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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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  • 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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  • 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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  • What ever happened to APL?

    - by lkessler
    When I was at University 30 years ago, I used a programming language called APL. I believe the acronym stood for "A Programming Language", This language was interpretive and was especially useful for array and matrix operations with powerful operators and library functions to help with that. Did you use APL? Is this language still in use anywhere? Is it still available, either commercially or open source? I remember the combinatorics assignment we had. It was complex. It took a week of work for people to program it in PL/1 and those programs ranged from 500 to 1000 lines long. I wrote it in APL in under an hour. I left it at 10 lines for readability, although I should have been a purist and worked another hour to get it into 1 line. The PL/1 programs took 1 or 2 minutes to run on the IBM mainframe and solve the problem. The computer charge was $20. My APL program took 2 hours to run and the charge was $1,500 which was paid for by our Computer Science Department's budget. That's when I realized that a week of my time is worth way more than saving some $'s in someone else's budget. I got an A+ in the course. p.s. Don't miss this presentation entitled: "APL one of the greatest programming languages ever"

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  • Force CloudFront distribution/file update

    - by Martin
    I'm using Amazon's CloudFront to serve static files of my web apps. Is there no way to tell a cloudfront distribution that it needs to refresh it's file or point out a single file that should be refreshed? Amazon recommend that you version your files like logo_1.gif, logo_2.gif and so on as a workaround for this problem but that seems like a pretty stupid solution. Is there absolutely no other way?

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  • Industry-style practices for increasing productivity in a small scientific environment

    - by drachenfels
    Hi, I work in a small, independent scientific lab in a university in the United States, and it has come to my notice that, compared with a lot of practices that are ostensibly followed in the industry, like daily checkout into a version control system, use of a single IDE/editor for all languages (like emacs), etc, we follow rather shoddy programming practices. So, I was thinking of getting together all my programs, scripts, etc, and building a streamlined environment to increase productivity. I'd like suggestions from people on Stack Overflow for the same. Here is my primary plan.: I use MATLAB, C and Python scripts, and I'd like to edit, compile them from a single editor, and ensure correct version control. (questions/things for which I'd like suggestions are in italics) 1] Install Cygwin, and get it to work well with Windows so I can use git or a similar version control system (is there a DVCS which can work directly from the windows CLI, so I can skip the Cygwin step?). 2] Set up emacs to work with C, Python, and MATLAB files, so I can edit and compile all three at once from a single editor (say, emacs) (I'm not very familiar with the emacs menu, but is there a way to set the path to the compiler for certain languages? I know I can Google this, but emacs documentation has proved very hard for me to read so far, so I'd appreciate it if someone told me in simple language) 3] Start checking in code at the end of each day or half-day so as to maintain a proper path of progress of my code (two questions), can you checkout files directly from emacs? is there a way to checkout LabVIEW files into a DVCS like git? Lastly, I'd like to apologize for the rather vague nature of the question, and hope I shall learn to ask better questions over time. I'd appreciate it if people gave their suggestions, though, and point to any resources which may help me learn.

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  • Which number of processes will give me the best performance ?

    - by Maarten
    I am doing some expensive caluations right now. It is one programm, which I run several instances of at the same time. I am running them under linux on a machine with 4 cpus with 6 cores each. The cpus are Intel Xeon X5660, which support hyper thearting. (That's some insane hardware, huh?) Right now I am running 24 processes at once. Would it be better to run more, b/c of HT ?

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  • Writing fortran robust and "modern" code

    - by Blklight
    In some scientific environments, you often cannot go without FORTRAN as most of the developers only know that idiom, and there is lot of legacy code and related experience. And frankly, there are not many other cross-platform options for high performance programming ( C++ would do the task, but the syntax, zero-starting arrays, and pointers are too much for most engineers ;-) ). I'm a C++ guy but I'm stuck with some F90 projects. So, let's assume a new project must use FORTRAN (F90), but I want to build the most modern software architecture out of it. while being compatible with most "recent" compilers (intel ifort, but also including sun/HP/IBM own compilers) So I'm thinking of imposing: global variable forbidden, no gotos, no jump labels, "implicit none", etc. "object-oriented programming" (modules with datatypes + related subroutines) modular/reusable functions, well documented, reusable libraries assertions/preconditions/invariants (implemented using preprocessor statements) unit tests for all (most) subroutines and "objects" an intense "debug mode" (#ifdef DEBUG) with more checks and all possible Intel compiler checks possible (array bounds, subroutine interfaces, etc.) uniform and enforced legible coding style, using code processing tools C stubs/wrappers for libpthread, libDL (and eventually GPU kernels, etc.) C/C++ implementation of utility functions (strings, file operations, sockets, memory alloc/dealloc reference counting for debug mode, etc.) ( This may all seem "evident" modern programming assumptions, but in a legacy fortran world, most of these are big changes in the typical programmer workflow ) The goal with all that is to have trustworthy, maintainable and modular code. Whereas, in typical fortran, modularity is often not a primary goal, and code is trustworthy only if the original developer was very clever, and the code was not changed since then ! (i'm a bit joking here, but not much) I searched around for references about object-oriented fortran, programming-by-contract (assertions/preconditions/etc.), and found only ugly and outdated documents, syntaxes and papers done by people with no large-scale project involvement, and dead projects. Any good URL, advice, reference paper/books on the subject?

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  • What are programming lost arts?

    - by pavpanchekha
    Have you ever programmed raw machine code (not for class)? Examined a hex dump with just a hex editor (or, heck, without)? Written your own software floating-point library? Division library? Written a non-school-assignment in Lisp or Forth? What sort of "lost arts" have been forgotten? And what reason (if any) would there be to resurrect them?

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  • How to Profile R Code that Includes SNOW Cluster

    - by James
    Hi, I have a nested loop that I'm using foreach, DoSNOW, and a SNOW socket cluster to solve for. How should I go about profiling the code to make sure I'm not doing something grossly inefficient. Also is there anyway to measure the data flows going between the master and nodes in a Snow cluster? Thanks, James

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  • Should I persist images on EBS or S3?

    - by javanes
    I am migrating my Java,Tomcat, Mysql server to AWS EC2. I have already attached EBS volume for storing MySql data. In my web application people may upload images. So I should persist them. There are 2 alternatives in my mind: Save uploaded images to EBS volume. Use the S3 service. The followings are my notes, please be skeptic about them, as my expertise is not on servers, but software development. EBS plus: S3 storage is more expensive. (0.15 $/Gb 0.1$/Gb) S3 plus: Serving statics from EBS may influence my web server's performance negatively. Is this true? Does Serving images affect server performance notably? For S3 my server will not be responsible for serving statics. S3 plus: Serving statics from EBS may result I/O cost, probably it will be minor. EBS plus: People say EBS is faster. S3 plus: People say S3 is more safe for persistence. EBS plus: No need to learn API, it is straight forward to save the images to EBS volume. Namely I can not decide, will be happy if you guide. Thanks

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  • Gluster strange issue with shared mount point like seprate mount.

    - by Satish
    I have two nodes and for experiment i have install glusterfs and create volume and successfully mounted on own node, but if i create file in node1 it is not showing in node2, look like both behaving like they are separate. node1 10.101.140.10:/nova-gluster-vol 2.0G 820M 1.2G 41% /mnt node2 10.101.140.10:/nova-gluster-vol 2.0G 33M 2.0G 2% /mnt volume info split brian $ sudo gluster volume heal nova-gluster-vol info split-brain Gathering Heal info on volume nova-gluster-vol has been successful Brick 10.101.140.10:/brick1/sdb Number of entries: 0 Brick 10.101.140.20:/brick1/sdb Number of entries: 0 test node1 $ echo "TEST" > /mnt/node1 $ ls -l /mnt/node1 -rw-r--r-- 1 root root 5 Oct 27 17:47 /mnt/node1 node2 (file isn't there, while they are shared mount) $ ls -l /mnt/node1 ls: cannot access /mnt/node1: No such file or directory What i am missing??

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  • Build farms using ccnet

    - by Grzenio
    Is it possible to use CruiseControl.Net to set up a build farm? We currently have 4 different build machines building different things at different times and have a bit of a headache to manually balance the load somehow. I would prefer to designate one of them to be the master build machine, which would delegate work to the other ones when they are free.

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  • Distributed Message Ordering

    - by sbanwart
    I have an architectural question on handling message ordering. For purposes of this question, the transport is irrelevant, so I'm not going to specify one. Say we have three systems, a website, a CRM and an ERP. For this example, the ERP will be the "master" system in terms of data ownership. The website and the CRM can both send a new customer message to the ERP system. The ERP system then adds a customer and publishes the customer with the newly assigned account number so that the website and CRM can add the account number to their local customer records. This is a pretty straight forward process. Next we move on to placing orders. The account number is required in order for the CRM or website to place an order with the ERP system. However the CRM will permit the user to place an order even if the customer lacks an account number. (For this example assume we can't modify the CRM behavior) This creates the possibility that a user could create a new customer, and place an order before the account number gets updated in the CRM. What is the best way to handle this scenario? Would it be best to send the order message sans account number and let it go to an error queue? Would it be better to have the CRM endpoint hold the message and wait until the account number is updated in the CRM? Maybe something completely different that I haven't thought of? Thanks in advance for any help.

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  • cloud and existing enterprise applications technologies

    - by maxxxee
    What is the significance of new cloud platforms and databases like Microsoft Azure and Amazon EC2? Is it a replacement for enterprise application platforms like .net or JEE in a cloud environment? Is it neccessary to use these or other cloud specific platforms, or can we implement .net or JEE on a cloud based environment?

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  • Cloud Database Service Latency/Performance

    - by Gcoop
    Hi All, I am running a heavy traffic site and our server is beginning to get to its limits, at the moment the entire LAMP stack is on one box (not ideal). I would like to move the database onto it's own box or onto a cloud service, but from my previous experience moving the database off the same box as the webserver increases the latency of reads quite dramatically slowing down the site. Is using a cloud service for this going to overcome this problem, because as far as I can tell its essentially the same situation (as moving it onto a separate box in my control)? In which case why is there so much popularity around cloud based database services at the moment? Are cloud based database services so quick that the latency of reads is so low that its almost like having it on the same box in the same datacentre?

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