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• Multiple indexes for a Java Collection - most basic solution?

  - by chris_l

  Hi, I'm looking for the most basic solution to create multiple indexes on a Java Collection. Required functionality: When a Value is removed, all index entries associated with that value must be removed. Index lookup must be faster than linear search (at least as fast as a TreeMap). Side conditions: It should ideally work with JavaSE (6.0) alone - no extra libraries, if possible. If necessary, then only small (not something like Lucene), common and well tested libraries. No database! Of course, I could write a class that manages multiple Maps myself. But I'd like to know, if it can be done without - while still getting a simple usage similar to using a single indexed java.util.Map. Thanks, Chris

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• Python IPC, popen too slow

  - by UnableToLoad

  i need to run a subprocess (./myProgram) form python script and get output, actually i do this: import subprocess proc = subprocess.Popen('./generate_out', shell=False, stdout=subprocess.PIPE, ) while proc.poll() is None: out = proc.stdout.readline() data = doStuff(out) print(data) but is slow, sometimes pass a lot of time between the output produced by ./generate_out and the print(data), knowing that my doStuff() function is very fast, i think there is some buffer slowing down my pipe... Notes: ./generate_out, generates potentially an unlimited number of lines of finite length each. It seems that when too few chars are put in the pipe between the two processes nothing happens, then when enough is produced i get a huge print (non the expected behaviour!) sometimes i wait many seconds (10-20 and more) between generate_out print and python print) what can i do? maybe communicate() is faster? anithing else? Thank you a lot!

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• What are some good ways to do intermachine locking?

  - by mike

  Our server cluster consists of 20 machines, each with 10 pids of 5 threads. We'd like some way to prevent any two threads, in any pid, on any machine, from modifying the same object at the same time. Our code's written in Python and runs on Linux, if that helps narrow things down. Also, it's a pretty rare case that two such threads want to do this, so we'd prefer something that optimizes the "only one thread needs this object" case to be really fast, even if it means that the "one thread has locked this object and another one needs it" case isn't great. What are some of the best practices?

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• Efficient implementation of natural logarithm (ln) and exponentiation

  - by Donotalo

  Basically, I'm looking for implementation of log() and exp() functions provided in C library <math.h>. I'm working with 8 bit microcontrollers (OKI 411 and 431). I need to calculate Mean Kinetic Temperature. The requirement is that we should be able to calculate MKT as fast as possible and with as little code memory as possible. The compiler comes with log() and exp() functions in <math.h>. But calling either function and linking with the library causes the code size to increase by 5 Kilobytes, which will not fit in one of the micro we work with (OKI 411), because our code already consumed ~12K of available ~15K code memory. The implementation I'm looking for should not use any other C library functions (like pow(), sqrt() etc). This is because all library functions are packed in one library and even if one function is called, the linker will bring whole 5K library to code memory.

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• Silverlight 4 application on localhost runs extremely slow

  - by rams

  Silverlight 4 app running in IE8 and hosted on VS2010 internal webserver. The website takes atleast a minute to download the xap and code runs slow on client (IE8). I am running the app in debug mode and have turned intellitrace off. Symbol loading is also turned off. However if I kill the VS webserver, clean the solution, the app runs fast. 3 debugging sessions later, the app slows to a crawl. Have also tried turning off McAfee live scanning but no use. Looked in event log for any clue but found none. What could be the cause of the slowness? TIA rams

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• Trying to find a good javascript function for hmac-sha1

  - by Darxval

  So i have been searching the web for a javascript source for an Hmac-sha1 algorithm. I saw Crypto's but i cant seem to get it to work, mainly because it has no idea what crypto means. (i copied the .js script functions into my script file) http://code.google.com/p/crypto-js/ I have my base64 encoded function already. that i got from here: http://nerds-central.blogspot.com/2007/01/fast-scalable-javascript-and-vbscript.html btw this for a twitter application using the new OAuth system. any help or links to where i can find anything on this would be helpful If you need me to elaborate let me know. thank you!

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• Retrieving data from database. Retrieve only when needed or get everything?

  - by RHaguiuda

  I have a simple application to store Contacts. This application uses a simple relational database to store Contact information, like Name, Address and other data fields. While designing it, I question came to my mind: When designing programs that uses databases, should I retrieve all database records and store them in objects in my program, so I have a very fast performance or I should always gather data only when required? Of course, retrieving all data can only be done if it`s not too many, but do you use this approach when you make sure that the database will be small (< 300 records for example)? I have designed once a similar application that fetches data only when needed, but that was slow (using a Access database). Thanks for all help.

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• which layout engine for finding coordinates of html elements on the web page?

  - by Mexx

  I am doing some web data classification task and was thinking if I could get the co-ordinates of html elements as they would appear on a web-browser without taking into consideration any css or javascript being referred in the web page. My language of programming is c++ and the need results for a couple million of pages, so it has to be fast. I know there is a Microsoft COM component which renders the page in a web browser control and then can be queried for position of different html tags. But this is not suitable in my case as it first renders the whole page which takes up a lot of time. So as I found out, there are open-source layout engines WebKit, Gecko that can probably be used for this. But that's a huge piece of code and I need someone to direct me to the right classes or right modules to look into or any previous/similar work someone has done previously. Also, please let me know what you guys think is a good choice if I want to customize the existing code for use with multiple threads to make it faster. Thanks

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• Is it possible to generate plain-old XML using Haml?

  - by lsdr

  I've been working on a piece of software where I need to generate a custom XML file to send back to a client application. The current solutions on Ruby/Rails world for generating XML files are slow, at best. Using builder or event Nokogiri, while have a nice syntax and are maintainable solutions, they consume too much time and processing. I definetly could go to ERB, which provides a good speed at the expense of building the whole XML by hand. HAML is a great tool, have a nice and straight-forward syntax and is fairly fast. But I'm struggling to build pure XML files using it. Which makes me wonder, is it possible at all? Does any one have some pointers to some code or docs showing how to do this, build a full, valid XML from HAML?

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• imported vm gives "failed to open/create network" error

  - by Colleen

  steps: 1. created a vm in windows 2. partitioned drive and installed ubuntu 3. exported the vm I created 4. mounted windows drive in ubuntu 5. imported the vm from the export, in the mounted drive 6. tried to start vm, got the following error: "Failed to open a session for the virtual machine XXXX. Failed to open/create the internal network 'HostInterfaceNetworking-Intel(R) 82579LM Gigabit Network Connection' (you might need to modprobe vboxnetflt to make it accessible) (VERR_INTNET_FLT_IF_NOT_FOUND). Result Code: NS_ERROR_FAILURE (0x80004005) Component: Console Interface: IConsole {1968b7d3-e3bf-4ceb-99e0-cb7c913317bb} " Network settings: Adapter 1: PCnet-FAST III (Bridged adapter, Intel(R) 82579LM Gigabit Network Connection)

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• Operations on bytes in C#

  - by Hooch

  Hello. I'm writing application to control LEDS on LPT. I have everything working except this. This is one small function. I have sth like that: I want to build function that will take two argument and return one number: In actual code those binary numers will be in hex. I put them there like that so that it's easier for you to visualize it. Example1: arg1 = 1100 1100 arg2 = 1001 0001 retu = 0100 1100 Example2: arg1 = 1111 1111 arg2 = 0001 0010 retu = 1110 1101 Example3: arg1 = 1111 0000 arg2 = 0010 0010 retu = 1101 0000 I have no idea how this function should look like. I want it to be as fast as possible. I'll call this function 200 times per second.

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• Which language + framework should I use for building standalone clients for my PHP webapp?

  - by Jagira

  Hello, I have a PHP web application which basically maintains a set of user profiles and their records. My users are using the app via browser. I am planning to build a standalone desktop client/app for WINDOWS OS, in which a user can login, retrieve and modify the records. Which language + framework will be simple, fast and lightweight to use? I can think of the following options: Microsoft Visual Basic - simplest? Microsoft Visual C++ Python PHP + bambalam compiler Are there any other options? And which of these is better?

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• Slow query with unexpected scan

  - by zerkms

  Hello I have this query: SELECT * FROM SAMPLE SAMPLE INNER JOIN TEST TEST ON SAMPLE.SAMPLE_NUMBER = TEST.SAMPLE_NUMBER INNER JOIN RESULT RESULT ON TEST.TEST_NUMBER = RESULT . TEST_NUMBER WHERE SAMPLED_DATE BETWEEN '2010-03-17 09:00' AND '2010-03-17 12:00' the biggest table here is RESULT, contains 11.1M records. The left 2 tables about 1M. this query works slowly (more than 10 minutes) and returns about 800 records. executing plan shows clustered index scan over all 11M records. RESULT.TEST_NUMBER is a clustered primary key. if I change 2010-03-17 09:00 to 2010-03-17 10:00 - i get about 40 records. it executes for 300ms. and plan shows clustered index seek if i replace * in SELECT clause to RESULT.TEST_NUMBER (covered with index) - then all become fast in first case too. this points to hdd io issues, but doesn't clarifies changing plan. so, any ideas?

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• Scalable (half-million files) version control system

  - by hashable

  We use SVN for our source-code revision control and are experimenting using it for non-source-code files. We are working with a large set (300-500k) of short (1-4kB) text files that will be updated on a regular basis and need to version control it. We tried using SVN in flat-file mode and it is struggling to handle the first commit (500k files checked in) taking about 36 hours. On a daily basis, we need the system to be able to handle 10k modified files per commit transaction in a short time (<5 min). My questions: Is SVN the right solution for my purpose. The initial speed seems too slow for practical use. If Yes, is there a particular svn server implementation that is fast? (We are currently using the gnu/linux default svn server and command line client.) If No, what are the best f/oss/commercial alternatives Thanks

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• C++ union assignment, is there a good way to do this?

  - by Sqeaky

  I am working on a project with a library and I must work with unions. Specifically I am working with SDL and the SDL_Event union. I need to make copies of the SDL_Events, and I could find no good information on overloading assignment operators with unions. Provided that I can overload the assignment operator, should I manually sift through the union members and copy the pertinent members or can I simply come some members (this seems dangerous to me), or maybe just use memcpy() (this seems simple and fast, but slightly dangerous)? If I can't overload operators what would my best options be from there? I guess I could make new copies and pass around a bunch of pointers, but in this situation I would prefer not to do that. Any ideas welcome!

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• Is Sphinx better than LaTex in writing manuals/books?

  - by Masi

  Only a few people recommended to use Sphinx at the beginning of the year. Sphinx has developed rather fast recently. I noted today that Sage has made a change from direct editing with LaTex to Sphinx. This is evident in William Stein's answer on 2nd April about Sage's tutorial The tutorial is not a latex document anymore. It's an entirely different Sphinx document that can output pdf. It suggests me that Sphinx may be at a level such that it is suitable for me. Is Sphinx better than LaTex in writing manuals/books?

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• Windows Workflow runs very slowlyh on my DEV machine

  - by Joon

  I am developing an app using WF hosted in IIS as WCF services as a business layer. This runs quickly on any machine running Windows Server 2008 R2, but very slowly on our dev machines, running Windows XP SP3. Yesterday, the workflows were as fast on my dev machine as they are on the server for the whole day. Today, they are back to running slowly again (I rebooted overnight) Has anyone else experienced this problem with workflows running slowly on IIS in XP? What did you do to fix it?

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• Best Application for storing code snippets

  - by Konrad

  Hi all, Just wondering if you can point me in the direction of a simple, fast program which stores code snippets. I have been using a local wiki up to now, but I find it a little annoying at times. Ideally I would like this application to be portable - i.e. it could run off of a USB stick on multiple machines with no installation. What do you guys use? EDIT: I would prefer a solution that was decoupled from the IDE and stored locally, not in the cloud. EDIT 2: Thanks for all the replies thus far, but I am still awaiting a non cloud / web based portable solution. Anyone else care to weigh in? :)

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• django url tag performance

  - by zxygentoo

  I was trying to integrate django-voting into my project following the RedditStyleVoting instruction. In my urls.py, i did something like this: url(r'^sections/(?P<object_id>\d+)/(?P<direction>up|down|clear)vote/?$', vote_on_object, dict( model=Section, template_object_name='section', template_name='script/section_confirm_vote.html', allow_xmlhttprequest=True ), name="section_vote", then, in my template: {% vote_by_user user on section as vote %} {% score_for_object section as score %} {% vote_by_user user on section as vote %} {% score_for_object section as score %} {{ score.score|default:0 }} It takes over 1.3s to load the page, but by hard coding it like this: {% vote_by_user user on section as vote %} {% score_for_object section as score %} {{ score.score|default:0 }} I got 50ms. Just avoid the url tag resolving stuff I got a 20+ times performance improvement. Is there something I did wrong? If not, then what's the best practice here, should we do things the right way or the fast way?

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• Advanced queries in HBase

  - by Teflon Ted

  Given the following HBase schema scenario (from the official FAQ)... How would you design an Hbase table for many-to-many association between two entities, for example Student and Course? I would define two tables: Student: student id student data (name, address, ...) courses (use course ids as column qualifiers here) Course: course id course data (name, syllabus, ...) students (use student ids as column qualifiers here) This schema gives you fast access to the queries, show all classes for a student (student table, courses family), or all students for a class (courses table, students family). How would you satisfy the request: "Give me all the students that share at least two courses in common"? Can you build a "query" in HBase that will return that set, or do you have to retrieve all the pertinent data and crunch it yourself in code?

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• Is it hard problem?

  - by Lukasz Lew

  I can't solve it: You are given 8 integers: A, B, C representing a line on a plane with equation A*x + B*y = C a, b, c representing another line x, y representing a point on a plane The two lines are not parallel therefore divide plane into 4 pieces. Point (x, y) lies inside of one these pieces. Problem: Write a fast algorithm that will find a point with integer coordinates in the same piece as (x,y) that is closest to the cross point of the two given lines. Note: This is not a homework, this is old Euler-type task that I have absolutely no idea how to approach.

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• How do you make Python wait so that you can read the output?

  - by anonnoir

  I've always been a heavy user of Notepad2, as it is fast, feature-rich, and supports syntax highlighting. Recently I've been using it for Python. My problem: when I finish editing a certain Python source code, and try to launch it, the screen disappears before I can see the output pop up. Is there any way for me to make the results wait so that I can read it, short of using an input() or time-delay function? Otherwise I'd have to use IDLE, because of the output that stops for you to read. (My apologies if this question is a silly one, but I'm very new at Python and programming in general.)

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• How to store and compare time-zone sensitive times

  - by Chad Moran

  I have a data structure where an entity has times stored as an int (minutes into the day) for fast comparison. The entity also has a Foreign Key reference back to a TimeZone table which contains the .NET CLR ID Name and it's Standard Time/Daylight Time acronyms. Since this information is stored as time-zone insensitive - I was wondering how in LINQ to SQL I could convert this into a UTC DateTime for comparison against other times that will be in UTC. Just to be clear this conversion has to be done server-side so that I can execute filtering on the SQL Server and not the client. I am using .NET 3.5 SP1 and SQL Server 2008.

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• Teaching a kid to type in order to start programming

  - by at

  My 5 year old wants to start programming, but he doesn't yet know how to type without looking for each letter 1 at a time. I know it's going to frustrate him to go so slow because of his typing speed. And it's not going to be fun looking for all the letters constantly... So what's the best way to get him to type fast? Clearly he'll need to type a lot of punctuation like semicolons, colons and symbols. So his little hands will have to get used to spreading over the keyboard... I did some google searches and found some very poor looking apps that focused on the letters.

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• How to config Remote BLOB Storage(RBS) with Microsoft Dynamics CRM 4.0 ?

  - by jk

  Hi We have working site for Dynamic crm 4.0 and in it we are storing image into the database. Now database is growing very fast and server is dying.. now I want to enable the Remote BLOB Storage with Dynamic CRM 4.0. for that I tried to install RBS for testing but everywhere is configure with Sharepoint 2010 not with Dynamic Crm. Does anybody know how to install and configure with Dyanmic CRM 4.0? Does RBS with Standard Edition of SQL Server 2008? I followed following path to install but it with Sharepoint? http://technet.microsoft.com/en-us/library/ee663474.aspx Any help is appreciate. Thanks

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