Jakkwylde

  I wanted to see what some suggested approaches would be to validate a field that is stored as a CSV against a table containing appropriate values. Althought it would be desired, it is NOT an option to split the CSV list into another related table. In the example data below I would be trying to capture the code 99 for widget A. Below is an example data representation. Table: Widgets WidgetName WidgetCodeList A 1, 2, 3 B 1 C 2, 3 D 99 Table: WidgetCodes WidgetCode 1 2 3 An earlier approach was to query the CSV column as rows using various string manipulations and CONNECT_BY_LEVEL however the performance was not acceptible.

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• Inserting an element into a sorted list

  - by Russell Cargill

  Ok I'm using getSharedPreferences to store my high score but before I fill it up I wanted to sort the scores into ascending order via and array, but if it finds a Score less than it in the first pos then it wont check the rest for the smallest? //function to add score to array and sort it public void addscoretoarray(int mScore){ for(int pos = 0; pos< score.length; pos++){ if(score[pos] > mScore){ //do nothing }else { //Add the score into that position score[pos] = mScore; break; } } sortArray(score); } should I call sortArray() before and after the loop to fix this problem or is there a better method to achive the same results? I should also mention that the sortArray(score) funtion is just calling Arrays.sort(score) where score is an array of mScore

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• JCarousellite not working in IE8

  - by eclipse31

  I have a user who's having issues running the JCarousellite plug-in in IE8. Not just on my own site, but also on the jcarousellite homepage (http://www.gmarwaha.com/jquery/jcarousellite/) It runs fine on my own machine and all his IE Security settings/levels are the same as my own (Secruity is at "Medium-High" and Privacy at "Medium"). JQuery also seems to be working for him as other aspects controlled by jquery on the site are functioning correctly. I use Firefox normally, so am not aware of every feature IE8 offers, but am thinking he has some setting/option set incorrectly. Anyone experienced something similar or have any suggestions for settings I could look at changing? Thanks

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• What could be adding "Pragma:no-cache" to my response Headers? (Apache, PHP)

  - by Daniel Magliola

  I have a website whose maintenance I've inherited, which is a big hairy mess. One of the things i'm doing is improving performance. Among other things, I'm adding Expires headers to images. Now, there are some images that are served through a PHP file, and I notice that they do have the Expires header, but they also get loaded every time. Looking at Response Headers, I see this: Expires Wed, 15 Jun 2011 18:11:55 GMT Cache-Control no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Pragma no-cache Which obviously explains the problem. Now, i've looked all over the code base, and it doesn't say "pragma" anywhere. .htaccess doesn't seem to have anything related either. Any ideas who could be setting those "pragma" (and "cache-control") headers, and how I can avoid it? Thanks! Daniel

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• Aggregate functions in ANSI SQL

  - by morpheous

  I want to use multiple aggregate functions in a query. All the examples i have seem on aggregate functions however, are trivial. Typically, they are of the form: SELECT field1,agg_func1, agg_func2 GROUP BY SOME_COLUMNS HAVING agg_func1 OP SOME_SCALAR Where: OP: is a boolean operator (e.g. <, = etc) SOME_SCALAR: is a scalar (i.e. a constant number) What I want to know is if it is possible to write (IN ANSI SQL) queries like: SELECT field1,agg_func1, agg_func2, agg_func3 GROUP BY SOME_COLUMNS HAVING (agg_func1 OP1 agg_func2) OP2 (agg_func2 OP3 agg_func3) Where: OP[N] are boolean operators or ANSI SQL clause operators like 'BETWEEN', 'LIKE', 'IN' etc. Also, assuming this is possible (I have not seen any documentation saying otherwise) are there any efficiency/performance considerations (i.e. penalties) when the HAVING clause consists of a boolean expression combining the output of the aggregate functions - instead of the normal comparison of the output of the aggregate with a constant number (e.g. min('salary') 100 ) - which is often used in the most banal examples involving aggregate functions?

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• LBA48 in Linux SCSI ATA Passthrough

  - by Ben Englert

  I am writing a custom disk monitoring/diagnostics app which, among other things, needs to do stuff to SATA disks behind a SAS PCI card under Linux. So far I am following this guide as well as the example code in sg_utils to pass ATA taskfiles through the SCSI layer. Seems to be working okay. However, in both cases, the CDB data structure (pointed to by the cmdp member of the sg_io argument to the ioctl) has only one unsigned char worth of space for the number of sectors. If you look at the ata_taskfile structure in linux\ata.h you'll see that it has an "nsect" and a "hob_nsect" field - high order bits for the sector count, to support LBA48. It turns out that in my application I need LBA48 support. So, anyone know how to set up an sg_io_hdr structure with an LBA48 sector count?

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• How can a Delphi TPersistent object calculate its own deserialization time?

  - by mjustin

  For performance tests I need a way to measure the time needed for a form to load its definition from the DFM. All existing forms inherit a custom form class. To capture the current time, this base class needs overriden methods as "extension points": start of the deserialization process after the deserialization (can be implemented by overriding the Loaded procedure) the moment just before the execution of the OnFormCreate event So the log for TMyForm.Create(nil) could look like: - 00.000 instance created - 00.010 before deserialization - 01.823 after deserialization - 02.340 before OnFormCreate Which TObject (or TComponent) methods are best suited? Maybe there are other extension points in the form creation process, please feel free to make suggestions.

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• Google App Engine - Dealing with concurrency issues of storing an object

  - by Spines

  My User object that I want to create and store in the datastore has an email, and a username. How do I make sure when creating my User object that another User object doesn't also have either the same email or the same username? If I just do a query to see if any other users have already used the username or the email, then there could be a race condition. UPDATE: The solution I'm currently considering is to use the MemCache to implement a locking mechanism. I would acquire 2 locks before trying to store the User object in the datastore. First a lock that locks based on email, then another that locks based on username. Since creating new User objects only happens at user registration time, and it's even rarer that two people try to use either the same username or the same email, I think it's okay to take the performance hit of locking. I'm thinking of using the MemCache locking code that is here: http://appengine-cookbook.appspot.com/recipe/mutex-using-memcache-api/ What do you guys think?

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• Leverage cloud and programming to share GB's of photos

  - by jcmoney

  My friends and I went on a trip and we have over 8 GB of photos we want to share. We live in different geographic locations and all of us (14 people) have a part of the 8 GB. I was wondering if there's a way to leverage my php skills to share all these photos. My current plan is to make a simple site that you can upload a bunch of files and also list those files for people to download (probably a compressed folder of a bunch of selected ones) but was wondering if there's a better way or if I'm grossly underestimating scalability issues. All of us have high speed internet (essentially T1) and I was planning on using Amazon EC2 since this is a heavy task but for a short time period. That's also the reason I can't use dropbox or similar services since they have a 2GB cap (and I don't want to have everyone sign up and install something). I also don't want to set up anything too tricky since not all of them are tech savvy.

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• How to have tortoisesvn Always freeze svn:externals for tags

  - by dnndeveloper

  Is this possible with tortoiseSVN?: Always freeze svn:externals for tags the scenario is our trunk will always use the 'head' revision for externals, however when we create 'tags' we would like for them to have a revision set for externals to properly 'freeze' them at a specific point in time. Thanks! Update Thanks to everyone for your feedback/info. Since I could not find anything that would completely meet our needs (tried smartsvn and svncopy.pl) I made a console app that so far has passed all our test cases. A high level overview: The app takes a repository URL then looks for all externals and adds the last commit revision for them - I do a "svn info" and get the "commit revision". The app works with both folder and single file externals. Here is the source code and complete setup files: http://svnxf.codeplex.com/

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• UNIX-style RegExp Replace running extremely slowly under windows. Help?

  - by John Sullivan

  I'm trying to run a unix regEXP on every log file in a 1.12 GB directory, then replace the matched pattern with ''. Test run on a 4 meg file is took about 10 minutes, but worked. Obviously something is murdering performance by several orders of magnitude. Find: ^(?!.*155[0-2][0-9]{4}\s.*).*$ -- NOTE: match any line NOT starting 152[0-2]NNNN where in is a number 0-9. Replace with: ''. Is there some justifiable reason for my regExp to take this long to replace matching text, or is the program I am using (this is windows / a program called "grepWin") most likely poorly optimized? Thanks.

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• WCF Rest services for use with the repository pattern?

  - by mark smith

  Hi there, I am considering moving my Service Layer and my data layer (repository pattern) to a WCF Rest service. So basically i would have my software installed locally (WPF client) which would call the Service Layer that exists via a Rest Service... The service layer would then call my data layer using a WCF Rest Service also OR maybe just call it via the DLL assembly I was hoping to understand what the performance would be like. Currently I have my datalayer and servicelayer installed locally via DLL Assemblies locally on the pc. Also i presume the WCF REST services won't support method overloading hance the same name but with a different signature?? I would really appreciate any feedback anyone can give. Thanks

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• How can I measure TForm deserialization time in Delphi?

  - by mjustin

  For performance tests I need a way to measure the time needed for a form to load its definition from the DFM. All existing forms inherit a custom form class. To capture the current time, this base class needs overriden methods as "extension points": before the beginning of the deserialization process after the completion of deserialization (can be implemented by overriding the Loaded procedure) the moment just before the execution of the OnFormCreate event Which TObject (or TComponent) methods are best suited? Maybe there are other extension points in the form creation process, please feel free to make suggestions.

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• Should I use a hosted version of JQuery? Which one?

  - by ataylor

  Should I use a local copy of jquery, or should I link to a copy provided by Google or Microsoft? I'm primarily concerned about speed. I've heard that just pulling content from other domains can have performance advantages related to how browsers limit connections. In particular, has anyone benchmarked the speed and latency of Google vs. Microsoft vs. local? Also, do I have to agree to any conditions or licenses to link from a third-party?

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• How to implement a mailing system with Rails that sends emails in the background

  - by Tam

  I want to implement a reliable mailing system with Ruby on Rails that sends emails in the background as sending email sometimes takes like 10 seconds or more so I don't want the user to wait. Some ideas I thought of: 1- Write to a table in DB a have a background process that go over and send email (concern: potential many reads/writes to DB slows down my application) 2- Messaging Queue background process / Rake task (concern: if server crashes queued mails will be lost also might eat up a lot of memory if many emails) I was wondering if you a know of a good solution that provides a balance between reliability and performance.

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• How to implement Voting for Grails Domain Classes?

  - by userWebMobile

  I have a Book class and need to implement a yes/no voting functionality. My domain classes look like this: class Book { String title static hasMany = [votes: Vote] } class User { String name static hasMany = [votes: Vote] } class Vote { boolean yesVote static belongsTo = [user: User, book: Book] } What is the best way to implement a voting for the book class. I need the following informations: What is the average yesVote for a book over all votes (either yes or no)? How to check if a specific user has done a vote? What is the best way to implement the computation of the average yesVote such that the performance does not drop?

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• Seeking tutorial: introduction to ODBC with Delphi

  - by mawg

  I have a lot of embedded C/C++/Ada experience and an outdated smattering of Delphi plus some database stuff. Now I have to implement an app in Delphi which can manipulate MySql, Oracle, maybe MS Access. In short, I need ODBC. I need to programmatically created a database, define its structure and populate its contents, then later query its existence and programmatically search. I would prefer not to use 3rd party components, unless there is a compelling reason to do so (performance ought not to be an issue for the app, it won't have much data or be run often, at least not in v1.0) . Can anyone point me at a tutorial which can get me up to speed? Thanks

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• Screening (multi)collinearity in a reggresion model

  - by aL3xa

  I hope that this one is not going to be "ask-and-answer" question... here goes: (multi)collinearity refers to extremely high correlations between predictors in the regression model. How to cure them... well, sometimes you don't need to "cure" collinearity, since it doesn't affect regression model itself, but interpretation of an effect of individual predictors. One way to spot collinearity is to put each predictor as a dependent variable, and other predictors as independent variables, determine R2, and if it's larger than .9 (or .95), we can consider predictor redundant. This is one "method"... what about other approaches? Some of them are time consuming, like excluding predictors from model and watching for b-coefficient changes - they should be noticeably different. Of course, we must always bare in mind specific context/goal of analysis... Sometimes, only remedy is to repeat a research, but right now, I'm interested in various ways of screening redundant predictors when (multi)collinearity occurs in a regression model.

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• Website content hosted with Google. Good or bad?

  - by user305052

  I recently decided to host my styles.css and various scripts on Google Docs and link them into my website. I also have all my images hosted through Picasa so that they too will load much faster and consistently across users. My site has most of its traffic from Japan, Africa, and South America, so I assume there will be a performance boost for my users since my server is hosted in Hong Kong. I (in Canada) have measured my load times to be half of what they used to be. Basically it's a free CDN for my personal stuff. I'm not too sure about all of this yet, so here's my question: what are the caveats of this setup?

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• How to implement square root and exponentiation on arbitrary length numbers?

  - by tomp

  I'm working on new data type for arbitrary length numbers (only non-negative integers) and I got stuck at implementing square root and exponentiation functions (only for natural exponents). Please help. I store the arbitrary length number as a string, so all operations are made char by char. Please don't include advices to use different (existing) library or other way to store the number than string. It's meant to be a programming exercise, not a real-world application, so optimization and performance are not so necessary. If you include code in your answer, I would prefer it to be in either pseudo-code or in C++. The important thing is the algorithm, not the implementation itself. Thanks for the help.

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