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  • Fastest Strategy for Drawing Flash Particles

    - by user146543
    I am wondering what the fastest approach might be for using Flash/AS3 to render a 2D point plot (sonar lofargram) ; basically screens full of tiny 2D dots using Flash as fast as possible. Any suggestions on where to start? Is Flash capable of displaying 10's of thousands of 2D points (or more) with an acceptable fps?

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  • Hadoop safemode recovery - taking lot of time

    - by Algorist
    Hi, We are running our cluster on Amazon EC2. we are using cloudera scripts to setup hadoop. On the master node, we start below services. 609 $AS_HADOOP '"$HADOOP_HOME"/bin/hadoop-daemon.sh start namenode' 610 $AS_HADOOP '"$HADOOP_HOME"/bin/hadoop-daemon.sh start secondarynamenode' 611 $AS_HADOOP '"$HADOOP_HOME"/bin/hadoop-daemon.sh start jobtracker' 612 613 $AS_HADOOP '"$HADOOP_HOME"/bin/hadoop dfsadmin -safemode wait' On the slave machine, we run the below services. 625 $AS_HADOOP '"$HADOOP_HOME"/bin/hadoop-daemon.sh start datanode' 626 $AS_HADOOP '"$HADOOP_HOME"/bin/hadoop-daemon.sh start tasktracker' The main problem we are facing is, hdfs safemode recovery is taking more than an hour and this is causing delays in our job completion. Below are the main log messages. 1. domU-12-31-39-0A-34-61.compute-1.internal 10/05/05 20:44:19 INFO ipc.Client: Retrying connect to server: ec2-184-73-64-64.compute-1.amazonaws.com/10.192.11.240:8020. Already tried 21 time(s). 2. The reported blocks 283634 needs additional 322258 blocks to reach the threshold 0.9990 of total blocks 606499. Safe mode will be turned off automatically. The first message is thrown in task trackers log because, job tracker is not started. job tracker didn't start because of hdfs safemode recovery. The second message is thrown during the recovery process. Is there something I am doing wrong? How much time does normal hdfs safemode recovery takes? Will there be any speedup, by not starting task trackers till job tracker is started? Are there any known hadoop problems on amazon cluster? Thanks for your help. Regards Bala Mudiam

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  • Jini : single server with multiple clients

    - by user200340
    Hi all, I have a question about how to make multiple clients can access a single file located on server side and keep the file consistent. I have a simple PhoneBook server-client Jini program running at the moment, and server only provides some getter functions to clients, such as getName(String number), getNumber(String name) from a PhoneBook class(serializable), phonebook data are stored in a text file (phonebook.txt) at the moment. I have tried to implement some functions allowing to write a new records into the phonebook.txt file. If the writing record (name) is existing, an integer number will be added into the writing record. for example the existing phonebook.txt is .... John 01-01010101 .... if the writing record is "John 01-12345678",then "John_1 01-12345678" will be writen into phonebook.txt However, if i start with two clients A and B (on the same machine using localhost), and A tries to write "John 01-11111111", B tries to write "John 01-22222222". The early record will be overwritten later record. So, there must be something i did complete wrong. My client and server code are just like Jini HelloWorld example. My server side code is . 1. LookupDiscovery with parameter new String[]{""}; 2. DiscoveryListener for LookupDiscovery 3. registrations are saved into a HashTable 4. for every discovered lookup service, i use registrar to register the ServiceItem, ServiceItem contains a null attributeSets, a null serviceId, and a service. The client code has: 1. LookupDiscovery with parameter new String[]{""}; 2. DiscoveryListener for LookupDiscovery 3. a ServiceTemplate with null attributeSets, a null serviceId and a type, the type is the interface class. 4. for each found ServiceRegistrar, if it can find the looking for ServiceTemplate, the returned Object is cast into the type of the interface class. I have tried to google more details, and i found JavaSpace could be the one i missed. But i am still not sure about it (i only start Jini for a very short time). So any help would be greatly appreciated.

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  • Python's FTPLib too slow ?

    - by PyNEwbie
    I have been playing around with Python's FTP library and am starting to think that it is too slow as compared to using a script file in DOS? I run sessions where I download thousands of data files (I think I have over 8 million right now). My observation is that the download process seems to take five to ten times as long in Python than it does as compared to using the ftp commands in the DOS shell. Since I don't want anyone to fix my code I have not included any. I am more interested in understanding if my observation is valid or if I need to tinker more with the arguments.

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  • Open source alternative to MATLAB's fmincon function?

    - by dF
    Is there an open-source alternative to MATLAB's fmincon function for constrained linear optimization? I'm rewriting a MATLAB program to use Python / NumPy / SciPy and this is the only function I haven't found an equivalent to. A NumPy-based solution would be ideal, but any language will do.

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  • Dashboard for collaborative science / data processing projects

    - by rescdsk
    Hi, Continuous Integration servers like Hudson are a pretty amazing addition to software development. I work in an academic research lab, and I'd love to apply similar principles to scientific data analysis. I want a dashboard-like view of which collections of data are fine, which ones are failing their tests (simple shell scripts, mostly), and so on. A lot like the Chromium dashboard (WARNING: page takes a long time to load). It takes work from at least 4 people, and maybe 10 or 12 hours of computer time, to bring our data (from behavioral studies) from its raw form to its final, easily-analyzed form. I've tried Hudson and buildbot, but neither is really appropriate to our workflow. We just want to run a bunch of tests on maybe fifty independent collections of subject data, and display the results nicely. SO! Does anyone have a recommendation of a way to generate this kind of report easily? Or, can you think of a good way to shoehorn this kind of workflow into a continuous integration server? Or, can you recommend a unit testing dashboard that could deal with tests that are little shell scripts rather than little functions? Thank you!

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  • Best cubicle toys for programming

    - by dlamblin
    I need some employee/co-worker Christmas gift ideas. Do you have any good cubicle toys that help you to do any of: think about programming problems solve programming problems by representing common abstractions can be directly programmed can interface with a PC based IDE to be programmed. it may present problems that can be solved, to kick start problem solving. Disallowed items are: reference material in book, pamphlet, poster or cheat-sheet form, even if it has kick ass pop-cultural references. edibles. [discuss separately] things that need their own lab-space and/or extensive tools to be worked with. So yes, Lego Mindstorms come to mind, but they aren't cubicle toys because they cost more than cubicle toys would, and they have too many losable parts. comments on the answers so far: The 20 Questions game sounds quite neat as it could get you thinking; The bean balls could be used as tokens in a problem, so I can see that working. The magnetic toys like ball of whacks or the ball-and-stick ones present hands on fun of a structural nature... now can there be a similar hands on fun toy that aids in representing a solution to a problem? The Gui Mags clearly could, but they're quite utility oriented. The AVR Butterfly is less of a toy but definitely priced attractively, cheaper and more responsive than a basic stamp. I'm not going to pick an answer; there's several great suggestions here. Thank you.

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  • Software tools for allowing end users to reprogram interfaces

    - by iceman
    What would be the examples of commercial software products (specially web-services) which allow the end user to reprogram their user-interface? I mean end users who do not know programming and they are allowed to add more functionality. One way of doing it is allowing XML gadgets like iGoogle does. What are the other approaches and also the technologies enabling them? This would be a futuristic application like collaborative software development for users.

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  • Hadooop map reduce

    - by Aina Ari
    Im very much new to map reduce and i completed hadoop wordcount example. In that example it produces unsorted file (with key value) of word counts. So is it possible to make it sorted according to the most number of word occurrences by combining another map reduce task to the earlier one. Thanks in Advance

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  • Draw on screen border in Commodore 64

    - by Stefano Borini
    Ok. I hope it does not get closed because I have this curiosity since 25 years and I would love to understand the trick. In the commodore 64 the border was not addressable by the 6569 VIC. All you could do was to draw pixels in the central area, the one where the cursor moved. The border was always uniform, although you could change its color with poke 53280,color if i remember correctly. Nevertheless I clearly remember games intros where the border was featured with graphics, like it was fully addressable. I tried to understand how it worked but never got to the point. legends say it was a clever use of sprites, which could, under some circumstances, be drawn on the border, but I don't know if it's an urban legend. edit: just read this from one of the provided links Sprites were multiplexed across vertical raster lines (over 8 sprites, sometimes up to 120 sprites). Until the Group Crest released Krestage 3 in May 2007 there was the common perception that no more than 8 sprites could appear at one raster line, but assigning new Y coordinates made it reappear further down the screen. This is evil.... you beat the raster and reposition the sprite before it gets there...

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  • 404 redirect with cloud storage

    - by Jeremy DeGroot
    I'm hoping to reach someone with some experience using a service like Amazon's S3 with this question. On my site we have a dedicated image server. And on this server, we have an automatic 404 redirect through Apapche so that, if a user tries to access an image that doesn't exist, they'll see a snazzy "Image Not Available" image. We're looking to move the hosting of these images to a cloud storage solution (S3 or Rackspace's CloudFiles), and I'm wondering if anyone's had any success replicating this behavior on a cloud storage service and if so how they did it.

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  • Linux HA / cluster: what are the differences between Pacemaker, Heartbeat, Corosync, wackamole?

    - by Continuation
    Can you help me understand Linux HA? Pacemaker, Heartbeat, Corosync seem to be part of a whole HA stack, but how do they fit together? How does wackamole differ from Pacemaker/Heartbeat/Corosync? I've seen opinions that wackamole is better than Heartbeat because it's peer-based. Is that valid? The last release of wackamole was 2.5 years ago. Is it still being maintained or active? What would you recommend for HA setup for web/application/database servers?

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  • Python if statement efficiency

    - by Dennis
    A friend (fellow low skill level recreational python scripter) asked me to look over some code. I noticed that he had 7 separate statements that basically said. if ( a and b and c): do something the statements a,b,c all tested their equality or lack of to set values. As I looked at it I found that because of the nature of the tests, I could re-write the whole logic block into 2 branches that never went more than 3 deep and rarely got past the first level (making the most rare occurrence test out first). if a: if b: if c: else: if c: else: if b: if c: else: if c: To me, logically it seems like it should be faster if you are making less, simpler tests that fail faster and move on. My real questions are 1) When I say if and else, should the if be true, does the else get completely ignored? 2) In theory would if (a and b and c) take as much time as the three separate if statements would?

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  • Any Open Source Pregel like framework for distributed processing of large Graphs?

    - by Akshay Bhat
    Google has described a novel framework for distributed processing on Massive Graphs. http://portal.acm.org/citation.cfm?id=1582716.1582723 I wanted to know if similar to Hadoop (Map-Reduce) are there any open source implementations of this framework? I am actually in process of writing a Pseudo distributed one using python and multiprocessing module and thus wanted to know if someone else has also tried implementing it. Since public information about this framework is extremely scarce. (A link above and a blog post at Google Research)

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  • Simple html vs Javascript generated html?

    - by Rizo
    In my web application I would like to complately avoid html and use only javascript to create web-page's dom tree. What is faster writing web content in the traditional way in html <div>Some text</div> or using javascript dom render, like this: div.appendChild(document.createTextNode("Some text"));?

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  • Retro video games programming

    - by SebKom
    I just watched the Super Mario Bros. -1 World glitch in youtube and I really began wondering about the code behind those games. Which language was used? What about the OS for the video games consoles? Are there any website with resources about this subject? (I am a 90s video gamer so I am particularly interested about the programming behind those games but feel free to make this a wiki and include links to resources about video games programming in general, if you want)

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  • Where can I get resources for developing for Mac OS Classic?

    - by Benjamin Pollack
    I recently got bored and fired up my old Mac OS Classic emulator, and then got nostalgic for writing old-school applications for the system. So, my question: Where can I get dev tools that can still target Classic? (Ideally free, since this is just for fun, but if grabbing a used version of CodeWarrior on eBay is the best way to go, so be it.) Where can I get at least reference materials so I don't have to guess-and-check my way around Carbon/the System Toolbox? Are there any forums still running that would be open to answering old-school Mac questions for when I get stuck? This is purely for fun, so don't worry about how impractical this is. I know.

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  • Problem with copying local data onto HDFS on a Hadoop cluster using Amazon EC2/ S3.

    - by Deepak Konidena
    Hi, I have setup a Hadoop cluster containing 5 nodes on Amazon EC2. Now, when i login into the Master node and submit the following command bin/hadoop jar <program>.jar <arg1> <arg2> <path/to/input/file/on/S3> It throws the following errors (not at the same time.) The first error is thrown when i don't replace the slashes with '%2F' and the second is thrown when i replace them with '%2F': 1) Java.lang.IllegalArgumentException: Invalid hostname in URI S3://<ID>:<SECRETKEY>@<BUCKET>/<path-to-inputfile> 2) org.apache.hadoop.fs.S3.S3Exception: org.jets3t.service.S3ServiceException: S3 PUT failed for '/' XML Error Message: The request signature we calculated does not match the signature you provided. check your key and signing method. Note: 1)when i submitted jps to see what tasks were running on the Master, it just showed 1116 NameNode 1699 Jps 1180 JobTracker leaving DataNode and TaskTracker. 2)My Secret key contains two '/' (forward slashes). And i replace them with '%2F' in the S3 URI. PS: The program runs fine on EC2 when run on a single node. Its only when i launch a cluster, i run into issues related to copying data to/from S3 from/to HDFS. And, what does distcp do? Do i need to distribute the data even after i copy the data from S3 to HDFS?(I thought, HDFS took care of that internally) IF you could direct me to a link that explains running Map/reduce programs on a hadoop cluster using Amazon EC2/S3. That would be great. Regards, Deepak.

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  • Am I "wasting" my time learning C and other low level stuff ?

    - by Andreas Grech
    I have just recently started learning C and the reason I did that was because frankly, I consider myself to be of a "less-developer" than the people who know and work with C. Thus I planned to start learning ASM, C, C++ and bought the K&R book and started pushing myself to learn the C Programming Language and up till now I'm doing great...learning about arrays the low level way (ie the pointer + offset thing), pointers and all that and obviously asking questions on stackoverflow for guidance. My problem is that sometimes I get thinking if instead of learning this low level stuff, maybe I should maybe spend more time learning newer, more widely used technologies...basically, more web stuff. Now I am well versed with both C# and ASP.Net and currently that's what I do for a living, but still there exists Microsoft technologies that I haven't quite touched upon...such as ASP.Net MVC, The Entity Framework etc... And those are only Microsoft Technologies...obviously there are other stuff that I would like to touch upon...stuff like Ruby, which would lead me to Ruby on Rails, or Python for Django or even Java and J2EE, or maybe even PHP; ie, basically mainly Web Stuff. Mind you, I did touch upon some of the stuff I mentioned earlier on, such as PHP and Java but I am still not quite versed in them as I am in C# and ASP.Net...but still, I think that by learning other languages that are used in the web environment will broaden my horizons...both as a developer who loves learning, and also Career wise. My point is, am I really using up my time correctly by learning older, lower level stuff? Stuff that for my current line of work, will most probably never use, but still is interesting to know ? To be frankly honest, I am also learning C so that I could, maybe someday, get into Electronics and Micro-controller programming but that is a whole new world for me and, if I choose to go there, will take some time to get adjusted to. And even then, I don't know if I can get a career in working in that line of work. ...but I still wonder about this question over and over...Am I doing the right thing by learning C instead of something (Web-stuff) that will most probably be more useful for me career-wise? I'm sorry for such asking such a long and most probably a boring question, but I feel as if this is the only place where I can ask such a question and get an honest answer from experts in the field. Thank you for your time.

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  • Better to build or buy a compute grid platform?

    - by James B
    I am looking to do some quite processor-intensive brute force processing for string matching. I have run my prototype in a multi-threaded environment and compared the performance to an implementation using Gridgain with a couple of nodes (also multithreaded). The performance I observed was that my Gridgain implementation performed slower to my multithreaded implementation. It could be the case that there was a flaw in my gridgain implementation, but it was only a prototype, and I thought the results were indicative. So my question is this: What are the advantages of having to learn and then build an implementation for a particular grid platform (hadoop, gridgain, or EC2 if going hosted - other suggestions welcome), when one could fairly easily put together a lightweight compute grid platform with a much shallower learning curve?...i.e. what do we get for free with these cloud/grid platforms that are worth having/tricky to implement? (Please note, I don't have any need for a data grid) Cheers, -James (p.s. Happy to make this community wiki if needbe)

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  • A leader election algorithm for an oriented hypercube

    - by mick
    I'm stuck with some problem where I have to design a leader election algorithm for an oriented hypercube. This should be done by using a tournament with a number of rounds equal to the dimension D of the hypercube. In each stage d, with 1 <= d < D two candidate leaders of neighbouring d-dimensional hypercubes should compete to become the single candidate leader of the (d+1)-dimensional hypercube that is the union of their respective hypercubes.

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  • Sort algorithm with fewest number of operations

    - by luvieere
    What is the sort algorithm with fewest number of operations? I need to implement it in HLSL as part of a pixel shader effect v2.0 for WPF, so it needs to have a really small number of operations, considering Pixel Shader's limitations. I need to sort 9 values, specifically the current pixel and its neighbors.

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