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  • "Priming" a whole database in MSSQL for first-hit speed

    - by David Spillett
    For a particular apps I have a set of queries that I run each time the database has been restarted for any reason (server reboot usually). These "prime" SQL Server's page cache with the common core working set of the data so that the app is not unusually slow the first time a user logs in afterwards. One instance of the app is running on an over-specced arrangement where the SQL box has more RAM than the size of the database (4Gb in the machine, the DB is under 1.5Gb currently and unlikely to grow too much relative to that in the near future). Is there a neat/easy way of telling SQL Server to go away and load everything into RAM? It could be done the hard way by having a script scan sysobjects & sysindexes and running SELECT * FROM <table> WITH(INDEX(<index_name>)) ORDER BY <index_fields> for every key and index found, which should cause every used page to be read at least once and so be in RAM, but is there a cleaner or more efficient way? All planned instances where the database server is stopped are out-of-normal-working-hours (all the users are at most one timezone away and unlike me none of them work at silly hours) so such a process (until complete) slowing down users more than the working set not being primed at all would is not an issue.

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  • Project Euler problem 214, How can i make it more efficient?

    - by Once
    I am becoming more and more addicted to the Project Euler problems. However since one week I am stuck with the #214. Here is a short version of the problem: PHI() is Euler's totient function, i.e. for any given integer n, PHI(n)=numbers of k<=n for which gcd(k,n)=1. We can iterate PHI() to create a chain. For example starting from 18: PHI(18)=6 = PHI(6)=2 = PHI(2)=1. So starting from 18 we get a chain of length 4 (18,6,2,1) The problem is to calculate the sum of all primes less than 40e6 which generate a chain of length 25. I built a function that calculates the chain length of any number and I tested it for small values: it works well and fast. sum of all primes<=20 which generate a chain of length 4: 12 sum of all primes<=1000 which generate a chain of length 10: 39383 Unfortunately my algorithm doesn't scale well. When I apply it to the problem, it takes several hours to calculate... so I stop it because the Project Euler problems must be solved in less than one minute. I thought that my prime detection function might be slow so I fed the program with a list of primes <40e6 to avoid the primality test... The code runs now a little bit faster, but there is still no way to get a solution in less than a few hours (and I don't want this). So is there any "magic trick" that I am missing here ? I really don't understand how to be more efficient on this one... I am not asking for the solution, because fighting with optimization is all the fun of Project Euler. However, any small hint that could put me on the right track would be welcome. Thanks !

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  • How to "reduce" a hash?

    - by Julien Lebosquain
    Suppose I have any "long" hash, like a 16 bytes MD5 or a 20 bytes SHA1. I want to reduce this hash to fit on 4 bytes, for GetHashCode() purposes. First, I'm perfectly aware that I'll get more collisions. That's totally fine in my case, but I'd still prefer to get the less possible collisions. There are several solutions to my problem: I could take the 4 first bytes of the hash. I could take the 4 last bytes of the hash. I could take 4 random bytes of the hash. I could generate a hash of the hash, involving classic prime numbers multiplications. Are there other solutons I didn't think about? And more importantly, what method will give me the most unique hash code? I'm currently supposing they're almost equivalent. Microsoft choose that the public key token of an assembly is the last 8 bytes of the SHA1 hash of its public key, so I'll probably go for this solution but I'd like to know why.

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  • Project Euler, Problem 10 java solution not working

    - by Dennis S
    Hi, I'm trying to find the sum of the prime numbers < 2'000'000. This is my solution in java but I can't seem get the correct answer. Please give some input on what could be wrong and general advice on the code is appreciated. Printing 'sum' gives: 1308111344, which is incorrect. /* The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million. */ class Helper{ public void run(){ Integer sum = 0; for(int i = 2; i < 2000000; i++){ if(isPrime(i)) sum += i; } System.out.println(sum); } private boolean isPrime(int nr){ if(nr == 2) return true; else if(nr == 1) return false; if(nr % 2 == 0) return false; for(int i = 3; i < Math.sqrt(nr); i += 2){ if(nr % i == 0) return false; } return true; } } class Problem{ public static void main(String[] args){ Helper p = new Helper(); p.run(); } }

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  • Javascript CS-PRNG - 64-bit random

    - by Jack
    Hi, I need to generate a cryptographically secure 64-bit unsigned random integer in Javascript. The first problem is that Javascript only allows 64-bit signed integers, so 9223372036854775808 is the biggest supported integer without going into floating point use I think? To fix this I can use a big number library, no problem. My Method: var randNum = SHA256( randBigInt(128, 0) ) % 2^64; Where SHA256() is a secure hash function and randBigInt() is defined below as a non-crypto PRNG, im giving it a 128bit seed so brute force shouldn't be a problem. randBigInt(n,s) //return an n-bit random BigInt (n>=1). If s=1, then the most significant of those n bits is set to 1. Is this a secure method to generate a cryptographically secure 64-bit random int? And importantly does taking the 2^64 mod guarantee 100% I have a 64-bit number? An abstract example, say this number is prime (it isn't i know), I will use it in the Galois Field [2^p], where p must be 64bits so that every possible 1-63bit number is a field element. In this query, my random int must be larger than any 63-bit number. And Im not sure im correct in taking the 2^64 mod of a 256bit hash output. Thanks (hope that makes sense)

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  • Why isn't my submit button centered?

    - by William
    For some reason my submit button isn't centered. http://prime.programming-designs.com/test_forum/viewboard.php?board=0 #submitbutton{ margin: auto; border: 1px solid #DBFEF8; background-color: #DBFEF8; color: #000000; margin-top: 5px; width: 100px; height: 20px; } here's the html. <form method=post action=add_thread.php?board=<?php echo''.$board.''; ?>> <div id="formdiv"> <div class="fieldtext1">Name</div> <div class="fieldtext1">Trip</div> <input type="text" name=name size=25 /> <input type="text" name=trip size=25 /> <div class="fieldtext2">Comment</div> <textarea name=post rows="4" cols="70"></textarea> <div class="fieldtext2">Fortune</div> <input type="checkbox" name="fortune" value="fortune" /> </div> <input type=submit value="Submit" id="submitbutton"> </form>

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  • SVG rotation animation having problems on chrome for jelly bean, is there a workaround?

    - by Metalskin
    I've got a strange problem with chrome on jellybean running svg animations triggered from javascript. This JSFiddle example works fine on chrome and firefox on linux, but when I run it on android with chrome I get the final step of the animation painted at the beginning of the animation. I've tried this on both an Nexus 7 and Transformer Prime, they both have the problem. I've tested using firefox on the android devices and the problem doesn't exist. So I'm presuming that it's a defect with chrome. However I've seen other animations using svg that do not have this problem in chrome on jellybean. Is anyone aware of a way to get around this problem, or is there something that I'm doing in my animation/js that is a possible cause of the problem? I've now created a bug report at code.google.com, however I still need a workaround, if anyone can help me (or in case I'm doing something stupid). I've now discovered that this is reproducible on chrome for linux (and I suspect windows). If you click on the button to start the animation before the previous animation has completed then the problem occurs. In this case the hand is drawn at the end of the 45 degree sweep before it starts the sweep. I now suspect that I should be calling something to stop the animation before I change the animation. Anyway, hopefully someone can resolve this problem.

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  • Problem with Boost::Asio for C++

    - by Martin Lauridsen
    Hi there, For my bachelors thesis, I am implementing a distributed version of an algorithm for factoring large integers (finding the prime factorisation). This has applications in e.g. security of the RSA cryptosystem. My vision is, that clients (linux or windows) will download an application and compute some numbers (these are independant, thus suited for parallelization). The numbers (not found very often), will be sent to a master server, to collect these numbers. Once enough numbers have been collected by the master server, it will do the rest of the computation, which cannot be easily parallelized. Anyhow, to the technicalities. I was thinking to use Boost::Asio to do a socket client/server implementation, for the clients communication with the master server. Since I want to compile for both linux and windows, I thought windows would be as good a place to start as any. So I downloaded the Boost library and compiled it, as it said on the Boost Getting Started page: bootstrap .\bjam It all compiled just fine. Then I try to compile one of the tutorial examples, client.cpp, from Asio, found (here.. edit: cant post link because of restrictions). I am using the Visual C++ compiler from Microsoft Visual Studio 2008, like this: cl /EHsc /I D:\Downloads\boost_1_42_0 client.cpp But I get this error: /out:client.exe client.obj LINK : fatal error LNK1104: cannot open file 'libboost_system-vc90-mt-s-1_42.lib' Anyone have any idea what could be wrong, or how I could move forward? I have been trying pretty much all week, to get a simple client/server socket program for c++ working, but with no luck. Serious frustration kicking in. Thank you in advance.

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  • Questions about the Backpropogation Algorithm

    - by Colemangrill
    I have a few questions concerning backpropogation. I'm trying to learn the fundamentals behind neural network theory and wanted to start small, building a simple XOR classifier. I've read a lot of articles and skimmed multiple textbooks - but I can't seem to teach this thing the pattern for XOR. Firstly, I am unclear about the learning model for backpropogation. Here is some pseudo-code to represent how I am trying to train the network. [Lets assume my network is setup properly (ie: multiple inputs connect to a hidden layer connect to an output layer and all wired up properly)]. SET guess = getNetworkOutput() // Note this is using a sigmoid activation function. SET error = desiredOutput - guess SET delta = learningConstant * error * sigmoidDerivative(guess) For Each Node in inputNodes For Each Weight in inputNodes[n] inputNodes[n].weight[j] += delta; // At this point, I am assuming the first layer has been trained. // Then I recurse a similar function over the hidden layer and output layer. // The prime difference being that it further divi's up the adjustment delta. I realize this is probably not enough to go off of, and I will gladly expound on any part of my implementation. Using the above algorithm, my neural network does get trained, kind of. But not properly. The output is always XOR 1 1 [smallest number] XOR 0 0 [largest number] XOR 1 0 [medium number] XOR 0 1 [medium number] I can never train the [1,1] [0,0] to be the same value. If you have any suggestions, additional resources, articles, blogs, etc for me to look at I am very interested in learning more about this topic. Thank you for your assistance, I appreciate it greatly!

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  • List of Big-O for PHP functions?

    - by Kendall Hopkins
    After using PHP for a while now, I've noticed that not all PHP built in functions as fast as expected. Consider the below two possible implementations of a function that finds if a number is prime using a cached array of primes. //very slow for large $prime_array $prime_array = array( 2, 3, 5, 7, 11, 13, .... 104729, ... ); $result_array = array(); foreach( $array_of_number => $number ) { $result_array[$number] = in_array( $number, $large_prime_array ); } //still decent performance for large $prime_array $prime_array => array( 2 => NULL, 3 => NULL, 5 => NULL, 7 => NULL, 11 => NULL, 13 => NULL, .... 104729 => NULL, ... ); foreach( $array_of_number => $number ) { $result_array[$number] = array_key_exists( $number, $large_prime_array ); } This is because in_array is implemented with a linear search O(n) which will linearly slow down as $prime_array grows. Where the array_key_exists function is implemented with a hash lookup O(1) which will not slow down unless the hash table gets extremely populated (in which case it's only O(logn)). So far I've had to discover the big-O's via trial and error, and occasionally looking at the source code. Now for the question... I was wondering if there was a list of the theoretical (or practical) big O times for all* the PHP built in functions. *or at least the interesting ones For example find it very hard to predict what the big O of functions listed because the possible implementation depends on unknown core data structures of PHP: array_merge, array_merge_recursive, array_reverse, array_intersect, array_combine, str_replace (with array inputs), etc.

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  • Project Euler, Problem 10 java solution now working

    - by Dennis S
    Hi, I'm trying to find the sum of the prime numbers < 2'000'000. This is my solution in java but I can't seem get the correct answer. Please give some input on what could be wrong and general advice on the code is appreciated. Printing 'sum' gives: 1308111344, which is incorrect. /* The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million. */ class Helper{ public void run(){ Integer sum = 0; for(int i = 2; i < 2000000; i++){ if(isPrime(i)) sum += i; } System.out.println(sum); } private boolean isPrime(int nr){ if(nr == 2) return true; else if(nr == 1) return false; if(nr % 2 == 0) return false; for(int i = 3; i < Math.sqrt(nr); i += 2){ if(nr % i == 0) return false; } return true; } } class Problem{ public static void main(String[] args){ Helper p = new Helper(); p.run(); } }

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  • Int - number too large. How to get program to fail?

    - by Dave
    Hi Problem: How do you get a program to fail if a number goes beyond the bounds of its type? This code below gives the wrong answer for sum of primes under 2 million as I'd used an int instead of a long. [TestMethod] public void CalculateTheSumOfPrimesBelow2million() { int result = PrimeTester.calculateTheSumOfPrimesBelow(2000000); // 2million Assert.AreEqual(1, result); // 1,179,908,154 .. this was what I got with an int... // correct answer was 142,913,828,922 with a long } public static class PrimeTester { public static int calculateTheSumOfPrimesBelow(int maxPrimeBelow) { // we know 2 is a prime number int sumOfPrimes = 2; int currentNumberBeingTested = 3; while (currentNumberBeingTested < maxPrimeBelow) { double squareRootOfNumberBeingTested = (double)Math.Sqrt(currentNumberBeingTested); bool isPrime = true; for (int i = 2; i <= squareRootOfNumberBeingTested; i++) { if (currentNumberBeingTested % i == 0) { isPrime = false; break; } } if (isPrime) sumOfPrimes += currentNumberBeingTested; currentNumberBeingTested += 2; // as we don't want to test even numbers } return sumOfPrimes; } }

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  • Why is my php script freezing?

    - by William
    What is causing my php code to freeze? I know it's cause of the while loop, but I have $max_threads--; at the end so it shouldn't do that. <html> <head> <?php $db = mysql_connect("host","name","pass") or die("Can't connect to host"); mysql_select_db("dbname",$db) or die("Can't connect to DB"); $sql_result = mysql_query("SELECT MAX(Thread) FROM test_posts", $db); $rs = mysql_fetch_row($sql_result); $max_threads = $rs[0]; $board = $_GET['board']; ?> </head> <body> <?php While($max_threads >= 0) { $sql_result = mysql_query("SELECT MIN(ID) FROM test_posts WHERE Thread=".$max_threads."", $db); $rs = mysql_fetch_row($sql_result); $sql_result = mysql_query("SELECT post FROM test_posts WHERE ID=".$rs[0]."", $db); $post = mysql_fetch_row($sql_result); $sql_result = mysql_query("SELECT name FROM test_posts WHERE ID=".$rs[0]."", $db); $name = mysql_fetch_row($sql_result); $sql_result = mysql_query("SELECT trip FROM test_posts WHERE ID=".$rs[0]."", $db); $trip = mysql_fetch_row($sql_result); if(!empty($post)) echo'<div class="postbox"><h4>'.$name[0].'['.$trip[0].']</h4><hr />' . $post[0] . '<br /><hr />[<a href="http://prime.programming-designs.com/test_forum/viewthread.php?thread='.$max_threads.'">Reply</a>]</div>'; $max_threads--; } ?> </body> </html>

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  • Strange type-related error

    - by vsb
    I wrote following program: isPrime x = and [x `mod` i /= 0 | i <- [2 .. truncate (sqrt x)]] primes = filter isPrime [1 .. ] it should construct list of prime numbers. But I got this error: [1 of 1] Compiling Main ( 7/main.hs, interpreted ) 7/main.hs:3:16: Ambiguous type variable `a' in the constraints: `Floating a' arising from a use of `isPrime' at 7/main.hs:3:16-22 `RealFrac a' arising from a use of `isPrime' at 7/main.hs:3:16-22 `Integral a' arising from a use of `isPrime' at 7/main.hs:3:16-22 Possible cause: the monomorphism restriction applied to the following: primes :: [a] (bound at 7/main.hs:3:0) Probable fix: give these definition(s) an explicit type signature or use -XNoMonomorphismRestriction Failed, modules loaded: none. If I specify signature for isPrime function explicitly: isPrime :: Integer -> Bool isPrime x = and [x `mod` i /= 0 | i <- [2 .. truncate (sqrt x)]] I can't even compile isPrime function: [1 of 1] Compiling Main ( 7/main.hs, interpreted ) 7/main.hs:2:45: No instance for (RealFrac Integer) arising from a use of `truncate' at 7/main.hs:2:45-61 Possible fix: add an instance declaration for (RealFrac Integer) In the expression: truncate (sqrt x) In the expression: [2 .. truncate (sqrt x)] In a stmt of a list comprehension: i <- [2 .. truncate (sqrt x)] 7/main.hs:2:55: No instance for (Floating Integer) arising from a use of `sqrt' at 7/main.hs:2:55-60 Possible fix: add an instance declaration for (Floating Integer) In the first argument of `truncate', namely `(sqrt x)' In the expression: truncate (sqrt x) In the expression: [2 .. truncate (sqrt x)] Failed, modules loaded: none. Can you help me understand, why am I getting these errors?

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  • Interpretation of range(n) and boolean list, one-to-one map, simpler?

    - by HH
    #!/usr/bin/python # # Description: bitwise factorization and then trying to find # an elegant way to print numbers # Source: http://forums.xkcd.com/viewtopic.php?f=11&t=61300#p2195422 # bug with large numbers such as 99, but main point in simplifying it # def primes(n): # all even numbers greater than 2 are not prime. s = [False]*2 + [True]*2 + [False,True]*((n-4)//2) + [False]*(n%2) i = 3; while i*i < n: # get rid of ** and skip even numbers. s[i*i : n : i*2] = [False]*(1+(n-i*i)//(i*2)) i += 2 # skip non-primes while not s[i]: i += 2 return s # TRIAL: can you find a simpler way to print them? # feeling the overuse of assignments but cannot see a way to get it simpler # p = 49 boolPrimes = primes(p) numbs = range(len(boolPrimes)) mydict = dict(zip(numbs, boolPrimes)) print([numb for numb in numbs if mydict[numb]]) Something I am looking for, can you get TRIAL to be of the extreme simplicity below? Any such method? a=[True, False, True] b=[1,2,3] b_a # any such simple way to get it evaluated to [1,3] # above a crude way to do it in TRIAL

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  • Which Android hardware devices should I test on? [closed]

    - by Tchami
    Possible Duplicate: What hardware devices do you test your Android apps on? I'm trying to compile a list of Android hardware devices that it would make sense to buy and test against if you want to target an as broad audience as possible, while still not buying every single Android device out there. I know there's a lot of information regarding screen sizes and Android versions available elsewhere, but: when developing for Android it's not terribly useful to know if the screen size of a device is 480x800 or 320x240, unless you feel like doing the math to convert that into Android "units" (i.e. small, normal, large or xlarge screens, and ldpi, mdpi, hdpi or xhdpi densities). Even knowing the dimensions of a device, you cannot be sure of the actual Android units as there's some overlap, see Range of screens supported in the Android documentation Taking into account the distribution of Platform versions and Screen Sizes and Densities, below is my current list based on information from the Wikipedia article on Comparison of Android devices. I'm fairly sure the information in this list is correct, but I'd welcome any suggestions/changes. Phones | Model | Android Version | Screen Size | Density | | HTC Wildfire | 2.1/2.2 | Normal | mdpi | | HTC Tattoo | 1.6 | Normal | mdpi | | HTC Hero | 2.1 | Normal | mdpi | | HTC Legend | 2.1 | Normal | mdpi | | Sony Ericsson Xperia X8 | 1.6/2.1 | Normal | mdpi | | Motorola Droid | 2.0-2.2 | Normal | hdpi | | Samsung Galaxy S II | 2.3 | Normal | hdpi | | Samsung Galaxy Nexus | 4.0 | Normal | xhdpi | | Samsung Galaxy S III | 4.0 | Normal | xhdpi | **Tablets** | Model | Android Version | Screen Size | Density | | Samsung Galaxy Tab 7" | 2.2 | Large | hdpi | | Samsung Galaxy Tab 10" | 3.0 | X-Large | mdpi | | Asus Transformer Prime | 4.0 | X-Large | mdpi | | Motorola Xoom | 3.1/4.0 | X-Large | mdpi | N.B.: I have seen (and read) other posts on SO on this subject, e.g. Which Android devices should I test against? and What hardware devices do you test your Android apps on? but they don't seem very canonical. Maybe this should be marked community wiki?

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  • The Importance of a Security Assessment - by Michael Terra, Oracle

    - by Darin Pendergraft
    Today's Blog was written by Michael Terra, who was the Subject Matter Expert for the recently announced Oracle Online Security Assessment. You can take the Online Assessment here: Take the Online Assessment Over the past decade, IT Security has become a recognized and respected Business discipline.  Several factors have contributed to IT Security becoming a core business and organizational enabler including, but not limited to, increased external threats and increased regulatory pressure. Security is also viewed as a key enabler for strategic corporate activities such as mergers and acquisitions.Now, the challenge for senior security professionals is to develop an ongoing dialogue within their organizations about the importance of information security and how it can impact their organization's strategic objectives/mission. The importance of conducting regular “Security Assessments” across the IT and physical infrastructure has become increasingly important. Security standards and frameworks, such as the international standard ISO 27001, are increasingly being adopted by organizations and their business partners as proof of their security posture and “Security Assessments” are a great way to ensure a continued alignment to these frameworks.Oracle offers a number of different security assessment covering a broad range of technologies. Some of these are short engagements conducted for free with our strategic customers and partners. Others are longer term paid engagements delivered by Oracle Consulting Services or one of our partners. The goal of a security assessment, (also known as a security audit or security review), is to ensure that necessary security controls are integrated into the design and implementation of a project, application or technology.  A properly completed security assessment should provide documentation outlining any security gaps that exist in an infrastructure and the associated risks for those gaps. With that knowledge, an organization can choose to either mitigate, transfer, avoid or accept the risk. One example of an Oracle offering is a Security Readiness Assessment:The Oracle Security Readiness Assessment is a practical security architecture review focused on aligning an organization’s enterprise security architecture to their business principals and strategic objectives. The service will establish a multi-phase security architecture roadmap focused on supporting new and existing business initiatives.Offering OverviewThe Security Readiness Assessment will: Define an organization’s current security posture and provide a roadmap to a desired future state architecture by mapping  security solutions to business goals Incorporate commonly accepted security architecture concepts to streamline an organization’s security vision from strategy to implementation Define the people, process and technology implications of the desired future state architecture The objective is to deliver cohesive, best practice security architectures spanning multiple domains that are unique and specific to the context of your organization. Offering DetailsThe Oracle Security Readiness Assessment is a multi-stage process with a dedicated Oracle Security team supporting your organization.  During the course of this free engagement, the team will focus on the following: Review your current business operating model and supporting IT security structures and processes Partner with your organization to establish a future state security architecture leveraging Oracle’s reference architectures, capability maps, and best practices Provide guidance and recommendations on governance practices for the rollout and adoption of your future state security architecture Create an initial business case for the adoption of the future state security architecture If you are interested in finding out more, ask your Sales Consultant or Account Manager for details.

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  • HPC Server Dynamic Job Scheduling: when jobs spawn jobs

    - by JoshReuben
    HPC Job Types HPC has 3 types of jobs http://technet.microsoft.com/en-us/library/cc972750(v=ws.10).aspx · Task Flow – vanilla sequence · Parametric Sweep – concurrently run multiple instances of the same program, each with a different work unit input · MPI – message passing between master & slave tasks But when you try go outside the box – job tasks that spawn jobs, blocking the parent task – you run the risk of resource starvation, deadlocks, and recursive, non-converging or exponential blow-up. The solution to this is to write some performance monitoring and job scheduling code. You can do this in 2 ways: manually control scheduling - allocate/ de-allocate resources, change job priorities, pause & resume tasks , restrict long running tasks to specific compute clusters Semi-automatically - set threshold params for scheduling. How – Control Job Scheduling In order to manage the tasks and resources that are associated with a job, you will need to access the ISchedulerJob interface - http://msdn.microsoft.com/en-us/library/microsoft.hpc.scheduler.ischedulerjob_members(v=vs.85).aspx This really allows you to control how a job is run – you can access & tweak the following features: max / min resource values whether job resources can grow / shrink, and whether jobs can be pre-empted, whether the job is exclusive per node the creator process id & the job pool timestamp of job creation & completion job priority, hold time & run time limit Re-queue count Job progress Max/ min Number of cores, nodes, sockets, RAM Dynamic task list – can add / cancel jobs on the fly Job counters When – poll perf counters Tweaking the job scheduler should be done on the basis of resource utilization according to PerfMon counters – HPC exposes 2 Perf objects: Compute Clusters, Compute Nodes http://technet.microsoft.com/en-us/library/cc720058(v=ws.10).aspx You can monitor running jobs according to dynamic thresholds – use your own discretion: Percentage processor time Number of running jobs Number of running tasks Total number of processors Number of processors in use Number of processors idle Number of serial tasks Number of parallel tasks Design Your algorithms correctly Finally , don’t assume you have unlimited compute resources in your cluster – design your algorithms with the following factors in mind: · Branching factor - http://en.wikipedia.org/wiki/Branching_factor - dynamically optimize the number of children per node · cutoffs to prevent explosions - http://en.wikipedia.org/wiki/Limit_of_a_sequence - not all functions converge after n attempts. You also need a threshold of good enough, diminishing returns · heuristic shortcuts - http://en.wikipedia.org/wiki/Heuristic - sometimes an exhaustive search is impractical and short cuts are suitable · Pruning http://en.wikipedia.org/wiki/Pruning_(algorithm) – remove / de-prioritize unnecessary tree branches · avoid local minima / maxima - http://en.wikipedia.org/wiki/Local_minima - sometimes an algorithm cant converge because it gets stuck in a local saddle – try simulated annealing, hill climbing or genetic algorithms to get out of these ruts   watch out for rounding errors – http://en.wikipedia.org/wiki/Round-off_error - multiple iterations can in parallel can quickly amplify & blow up your algo ! Use an epsilon, avoid floating point errors,  truncations, approximations Happy Coding !

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  • Week 21: FY10 in the Rear View Mirror

    - by sandra.haan
    FY10 is coming to a close and before we dive into FY11 we thought we would take a walk down memory lane and reminisce on some of our favorite Oracle PartnerNetwork activities. June 2009 brought One Red Network to partners offering access to the same virtual kickoff environment used by Oracle employees. It was a new way to deliver valuable content to key stakeholders (and without the 100+ degree temperatures). Speaking of hot, Oracle also announced in June new licensing options for our ISV partners. This model enables an even broader community of ISVs to build, deploy and manage SaaS applications on the same platform. While some people took the summer off, the OPN Program team was working away to deliver a brand new partner program - Oracle PartnerNetwork Specialized - at Oracle OpenWorld in October. Specialized. Recognized. Preferred. If you haven't gotten the message yet, we may need an emergency crew to pull you out from that rock you've been hiding under. But seriously, the announcement at the OPN Forum drew a big crowd and our FY11 event is shaping up to be just as exciting. OPN Specialized was announced in October and opened our doors for enrollment in December 2009. To mark our grand opening we held our first ever social webcast allowing partners from around the world to interact with us live throughout the day. We had a lot of great conversations and really enjoyed the chance to speak with so many of you. After a short holiday break we were back at it - just a small announcement - Oracle's acquisition of Sun. In case you missed it, here is a short field report from Ted Bereswill, SVP North America Alliances & Channels on the partner events to support the announcement: And while we're announcing things - did we mention that both Ted Bereswill and Judson Althoff were named Channel Chiefs by CRN? Not only do we have a couple of Channel Chiefs, but Oracle also won the Partner Program 5 Star Programs Award and took top honors at the CRN Channel Champion Awards for Financial Factors/Financial Performance in the category of Data and Information Management and the and Xchange Solution Provider event in March 2010. We actually caught up with Judson at this event for a quick recap of our participation: But awards aside, let's not forget our main focus in FY10 and that is Specialization. In April we announced that we had over 35 Specializations available for partners and a plan to deliver even more in FY11. We are just days away from the end of FY10 but hope you enjoyed our walk down memory lane. We are already planning lots of activity for our partners in FY11 starting with our Partner Kickoff event on June 29th. Join us to hear the vision and strategy for FY11 and interact with regional A&C leaders. We look forward to talking with you then. The OPN Communications Team

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  • Oracle VM Deep Dives

    - by rickramsey
    "With IT staff now tasked to deliver on-demand services, datacenter virtualization requirements have gone beyond simple consolidation and cost reduction. Simply provisioning and delivering an operating environment falls short. IT organizations must rapidly deliver services, such as infrastructure-as-a-service (IaaS), platform-as-a-service (PaaS), and software-as-a-service (SaaS). Virtualization solutions need to be application-driven and enable:" "Easier deployment and management of business critical applications" "Rapid and automated provisioning of the entire application stack inside the virtual machine" "Integrated management of the complete stack including the VM and the applications running inside the VM." Application Driven Virtualization, an Oracle white paper That was published in August of 2011. The new release of Oracle VM Server delivers significant virtual networking performance improvements, among other things. If you're not sure how virtual networks work or how to use them, these two articles by Greg King and friends might help. Looking Under the Hood at Virtual Networking by Greg King Oracle VM Server for x86 lets you create logical networks out of physical Ethernet ports, bonded ports, VLAN segments, virtual MAC addresses (VNICs), and network channels. You can then assign channels (or "roles") to each logical network so that it handles the type of traffic you want it to. Greg King explains how you go about doing this, and how Oracle VM Server for x86 implements the network infrastructure you configured. He also describes how the VM interacts with paravirtualized guest operating systems, hardware virtualized operating systems, and VLANs. Finally, he provides an example that shows you how it all looks from the VM Manager view, the logical view, and the command line view of Oracle VM Server for x86. Fundamental Concepts of VLAN Networks by Greg King and Don Smerker Oracle VM Server for x86 supports a wide range of options in network design, varying in complexity from a single network to configurations that include network bonds, VLANS, bridges, and multiple networks connecting the Oracle VM servers and guests. You can create separate networks to isolate traffic, or you can configure a single network for multiple roles. Network design depends on many factors, including the number and type of network interfaces, reliability and performance goals, the number of Oracle VM servers and guests, and the anticipated workload. The Oracle VM Manager GUI presents four different ways to create an Oracle VM network: Bonds and ports VLANs Both bond/ports and VLANS A local network This article focuses the second option, designing a complex Oracle VM network infrastructure using only VLANs, and it steps through the concepts needed to create a robust network infrastructure for your Oracle VM servers and guests. More Resources Virtual Networking for Dummies Download Oracle VM Server for x86 Find technical resources for Oracle VM Server for x86 -Rick Follow me on: Blog | Facebook | Twitter | Personal Twitter | YouTube | The Great Peruvian Novel

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  • Recruitment Drive - Things Don't Always Go As Planned - Stay Flexible by Kalyan Neelagiri

    - by david.talamelli
    I am one of the Recruiters for Oracle and work in our India Recruitment Team. When we are hiring for multiple positions we often hold Recruitment Events to interview a large number of people as effectively as possible. These Events are often held on the weekend as many people are not free to attend an all day event during the working week. Just recently during a recruitment campaign we were running I was tasked to set up a Recruitment Event for some roles we were hiring for. I have set up and run weekend recruitment events in the past which have all run smoothly. However, this time arranging this recruitment event was quite a challenge for me. The planned event was taking place on a Saturday. I had almost sent out the confirmed scheduled list of candidates to the respective hiring team on Friday and was on track for the event to take place, but unfortunately there was breaking news in the media that there was a strike called in the city because of some political agitations and protests taking place on the event day. The hiring manager had rushed to me asking for my thoughts and ideas. I was in two minds on what to do. One on hand I was not ready to cancel the event because of all the work that so many people had put into getting this prepared and also I did not want to reschedule the event at the last minute if I did not need to. On the other hand I understood it may be best to reschedule the event as people may not be able to attend based on the political protests taking place on the day. In the end I decided to gather and check for other options because this might cause confusion and a problem for the scheduled candidates to drive in to the venue. So we had concluded to reschedule our event plans and moved the event to the next week. The good news is that we successfully executed this recruitment drive the following Saturday. We were glad that 100% of the candidates we able to make it to the new interview date and despite all the agitations in the city we were successful in hiring people for all the roles we had open. Things do not always go as planned. The best laid plans can sometimes be for nought based on external factors outside of our control. What this experience has taught me is that rather than focus on the negatives when you are thrown a curveball the best approach is to stay flexible and focus on finding ways to reach your outcome. Your plans may need to change but you can still achieve the results you are after if you have the right mind set.

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  • Iterative and Incremental Principle Series 3: The Implementation Plan (a.k.a The Fitness Plan)

    - by llowitz
    Welcome back to the Iterative and Incremental Blog series.  Yesterday, I demonstrated how shorter interval sets allowed me to focus on my fitness goals and achieve success.  Likewise, in a project setting, shorter milestones allow the project team to maintain focus and experience a sense of accomplishment throughout the project lifecycle.  Today, I will discuss project planning and how to effectively plan your iterations. Admittedly, there is more to applying the iterative and incremental principle than breaking long durations into multiple, shorter ones.  In order to effectively apply the iterative and incremental approach, one should start by creating an implementation plan.   In a project setting, the Implementation Plan is a high level plan that focuses on milestones, objectives, and the number of iterations.  It is the plan that is typically developed at the start of an engagement identifying the project phases and milestones.  When the iterative and incremental principle is applied, the Implementation Plan also identified the number of iterations planned for each phase.  The implementation plan does not include the detailed plan for the iterations, as this detail is determined prior to each iteration start during Iteration Planning.  An individual iteration plan is created for each project iteration. For my fitness regime, I also created an “Implementation Plan” for my weekly exercise.   My high level plan included exercising 6 days a week, and since I cross train, trying not to repeat the same exercise two days in a row.  Because running on the hills outside is the most difficult and consequently, the most effective exercise, my implementation plan includes running outside at least 2 times a week.   Regardless of the exercise selected, I always apply a series of 6-minute interval sets.  I never plan what I will do each day in advance because there are too many changing factors that need to be considered before that level of detail is determined.  If my Implementation Plan included details on the exercise I was to perform each day of the week, it is quite certain that I would be unable to follow my plan to that level.  It is unrealistic to plan each day of the week without considering the unique circumstances at that time.  For example, what is the weather?  Are there are conflicting schedule commitments?  Are there injuries that need to be considered?  Likewise, in a project setting, it is best to plan for the iteration details prior to its start. Join me for tomorrow’s blog where I will discuss when and how to plan the details of your iterations.

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  • What are the options for hosting a small Plone site? [closed]

    - by Tina Russell
    Possible Duplicate: How to find web hosting that meets my requirements? I’ve developed a portfolio website for myself using Plone 4, and I’m looking for someplace to host it. Most Plone hosting services seem to focus on large, corporate deployments, but I need something that I can afford on a very limited budget and fits a small, single-admin website. My understanding is that my basic options are thus: I can go with a hosting service that specifically provides Plone. I know of WebFaction, but what others exist? Also, I’d have two stipulations for a Plone hosting service: (a) It needs to use Plone 4, for which I’ve developed my site, and (b) it needs to allow me SSH access to a home directory (including the Plone configuration), so that I may use my custom development eggs and such. I could use a VPS hosting service. What are my options here? Again, I need something cheap and scaled to my level. I could use Amazon EC2 or a similar service (please tell me of any) and pay by the tiniest unit of data. I’m a little scared of this because I have no idea how to do a cost-benefit analysis between this and a regular VPS host. The advantage of this approach would be that I only pay for what I use, making it very scalable, but I don’t know how the overall cost would compare to any VPS host under similar circumstances. What factors enter into the cost of Amazon EC2? What can I expect to pay under either option for regular traffic for a new website? Which one is more desirable for when a rush of visitors drive up my bandwidth bill? One last note: I know Plone isn’t common for websites for individuals, but please don’t try to talk me out of it here; that’s a completely different subject. For now, assume I’m sticking with Plone for good. Also, I have seen the Plone hosting services list on Plone.org—it’s twenty pages long, and the first page was nothing but professional Plone consulting services that sometimes offer hosting for business clients. So, that wasn’t much help. Thank you!

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  • What Is Nuclear Meltdown?

    - by Gopinath
    Japan was first hit by a massive earth quake, then a ruthless tsunami washed away thousands of homes and now they fear the worst – meltdown of nuclear power stations in the quake hit year. Nuclear meltdowns are horrifying – remember the Chernobyl incident in Russia? The Chernobyl reactor meltdown released 400 times more radio active material than the atomic bombing of Hiroshima. The effects of nuclear meltdowns are beyond imagination of a common man, thousands of people loose their lives and many more lakhs of people suffer with radiation related diseases for many years. Nuclear Meltdowns are dangerous, but how do they happen? What causes a nuclear meltdown? In simple terms – Nuclear meltdown is an accident that happens due to severe overheating of a nuclear reactor and results in release of nuclear radiation into the environment.  How A Nuclear Meltdown Happens? According to Wikipedia A meltdown occurs when a severe failure of a nuclear power plant system prevents proper cooling of the reactor core, to the extent that the nuclear fuel assemblies overheat and melt. A meltdown is considered very serious because of the potential that radioactive materials could be released into the environment. The fuel assemblies in a reactor core can melt if heat is not removed. A nuclear reactor does not have to remain critical for a core damage incident to occur, because decay heat continues to heat the reactor fuel assemblies after the reactor has shut down, though this heat decreases with time. A core damage accident is caused by the loss of sufficient cooling for the nuclear fuel within the reactor core. The reason may be one of several factors, including a loss of pressure control accident, a loss of coolant accident (LOCA), an uncontrolled power excursion or, in some types, a fire within the reactor core. Failures in control systems may cause a series of events resulting in loss of cooling. Contemporary safety principles of defense in depth, ensure that multiple layers of safety systems are always present to make such accidents unlikely. Video – What Causes Nuclear Meltdown AlJazeera news has a good analysis on feared nuclear meltdown of Japan’s nuclear plants and also an animation on what causes Nuclear Meltdown. cc image credit: flickr/jtjdt This article titled,What Is Nuclear Meltdown?, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • How To Build An Enterprise Application - Introduction

    - by Tuan Nguyen
    An enterprise application is a software which fulfills 4 core quality attributes: Reliability Flexibility Reusability Maintainability Reliability is the ability of a system or component to perform its required functions under stated conditions for a specific period of time. Because there are no ways more than testing to make sure a system is reliability, we can exchange the term reliability with the term testability. Flexibility is the ability of changing a system's core features without violating unrelated features or components. Although flexibility can helps us to achieve interoperability easily but the opposite is not true. For example, a program might run on multiple platforms, contains logic for many scenarios but that wouldn't mean it was flexibility if it forces us rewrite code in all components when we just want to change some aspects of a feature it had. Reusability is the ability of sharing one or more system's components for another system. We should just open a component's reusability in the context in which it is used. For example, we write classes that implement UI logic and deliver them to only classes which implementing UI. Maintainability is the ability of adding or removing features to a system after it was released. Maintainability consists of many factors such as readability, analyzability, extensibility therein extensibility is critical. Maintainability requires us to write code that is longer and complexer than normal but it doesn't mean we introduce unneccessarily complex code. We always try to make our code clear and transparent to everyone. An application enterprise is built on an enterprise design which consists of two parts: low-level design and high-level design. At low-level design, it focuses on building loose-coupled classes or components. Particularly, it recommends: Each class or component undertakes only single responsibility (design based on unit test) Classes or components implement and work through interfaces (design based on contract) Dependency relationship between classes and components could be injected at run-time (design based on dependency) At high-level design, it focuses on architecting system into tiers and layers. Particularly, it recommends: Divide system into subsystems for deployment. Each subsytem is called a tier. Typical, an enterprise application would have 3 tiers as illustrated in the following figure: Arrange classes and components to logical containers called layers. Typical, an enterprise application would have 5 layers as illustrated in the following figure

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