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  • Effect.toggle and AJAX Calls

    - by kunalsawlani
    Hi, I am using the following code to capture all the AJAX calls being made from my app, in order to show a busy spinner till the call is completed. It works well when the requests are well spaced out. However, when the request are made in quick successions, some of the AJAX calls do not get registered, or the onCreate and onComplete actions get kicked off at the same time, and more often than not, the busy spinner continues to appear on the screen, after all the calls have successfully completed. Is there any check I can perform at the end of the call, to check if the element is visible, I can hide it. document.observe("dom:loaded", function() { $('loading').hide(); Ajax.Responders.register({ //When an Ajax call is made. onCreate: function() { new Effect.toggle('loading', 'appear'); new Effect.Opacity('display-area', { from: 1.0, to: 0.3, duration: 0.7 }); }, onComplete: function() { new Effect.toggle('loading', 'appear'); new Effect.Opacity('display-area', { from: 0.3, to: 1, duration: 0.7 }); } }); }); Thanks!

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  • Rails 2.3.4 and jquery form plugin works on development, not in production?

    - by hemajang
    Hello, i'm trying to build a contact form in Rails 2.3.4. I'm using the jQuery Form plugin along with this (http://bassistance.de/jquery-plugins/jquery-plugin-validation/) for validations. Everything works in my development environment (mac os x snow leopard), the loading gif appears and on my log the email gets sent and the "request completed" notice shows. But on my production machine the loading gif just keeps going and the form doesn't get sent. I've waited as long as I could, nothing. Here is my code: /public/javascripts/application.js // client-side validation and ajax submit contact form $('#contactForm').validate( { rules: { 'email[name]': { required: true }, 'email[address]': { required: true, email: true }, 'email[subject]': { required: true }, 'email[body]': { required: true } }, messages: { 'email[name]': "Please enter your name.", 'email[address]': "Please enter a valid email address.", 'email[subject]': "Please enter a subject.", 'email[body]': "Please enter a message." }, submitHandler: function(form) { $(form).ajaxSubmit({ dataType: 'script', beforeSend: function() { $(".loadMsg").show(); } }); return false; } }); I'm using the submitHandler to send the actual ajaxSubmit. I added the "dataType: "script" and the "beforeSubmit" for the loading graphic. def send_mail if request.post? respond_to do |wants| ContactMailer.deliver_contact_request(params[:email]) flash[:notice] = "Email was successfully sent." wants.js end end end Everything works fine on development, but not in production. What am I missing or did wrong?

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  • click event working in Chrome but error in Firefox and IE

    - by Hunter Stanchak
    I am writing a messaging system with jquery. When you click on a thread title with the class '.open_message', It opens a thread with all the messages for that thread via Ajax. My issue is that when the thread title is clicked it is not recognizing the id attribute for that specific thread title in firefox and IE. It works fine in chrome, though. Here is the code: $('.open_message').on('click', function(e) { $(this).parent().removeClass('unread'); $(this).parent().addClass('read'); $('.message_container').html(''); var theID = e.currentTarget.attributes[0].value; theID = theID.replace('#', ''); var url = '".$url."'; var dataString = 'thread_id=' + theID; $('.message_container').append('<img id=\"loading\" src=\"' + url + '/images/loading.gif\" width=\"30px\" />'); $.ajax({ type: 'POST', url: 'get_thread.php', data: dataString, success: function(result) { $('#loading').hide(); $('.message_container').append(result); } }); return false; }); Thanks for the help!

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  • Hibernate Performance Best Practice?

    - by user829237
    Im writing a Web application using Hibernate 3. So, after a while i noticed that something was slow. So i tested hibernate profiler and found that hibernate will make unreasonably many db-calls for simple operation. The reason is ofcourse that i load an Object (this object has several "parents") and these "parents" have other "parents". So basicly hibernate loads them all, even though i just need the basic object. Ok, so i looked into lazy-loading. Which lead me into the Lazyloading-exception, because i have a MVC webapp. So now i'm a bit confused as to what is my best approach to this. Basicly all I need is to update a single field on an object. I already have the object-key. Should I: 1. Dig into Lazy-loading. And then rewrite my app for a open-session-view? 2. Dig into lazy-loading. And then rewrite my dao's to be more specific. E.g. writing DAO-methods that will return objects instanciated with only whats necessary for each use-case? Could be a lot of extra methods... 3. Scratch hibernate and do it myself? 4. Cant really think of other solutions right now. Any suggestions? What is the best practice?

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  • setContentView taking long time (10-15 seconds) to execute

    - by Paul
    I have a large activity that contains 100 or more buttons. But it's working fine once loaded. Problem however is loading. From clicking its launch icon to getting the first view it takes 10-12 seconds. Until the first view, it shows gray title bar in black background. At least, I want to show a simple progress bar or dialog while its loading. But it seems like you cannot show anything before setContentView executed. I think I have tried everything I could without any success. If you can give me any hint or idea, I would be thankful. UPDATE: I found a dramatic resolution. It takes now a second to load the view. I didn't use splash, thread or async task at all - BTW, don't try to use thread or async on UI because Android UI is not thread-safe. Problem was that those buttons were based on a custom class that requires initialization to load same resource. - so 100 or more file operations were happening on setContentView. Making them a just single loading solved my problem.

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  • A Taxonomy of Numerical Methods v1

    - by JoshReuben
    Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

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  • Automatic Standby Recreation for Data Guard

    - by pablo.boixeda(at)oracle.com
    Hi,Unfortunately sometimes a Standby Instance needs to be recreated. This can happen for many reasons such as lost archive logs, standby data files, failover, among others.This is why we wanted to have one script to recreate standby instances in an easy way.This script recreates the standby considering some prereqs:-Database Version should be at least 11gR1-Dummy instance started on the standby node (Seeking to improve this so it won't be needed)-Broker configuration hasn't been removed-In our case we have two TNSNAMES files, one for the Standby creation (using SID) and the other one for production using service names (including broker service name)-Some environment variables set up by the environment db script (like ORACLE_HOME, PATH...)-The directory tree should not have been modified in the stanby hostWe are currently using it on our 11gR2 Data Guard tests.Any improvements will be welcome! Normal 0 21 false false false ES X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} #!/bin/ksh ###    NOMBRE / VERSION ###       recrea_dg.sh   v.1.00 ### ###    DESCRIPCION ###       reacreacion de la Standby ### ###    DEVUELVE ###       0 Creacion de STANDBY correcta ###       1 Fallo ### ###    NOTAS ###       Este shell script NO DEBE MODIFICARSE. ###       Todas las variables y constantes necesarias se toman del entorno. ### ###    MODIFICADO POR:    FECHA:        COMENTARIOS: ###    ---------------    ----------    ------------------------------------- ###      Oracle           15/02/2011    Creacion. ### ### ### Cargar entorno ### V_ADMIN_DIR=`dirname $0` . ${V_ADMIN_DIR}/entorno_bd.sh 1>>/dev/null if [ $? -ne 0 ] then   echo "Error Loading the environment."   exit 1 fi V_RET=0 V_DATE=`/bin/date` V_DATE_F=`/bin/date +%Y%m%d_%H%M%S` V_LOGFILE=${V_TRAZAS}/recrea_dg_${V_DATE_F}.log exec 4>&1 tee ${V_FICH_LOG} >&4 |& exec 1>&p 2>&1 ### ### Variables para Recrear el Data Guard ### V_DB_BR=`echo ${V_DB_NAME}|tr '[:lower:]' '[:upper:]'` if [ "${ORACLE_SID}" = "${V_DB_NAME}01" ] then         V_LOCAL_BR=${V_DB_BR}'01'         V_REMOTE_BR=${V_DB_BR}'02' else         V_LOCAL_BR=${V_DB_BR}'02'         V_REMOTE_BR=${V_DB_BR}'01' fi echo " Getting local instance ROLE ${ORACLE_SID} ..." sqlplus -s /nolog 1>>/dev/null 2>&1 <<-! whenever sqlerror exit 1 connect / as sysdba variable salida number declare   v_database_role v\$database.database_role%type; begin   select database_role into v_database_role from v\$database;   :salida := case v_database_role        when 'PRIMARY' then 2        when 'PHYSICAL STANDBY' then 3        else 4      end; end; / exit :salida ! case $? in 1) echo " ERROR: Cannot get instance ROLE ." | tee -a ${V_LOGFILE}   2>&1    V_RET=1 ;; 2) echo " Local Instance with PRIMARY role." | tee -a ${V_LOGFILE}   2>&1    V_DB_ROLE_LCL=PRIMARY ;; 3) echo " Local Instance with PHYSICAL STANDBY role." | tee -a ${V_LOGFILE}   2>&1    V_DB_ROLE_LCL=STANDBY ;; *) echo " ERROR: UNKNOWN ROLE." | tee -a ${V_LOGFILE}   2>&1    V_RET=1 ;; esac if [ "${V_DB_ROLE_LCL}" = "PRIMARY" ] then         echo "####################################################################" | tee -a ${V_LOGFILE}   2>&1         echo "${V_DATE} - Reacreating  STANDBY Instance." | tee -a ${V_LOGFILE}   2>&1         echo "" | tee -a ${V_LOGFILE}   2>&1         echo "DATAFILES, CONTROL FILES, REDO LOGS and ARCHIVE LOGS in standby instance ${V_REMOTE_BR} will be removed" | tee -a ${V_LOGFILE}   2>&1         echo "" | tee -a ${V_LOGFILE}   2>&1         V_PRIMARY=${V_LOCAL_BR}         V_STANDBY=${V_REMOTE_BR} fi if [ "${V_DB_ROLE_LCL}" = "STANDBY" ] then         echo "####################################################################" | tee -a ${V_LOGFILE}   2>&1         echo "${V_DATE} - Reacreating  STANDBY Instance." | tee -a ${V_LOGFILE}   2>&1         echo "" | tee -a ${V_LOGFILE}   2>&1         echo "DATAFILES, CONTROL FILES, REDO LOGS and ARCHIVE LOGS in standby instance ${V_LOCAL_BR} will be removed" | tee -a ${V_LOGFILE}   2>&1         echo "" | tee -a ${V_LOGFILE}   2>&1         V_PRIMARY=${V_REMOTE_BR}         V_STANDBY=${V_LOCAL_BR} fi # Cargamos las variables de los hosts # Cargamos las variables de los hosts PRY_HOST=`sqlplus  /nolog << EOF | grep KEEP | sed 's/KEEP//;s/[   ]//g' connect sys/${V_DB_PWD}@${V_PRIMARY} as sysdba select 'KEEP',host_name from v\\$instance; EOF` SBY_HOST=`sqlplus  /nolog << EOF | grep KEEP | sed 's/KEEP//;s/[   ]//g' connect sys/${V_DB_PWD}@${V_STANDBY} as sysdba select 'KEEP',host_name from v\\$instance; EOF` echo "el HOST primary es: ${PRY_HOST}" | tee -a ${V_LOGFILE}   2>&1 echo "el HOST standby es: ${SBY_HOST}" | tee -a ${V_LOGFILE}   2>&1 echo "" | tee -a ${V_LOGFILE}   2>&1 ## ## Paramos la instancia STANDBY ## V_DATE=`/bin/date` echo "${V_DATE} - Shutting down Standby instance" | tee -a ${V_LOGFILE}   2>&1 echo "" | tee -a ${V_LOGFILE}   2>&1 echo "********************************************************************************" | tee -a ${V_LOGFILE}   2>&1 ## ## Paramos la instancia STANDBY ## SBY_STATUS=`sqlplus  /nolog << EOF | grep KEEP | sed 's/KEEP//;s/[   ]//g' connect sys/${V_DB_PWD}@${V_STANDBY} as sysdba select 'KEEP',status from v\\$instance; EOF` if [ ${SBY_STATUS} = 'STARTED' ] || [ ${SBY_STATUS} = 'MOUNTED' ] || [ ${SBY_STATUS} = 'OPEN' ] then         echo "${V_DATE} - Standby instance shutdown in progress..." | tee -a ${V_LOGFILE}   2>&1         echo "" | tee -a ${V_LOGFILE}   2>&1         echo "********************************************************************************" | tee -a ${V_LOGFILE}   2>&1         sqlplus -s /nolog 1>>/dev/null 2>&1 <<-!         whenever sqlerror exit 1         connect sys/${V_DB_PWD}@${V_STANDBY} as sysdba         shutdown abort         ! fi V_DATE=`/bin/date` echo "" echo "${V_DATE} - Standby instance stopped" | tee -a ${V_LOGFILE}   2>&1 echo "" | tee -a ${V_LOGFILE}   2>&1 echo "********************************************************************************" | tee -a ${V_LOGFILE}   2>&1 ## ## Eliminamos los ficheros de la base de datos ## V_SBY_SID=`echo ${V_STANDBY}|tr '[:upper:]' '[:lower:]'` V_PRY_SID=`echo ${V_PRIMARY}|tr '[:upper:]' '[:lower:]'` ssh ${SBY_HOST} rm /opt/oracle/db/db${V_DB_NAME}/${V_SBY_SID}/data/*.dbf ssh ${SBY_HOST} rm /opt/oracle/db/db${V_DB_NAME}/${V_SBY_SID}/arch/*.arc ssh ${SBY_HOST} rm /opt/oracle/db/db${V_DB_NAME}/${V_SBY_SID}/ctl/*.ctl ssh ${SBY_HOST} rm /opt/oracle/db/db${V_DB_NAME}/${V_SBY_SID}/redo/*.ctl ssh ${SBY_HOST} rm /opt/oracle/db/db${V_DB_NAME}/${V_SBY_SID}/redo/*.rdo ## ## Startup nomount stby instance ## V_DATE=`/bin/date` echo "" | tee -a ${V_LOGFILE}   2>&1 echo "${V_DATE} - Starting  DUMMY Standby Instance " | tee -a ${V_LOGFILE}   2>&1 echo "" | tee -a ${V_LOGFILE}   2>&1 echo "********************************************************************************" | tee -a ${V_LOGFILE}   2>&1 ssh ${SBY_HOST} touch /home/oracle/init_dg.ora ssh ${SBY_HOST} 'echo "DB_NAME='${V_DB_NAME}'">>/home/oracle/init_dg.ora' ssh ${SBY_HOST} touch /home/oracle/start_dummy.sh ssh ${SBY_HOST} 'echo "ORACLE_HOME=/opt/oracle/db/db'${V_DB_NAME}'/soft/db11.2.0.2 ">>/home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'echo "export ORACLE_HOME">>/home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'echo "PATH=\$ORACLE_HOME/bin:\$PATH">>/home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'echo "export PATH">>/home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'echo "ORACLE_SID='${V_SBY_SID}'">>/home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'echo "export ORACLE_SID">>/home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'echo "sqlplus -s /nolog <<-!" >>/home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'echo "      whenever sqlerror exit 1 ">>/home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'echo "      connect / as sysdba ">>/home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'echo "      startup nomount pfile='\''/home/oracle/init_dg.ora'\''">>/home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'echo "! ">>/home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'chmod 744 /home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'sh /home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'rm /home/oracle/start_dummy.sh' ssh ${SBY_HOST} 'rm /home/oracle/init_dg.ora' ## ## TNSNAMES change, specific for RMAN duplicate ## V_DATE=`/bin/date` echo "" | tee -a ${V_LOGFILE}   2>&1 echo "${V_DATE} - Setting up TNSNAMES in PRIMARY host " | tee -a ${V_LOGFILE}   2>&1 echo "" | tee -a ${V_LOGFILE}   2>&1 echo "********************************************************************************" | tee -a ${V_LOGFILE}   2>&1 ssh ${PRY_HOST} 'cp /opt/oracle/db/db'${V_DB_NAME}'/soft/db11.2.0.2/network/admin/tnsnames.ora.inst  /opt/oracle/db/db'${V_DB_NAME}'/soft/db11.2.0.2/network/admin/tnsnames.ora' V_DATE=`/bin/date` echo "" | tee -a ${V_LOGFILE}   2>&1 echo "${V_DATE} - Starting STANDBY creation with RMAN.. " | tee -a ${V_LOGFILE}   2>&1 echo "" | tee -a ${V_LOGFILE}   2>&1 echo "********************************************************************************" | tee -a ${V_LOGFILE}   2>&1 rman<<-! >>${V_LOGFILE} connect target sys/${V_DB_PWD}@${V_PRIMARY} connect auxiliary sys/${V_DB_PWD}@${V_STANDBY} run { allocate channel prmy1 type disk; allocate channel prmy2 type disk; allocate channel prmy3 type disk; allocate channel prmy4 type disk; allocate auxiliary channel stby type disk; duplicate target database for standby from active database dorecover spfile parameter_value_convert '${V_PRY_SID}','${V_SBY_SID}' set control_files='/opt/oracle/db/db${V_DB_NAME}/${V_SBY_SID}/ctl/control01.ctl','/opt/oracle/db/db${V_DB_NAME}/${V_SBY_SID}/redo/control02.ctl' set db_file_name_convert='/opt/oracle/db/db${V_DB_NAME}/${V_PRY_SID}/','/opt/oracle/db/db${V_DB_NAME}/${V_SBY_SID}/' set log_file_name_convert='/opt/oracle/db/db${V_DB_NAME}/${V_PRY_SID}/','/opt/oracle/db/db${V_DB_NAME}/${V_SBY_SID}/' set 'db_unique_name'='${V_SBY_SID}' set log_archive_config='DG_CONFIG=(${V_PRIMARY},${V_STANDBY})' set fal_client='${V_STANDBY}' set fal_server='${V_PRIMARY}' set log_archive_dest_1='LOCATION=/opt/oracle/db/db${V_DB_NAME}/${V_SBY_SID}/arch DB_UNIQUE_NAME=${V_SBY_SID} MANDATORY VALID_FOR=(ALL_LOGFILES,ALL_ROLES)' set log_archive_dest_2='SERVICE="${V_PRIMARY}"','SYNC AFFIRM DB_UNIQUE_NAME=${V_PRY_SID} DELAY=0 MAX_FAILURE=0 REOPEN=300 REGISTER VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)' nofilenamecheck ; } ! V_DATE=`/bin/date` if [ $? -ne 0 ] then         echo ""         echo "${V_DATE} - Error creating STANDBY instance"         echo ""         echo "********************************************************************************" else         echo ""         echo "${V_DATE} - STANDBY instance created SUCCESSFULLY "         echo ""         echo "********************************************************************************" fi sqlplus -s /nolog 1>>/dev/null 2>&1 <<-!         whenever sqlerror exit 1         connect sys/${V_DB_PWD}@${V_STANDBY} as sysdba         alter system set local_listener='(ADDRESS=(PROTOCOL=TCP)(HOST=${SBY_HOST})(PORT=1544))' scope=both;         alter system set service_names='${V_DB_NAME}.eu.roca.net,${V_SBY_SID}.eu.roca.net,${V_SBY_SID}_DGMGRL.eu.roca.net' scope=both;         alter database recover managed standby database using current logfile disconnect from session;         alter system set dg_broker_start=true scope=both; ! ## ## TNSNAMES change, back to Production Mode ## V_DATE=`/bin/date` echo " " | tee -a ${V_LOGFILE}   2>&1 echo "${V_DATE} - Restoring TNSNAMES in PRIMARY "  | tee -a ${V_LOGFILE}   2>&1 echo ""  | tee -a ${V_LOGFILE}   2>&1 echo "********************************************************************************"  | tee -a ${V_LOGFILE}   2>&1 ssh ${PRY_HOST} 'cp /opt/oracle/db/db'${V_DB_NAME}'/soft/db11.2.0.2/network/admin/tnsnames.ora.prod  /opt/oracle/db/db'${V_DB_NAME}'/soft/db11.2.0.2/network/admin/tnsnames.ora' echo ""  | tee -a ${V_LOGFILE}   2>&1 echo "${V_DATE} -  Waiting for media recovery before check the DATA GUARD Broker"  | tee -a ${V_LOGFILE}   2>&1 echo ""  | tee -a ${V_LOGFILE}   2>&1 echo "********************************************************************************"  | tee -a ${V_LOGFILE}   2>&1 sleep 200 dgmgrl <<-! | grep SUCCESS 1>/dev/null 2>&1     connect ${V_DB_USR}/${V_DB_PWD}@${V_STANDBY}     show configuration verbose; ! if [ $? -ne 0 ] ; then         echo "       ERROR: El status del Broker no es SUCCESS" | tee -a ${V_LOGFILE}   2>&1 ;         V_RET=1 else          echo "      DATA GUARD OK " | tee -a ${V_LOGFILE}   2>&1 ; Normal 0 21 false false false ES X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}         V_RET=0 fi Hope it helps.

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  • PTLQueue : a scalable bounded-capacity MPMC queue

    - by Dave
    Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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  • Execute a SQlite command with Entity Framework

    - by Filimindji
    Hi everybody, I use a SQLite database and Entity Framework (with .net framework 3.5). I'm trying to execute a simple SQL non query command to create a new table in this datase. My Entity Framework already contains the object model for this table : I just want to generate the corresponding table using a command. (By the way, there is maybe a better way to do this. Any ideas someone :) My problem is that I'm not able to execute any command, even the simple commands. Here is my code : EntityConnection entityConnection = new EntityConnection(entitiesConnectionString); Entities db = new Entities(entityConnection); DbCommand command = db.Connection.CreateCommand(); command.CommandText ="CREATE TABLE MyTable (Id int NOT NULL, OtherTable_Id nchar(40) REFERENCES OtherTable (Id) On Delete CASCADE On Update NO ACTION, SomeData nvarchar(1024) NOT NULL, Primary Key(Id) );"; command.ExecuteNonQuery(); I got this error : System.Data.EntitySqlException: The query syntax is not valid., near identifier 'TABLE', line 1, column 8. at System.Data.Common.EntitySql.CqlParser.yyerror(String s) at System.Data.Common.EntitySql.CqlParser.yyparse() at System.Data.Common.EntitySql.CqlParser.Parse(String query) at System.Data.Common.EntitySql.CqlQuery.Parse(String query, ParserOptions parserOptions) at System.Data.Common.EntitySql.CqlQuery.Compile(String query, Perspective perspective, ParserOptions parserOptions, Dictionary`2 parameters, Dictionary`2 variables, Boolean validateTree) at System.Data.EntityClient.EntityCommand.MakeCommandTree() at System.Data.EntityClient.EntityCommand.CreateCommandDefinition() at System.Data.EntityClient.EntityCommand.TryGetEntityCommandDefinitionFromQueryCache(EntityCommandDefinition& entityCommandDefinition) at System.Data.EntityClient.EntityCommand.GetCommandDefinition() at System.Data.EntityClient.EntityCommand.InnerPrepare() at System.Data.EntityClient.EntityCommand.ExecuteReader(CommandBehavior behavior) at System.Data.EntityClient.EntityCommand.ExecuteScalar[T_Result](Func`2 resultSelector) It's seem to be a syntax error, but I can't figure where is the problem and how to resolve it. The entityConnection is ok because I can use any entities generated with EF. I tried with another simple command, but it throw another exception : DbCommand command = db.Connection.CreateCommand(); command.CommandText = "SELECT COUNT(Id) From OtherTable;"; int result = (int)command.ExecuteScalar(); And I got this error, witch is not the same, but may help : System.Data.EntitySqlException: 'Groupe' could not be resolved in the current scope or context. Make sure that all referenced variables are in scope, that required schemas are loaded, and that namespaces are referenced correctly., near simple identifier, line 1, column 23. at System.Data.Common.EntitySql.CqlErrorHelper.ReportIdentifierError(Expr expr, SemanticResolver sr) at System.Data.Common.EntitySql.SemanticAnalyzer.ConvertIdentifier(Expr expr, SemanticResolver sr) at System.Data.Common.EntitySql.SemanticAnalyzer.Convert(Expr astExpr, SemanticResolver sr) at System.Data.Common.EntitySql.SemanticAnalyzer.ProcessAliasedFromClauseItem(AliasExpr aliasedExpr, SemanticResolver sr) at System.Data.Common.EntitySql.SemanticAnalyzer.ProcessFromClauseItem(FromClauseItem fromClauseItem, SemanticResolver sr) at System.Data.Common.EntitySql.SemanticAnalyzer.ProcessFromClause(FromClause fromClause, SemanticResolver sr) at System.Data.Common.EntitySql.SemanticAnalyzer.ConvertQuery(Expr expr, SemanticResolver sr) at System.Data.Common.EntitySql.SemanticAnalyzer.Convert(Expr astExpr, SemanticResolver sr) at System.Data.Common.EntitySql.SemanticAnalyzer.ConvertRootExpression(Expr astExpr, SemanticResolver sr) at System.Data.Common.EntitySql.SemanticAnalyzer.ConvertGeneralExpression(Expr astExpr, SemanticResolver sr) at System.Data.Common.EntitySql.CqlQuery.AnalyzeSemantics(Expr astExpr, Perspective perspective, ParserOptions parserOptions, Dictionary`2 parameters, Dictionary`2 variables) at System.Data.Common.EntitySql.CqlQuery.Compile(String query, Perspective perspective, ParserOptions parserOptions, Dictionary`2 parameters, Dictionary`2 variables, Boolean validateTree) at System.Data.EntityClient.EntityCommand.MakeCommandTree() at System.Data.EntityClient.EntityCommand.CreateCommandDefinition() at System.Data.EntityClient.EntityCommand.TryGetEntityCommandDefinitionFromQueryCache(EntityCommandDefinition& entityCommandDefinition) at System.Data.EntityClient.EntityCommand.GetCommandDefinition() at System.Data.EntityClient.EntityCommand.InnerPrepare() at System.Data.EntityClient.EntityCommand.ExecuteReader(CommandBehavior behavior) at System.Data.EntityClient.EntityCommand.ExecuteScalar[T_Result](Func`2 resultSelector)

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  • How to remove the Firefox default homepage?

    - by user31788
    Hi, I am using Win 7 64 bit with Firefox as my web browser. Whenever I double click on the FF icon to open my firefox, there would be a chinese website, loading as a tab on my FF. I have checked on my setting for startup homepage for FF under the Tools > Options, it was set to Google as my default page. Can anyone please advise how can I remove the disturbing chinese website from loading on my ff everytime I open my firefox? Thank you very much.

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  • How can I fix a computer that blue screens before Windows starts?

    - by Julio
    I have a Dell Inspiron running Windows 7 that keeps getting blue screens of death. At first, the computer slowed down so much it was unusable. After some time, it wouldn't even load Windows anymore; the machine just started going straight to a BSOD after the starting Windows logo. I have tried loading the reset disc, but it just takes me to a loading lobby and never advances. I don't need the files on the computer, but I do need the machine for school. What can I do?

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  • Can't edit an account in MySQL Administrator on OS X

    - by Wavy Crab
    I'm running MySQL 5.5.20 on OS X 10.6.8. Using MySQL Administrator 1.2.12 (the latest) I am unable to edit any accounts. After successfully connecting to the database in MySQL Administrator, I go the Account tab, expand a user, and it just says "Loading...". It will stay on "Loading..." indefinitely. The symptoms are almost identical to user's experience and this MySQL bug from 2006, which has since been closed (fixed?). If I create a user and grant permissions to a schema, I get the error "Could not save changes to the use", which came up in 2005 as a bug (now closed). How do I edit MySQL accounts using MySQL Administrator?

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  • Output php mail calls to log file

    - by Tom McQuarrie
    This question relates to the question found here: Find the php script thats sending mails Trying to do the exact same thing but can't get the log to output what I need. Not too experienced with serverfault and ideally I'd post my followup on the original question, or PM adam to see if he ever found a solution, but looks as though server fault doesn't work that way. I can post an "answer" but that's definitely not what this is. I have a script located at /usr/local/bin/sendmail-php-logged, with the following: #!/bin/sh logger -p mail.info sendmail-php: site=${HTTP_HOST}, client=${REMOTE_ADDR}, script=${SCRIPT_NAME}, filename=${SCRIPT_FILENAME}, docroot=${DOCUMENT_ROOT}, pwd=${PWD}, uid=${UID}, user=$(whoami) /usr/sbin/sendmail -t -i $* This is logging to /var/log/maillog, but as Adam mentions in his question, none of the server variables work. Output I'm getting is: Oct 4 12:16:21 fluke logger: sendmail-php: site=, client=, script=, filename=, docroot=, pwd=/var/www/html/aro_chroot/sites/arocms, uid=48, user=apache Oct 4 12:16:21 fluke logger: sendmail-php: site=, client=, script=, filename=, docroot=, pwd=/var/www/html/aro_chroot/sites/arocms, uid=48, user=apache Oct 4 12:17:03 fluke logger: sendmail-php: site=, client=, script=, filename=, docroot=, pwd=/var/www/html/aro_chroot/sites/arocms, uid=48, user=apache Oct 4 12:17:05 fluke logger: sendmail-php: site=, client=, script=, filename=, docroot=, pwd=/root, uid=0, user=root Oct 4 12:17:11 fluke logger: sendmail-php: site=, client=, script=, filename=, docroot=, pwd=/var/www/html/aro_chroot/sites/arocms, uid=48, user=apache Oct 4 12:17:14 fluke logger: sendmail-php: site=, client=, script=, filename=, docroot=, pwd=/root, uid=0, user=root Oct 4 12:17:29 fluke logger: sendmail-php: site=, client=, script=, filename=, docroot=, pwd=/root, uid=0, user=root Oct 4 12:17:41 fluke logger: sendmail-php: site=, client=, script=, filename=, docroot=, pwd=/root, uid=0, user=root User ID, current user, and pwd are all working, probably because they're globally accessible script resources, and not specific to PHP, like all the others are. I've tried using other server variables as per labradort's instructions, but no joy. Here's some sample tests: logger -p mail.info sendmail-php SCRIPT_NAME: ${SCRIPT_NAME} logger -p mail.info sendmail-php SCRIPT_FILENAME: ${SCRIPT_FILENAME} logger -p mail.info sendmail-php PATH_INFO: ${PATH_INFO} logger -p mail.info sendmail-php PHP_SELF: ${PHP_SELF} logger -p mail.info sendmail-php DOCUMENT_ROOT: ${DOCUMENT_ROOT} logger -p mail.info sendmail-php REMOTE_ADDR: ${REMOTE_ADDR} logger -p mail.info sendmail-php SCRIPT_NAME: $SCRIPT_NAME logger -p mail.info sendmail-php SCRIPT_FILENAME: $SCRIPT_FILENAME logger -p mail.info sendmail-php PATH_INFO: $PATH_INFO logger -p mail.info sendmail-php PHP_SELF: $PHP_SELF logger -p mail.info sendmail-php DOCUMENT_ROOT: $DOCUMENT_ROOT logger -p mail.info sendmail-php REMOTE_ADDR: $REMOTE_ADDR And the output: Oct 4 12:58:02 fluke logger: sendmail-php SCRIPT_NAME: Oct 4 12:58:02 fluke logger: sendmail-php SCRIPT_FILENAME: Oct 4 12:58:02 fluke logger: sendmail-php PATH_INFO: Oct 4 12:58:02 fluke logger: sendmail-php PHP_SELF: Oct 4 12:58:02 fluke logger: sendmail-php DOCUMENT_ROOT: Oct 4 12:58:02 fluke logger: sendmail-php REMOTE_ADDR: Oct 4 12:58:02 fluke logger: sendmail-php SCRIPT_NAME: Oct 4 12:58:02 fluke logger: sendmail-php SCRIPT_FILENAME: Oct 4 12:58:02 fluke logger: sendmail-php PATH_INFO: Oct 4 12:58:02 fluke logger: sendmail-php PHP_SELF: Oct 4 12:58:02 fluke logger: sendmail-php DOCUMENT_ROOT: Oct 4 12:58:02 fluke logger: sendmail-php REMOTE_ADDR: I'm running php 5.3.10. Unfortunately register_globals is on, for compatibility with legacy systems, but you wouldn't think that would cause the environment variables to stop working. If someone can give me some hints as to why this might not be working I'll be a very happy man :)

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  • Filezilla/Puttygen doesn't recognize private key file

    - by devzoner
    I have generated a key for an Ubuntu Virtual Machine running on Azure Cloud Services http://www.windowsazure.com/en-us/manage/linux/how-to-guides/ssh-into-linux/ openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout myPrivateKey.key -out myCert.pem When loading the private key into Filezilla, it asks me to convert the format, however, when converting the key it fails, the same happens with puttygen from linux console, using this: puttygen myPrivateKey.key -o myKey.ppk In both cases I have the following error: puttygen: error loading `myPrivateKey.key': unrecognised key type By the way, this key doesn't have a passphrase. I found an old thread about it, but I'm using 0.6.3 version which is newer than what this thread recommends: http://fixunix.com/ssh/541874-puttygen-unable-import-openssh-key.html I've managed to solve this issue by using another gui client Fugu for Mac, but one of my co-worker uses windows and I still have to figure this out. Since Filezilla is the de-facto ftp client, I thought it would be easier to solve it there. Thanks

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  • Preloading Winforms using a Stack and Hidden Form

    - by msarchet
    I am currently working on a project where we have a couple very control heavy user controls that are being used inside a MDI Controller. This is a Line of Business app and it is very data driven. The problem that we were facing was the aforementioned controls would load very very slowly, we dipped our toes into the waters of multi-threading for the control loading but that was not a solution for a plethora of reasons. Our solution to increasing the performance of the controls ended up being to 'pre-load' the forms onto a hidden window, create a stack of the existing forms, and pop off of the stack as the user requested a form. Now the current issue that I'm seeing that will arise as we push this 'fix' out to our testers, and the ultimately our users is this: Currently the 'hidden' window that contains the preloaded forms is visible in task manager, and can be shut down thus causing all of the controls to be lost. Then you have to create them on the fly losing the performance increase. Secondly, when the user uses up the stack we lose the performance increase (current solution to this is discussed below). For the first problem, is there a way to hide this window from task manager, perhaps by creating a parent form that encapsulates both the main form for the program and the hidden form? Our current solution to the second problem is to have an inactivity timer that when it fires checks the stacks for the forms, and loads a new form onto the stack if it isn't full. However this still has the potential of causing a hang in the UI while it creates the forms. A possible solutions for this would be to put 'used' forms back onto the stack, but I feel like there may be a better way. EDIT: For control design clarification From the comments I have realized there is a lack of clarity on what exactly the control is doing. Here is a detailed explanation of one of the controls. I have defined for this control loading time as the time it takes from when a user performs an action that would open a control, until the time a control is accessible to be edited. The control is for entering Prescriptions for a patient in the system, it has about 5 tabbed groups with a total of about 180 controls. The user selects to open a new Prescription control from inside the main program, this control is loaded into the MDI Child area of the Main Form (which is a DevExpress Ribbon Control). From the time the user clicks New (or loads an existing record) until the control is visible. The list of actions that happens in the program is this: The stack is checked for the existence of a control. If the control exists it is popped off of the stack. The control is rendered on screen. This is what takes 2 seconds The control then is populated with a blank object, or with existing data. The control is ready to use. The average percentage of loading time, across about 10 different machines, with different hardware the control rendering takes about 85 - 95 percent of the control loading time. Without using the stack the control takes about 2 seconds to load, with the stack it takes about .8 seconds, this second time is acceptable. I have looked at Henry's link and I had previously already implemented the applicable suggestions. Again I re-iterate my question as What is the best method to move controls to and from the stack with as little UI interruption as possible?

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  • Windows 7 won't load unless other harddrives "disconnect"ed in UEFI shell

    - by lmz
    I have three disks, one GPT partitioned containing Windows 7 and Debian, the other MBR partitioned containing CentOS, and the other one MBR partitioned, empty. It used to work (loading Windows boot manager using rEFIt) but now after installing CentOS and OpenIndiana on the second drive, Windows won't boot. The logo is displayed briefly and then a text mode scrollbar "Loading files", then back to the rEFIt menu. The only thing that makes it work is if I drop into the UEFI shell and run disconnect XX where XX is the device handle of the other hard drives (obtained from running devices). This makes me think that the bootloader is getting confused about where the Windows partition is. Is there any information on how the Windows UEFI boot loader finds the Windows partition, or is there any logging I can turn on to help troubleshoot this issue?

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  • Wordpress site on EC2 instance suddenly superslow

    - by Emil
    Set up a wordpress page the other day following this guide. The site was up and running, loading quickly and all was well, until today. Suddenly, loading the site takes forever and doesn't even work properly, the page shows up in an incomplete fashion. I tried rebooting the instance but that didn't help. The only actions I've taken on the server is to create an elastic IP, and to point a domainname to that IP. But I don't see how that could've slowed down the page. Any thoughts on what could have caused this and on a solution to the problem?

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  • Load website and fill form from the command line

    - by Martin Scharrer
    Using the Linux command line (Bash shell) I like to load a specific website in my browser (normally Firefox, but other one would be ok as well as long it runs under Linux) and fill a pre-defined form with some data. Actually, this should run from a Makefile. Most of the form data is static and will be stored as variables in the Makefile, just some fields are to be filled manually before manually sending the form. I know how to load the website in question from the command line using: firefox <URL> But there seems no possibility to fill the form automatically with variables given on the command line. Is there a plugin, executable or JavaScript which allows me to do this? Any suggestions and hints are welcome. I don't mind coding some JavaScript.

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  • Changing Windows public folder in batch script.

    - by Angus
    I've installed Steam on an external hard drive so I can play games on different computers by just moving the drive around. Since save games are often saved in My Documents or AppData, but I want them to move with the external hard drive, I wrote a batch file that sets environment variables before starting steam. setocal set USERPROFILE=%EXTERNAL_LETTER%\Profile\Me set APPDATA=%USERPROFILE%\AppData\Roaming ... start %TARGETAPP% endlocal I'm not sure if this is the right way to do this on Windows, but it seems to work. However, one game saves its games in the Shared Documents folder. I've tried setting %PUBLIC% and %ALLUSERSPROFILE% but that does not seem to affect where the game looks. Is it possible to make this one program use a different Shared Documents folder, either by environment variables or some other means? The change in Shared Documents should only affect the one program, I do not want it to be a permanent or system wide change to Windows.

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  • Weirdness After Reinstall The Windows Operating System

    - by Eka Anggraini
    I want to ask, and ask advice from you guys. I have reinstall my OS and successful, I'm turn off the restart a few times is fine .. Later a few hours later, when I turn it on, a sudden there was an error : Windows could not start because the following file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SYSTEM You can attempt to repair this file by starting Windows Setup using the original Setup CD-ROM Select 'R' at the first screen to start repair. So I intend to repair, reinstall all again .. I enter cd windows : press any key .. with blue background text below: Setup is loading files (windows executive) Setup is loading files (hardware abstraction layer) Then I was waiting until half an hour, and no changes, I repeated the process several times is also nil. Please advice and solutions about the problem where? Hardware / cd Windows ?

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  • Linux Mint does not start after renaming home directory

    - by RUBY
    I am new to linux and was just trying to rename the only directory in home from rk to rhk. I messed up the whole thing and the settings. Created some new thing named rhk which I can't remember as it got all messed up and Now I am getting nothing after Linux Mint 10(julia) boots up - no start menu, no panel, no taskbar nothing. I tried to work in the recovery mode and got some(downloaded) 216mb of something(in the repair broken packages) hoping that it might help but didn't help. Moreover whenver I have booted in it shows messages like Could not update ICEauthority file /home/rk./.ICEauthority there is a problem with the configuration server. (usr/lib/libconfig24/gconfsanitycheck2 exited with status 256) The panel encountered a problem while loading "OAFIID: GNOME_mintMenu" The panel encountered a problem while loading "OAFIID: GNOME_IndicatorApplet" Naulitis could not create the following reqiured folders: /home/rk/Desktop, /home/rk/. Naulitis Moreover Alt+F2 gives Run application or run with file and nothing seems to be working.

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  • No package rrdtool-perl available

    - by Pentium10
    On a CentOS release 5.10 (Final) I am trying to install rrdtool to get RRDs.pm but I have no luck. yum install rrdtool-perl Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * rpmforge: mirror.team-cymru.org Excluding Packages in global exclude list Finished Setting up Install Process No package rrdtool-perl available. Nothing to do I tried also librrds-perl but that was not found either. 2. I tried: yum whatprovides "*/RRDs.pm" Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * rpmforge: mirror.team-cymru.org Excluding Packages in global exclude list Finished cpanel-perl-514-Log-Log4perl-1.37-1.cp1136.x86_64 : CPAN module - Log4j implementation for Perl Repo : installed Matched from: Filename : /usr/local/cpanel/3rdparty/perl/514/lib64/perl5/cpanel_lib/Log/Log4perl/Appender/RRDs.pm cpanel-perl-514-RRDs-v1.4.7-1.cp1136.x86_64 : CPAN module - unknown Repo : installed Matched from: Filename : /usr/local/cpanel/3rdparty/perl/514/lib64/perl5/cpanel_lib/x86_64-linux-64int/RRDs.pm then I tried installing but I got: No package cpanel-perl available and the variants (tried with full name, tried both repos listed)

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  • Network keeps disconnecting - Repairing solves it. Router configuration

    - by Joao Carlos
    My network connection keeps going insane, it will keep normal applications connected, like TeamViewer and MSN, but webpages will stop loading (Problem loading page). Everything looks connected and works like a charm, but webpages and new connections wont work. If I press "Repair" in the network connections to restart the adapter, it will work. This happens on WIRED and WIRELESS connections, both on Windows and on MacOSx. I have had this for years (different computers, routers, cities), but I never figured it out. I learn to live with it, but, I think theres probably a solution. What must I be doing wrong if this keeps happening? You guys have same thing?

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  • Error in python - don't understand

    - by Jasper
    Hi, I'm creating a game, and am quite new to Python generally. I created a function 'descriptionGenerator()' which generates a description for characters and objects either randomly or using variables passed to it. It seemed to be working, but every now and then it wouldn't work correctly. So i placed it in a loop, and it never seems to be able to complete the loop without one of the iterations having this problem. The code is as follows: #+------------------------------------------+ #| Name: bitsandpieces.py | #| A module for the 'Europa I' game | #| created for the Game Making Competition | #| | #| Date Created/Modified: | #| 3/4/10 | 3/4/10 | #+------------------------------------------+ # Import the required modules # Import system modules: import time import random # Import 3rd party modules: # Import game modules: # Define the 'descriptionGenerator()' function def descriptionGenerator(descriptionVariables): descriptionVariableSize = len(descriptionVariables) if descriptionVariables[0] == 'char': # If there is only one variable ('char'), create a random description if descriptionVariableSize == 1: # Define choices for descriptionVariables to be generated from gender_choices = ['male', 'female'] hair_choices = ['black', 'red', 'blonde', 'grey', 'brown', 'blue'] hair_choices2 = ['long', 'short', 'cropped', 'curly'] size_choices = ['tubby', 'thin', 'fat', 'almost twig-like'] demeanour_choices = ['glowering', 'bright', 'smiling', 'sombre', 'intelligent'] impression_choices = ['likeable', 'unlikeable', 'dangerous', 'annoying', 'afraid'] # Define description variables gender = random.choice(gender_choices) height = str(float('0.' + str(random.randint(1, 9))) + float(random.randint(1, 2))) if float(height) > 1.8: height_string = 'tall' if float(height) > 2: height_string = 'very tall' elif float(height) < 1.8 and float(height) > 1.5: height_string = 'average' elif float(height) < 1.5: height_string = 'short' if float(height) < 1.3: height_string = 'very short' hair = random.choice(hair_choices2) + ' ' + random.choice(hair_choices) size = random.choice(size_choices) demeanour = random.choice(demeanour_choices) impression = random.choice(impression_choices) # Collect description variables in list 'randomDescriptionVariables' randomDescriptionVariables = ['char', gender, height, height_string, hair, size, demeanour, impression] # Generate description using the 'descriptionGenerator' function descriptionGenerator(randomDescriptionVariables) # Generate the description of a character using the variables passed to the function elif descriptionVariableSize == 8: if descriptionVariables[1] == 'male': if descriptionVariables[7] != 'afraid': print """A %s man, about %s m tall. He has %s hair and is %s. He is %s and you get the impression that he is %s.""" %(descriptionVariables[3], descriptionVariables[2], descriptionVariables[4], descriptionVariables[5], descriptionVariables[6], descriptionVariables[7]) elif descriptionVariables[7] == 'afraid': print """A %s man, about %s m tall. He has %s hair and is %s. He is %s.\nYou feel that you should be %s of him.""" %(descriptionVariables[3], descriptionVariables[2], descriptionVariables[4], descriptionVariables[5], descriptionVariables[6], descriptionVariables[7]) elif descriptionVariables[1] == 'female': if descriptionVariables[7] != 'afraid': print """A %s woman, about %s m tall. She has %s hair and is %s. She is %s and you get the impression that she is %s.""" %(descriptionVariables[3], descriptionVariables[2], descriptionVariables[4], descriptionVariables[5], descriptionVariables[6], descriptionVariables[7]) elif descriptionVariables[7] == 'afraid': print """A %s woman, about %s m tall. She has %s hair and is %s. She is %s.\nYou feel that you should be %s of her.""" %(descriptionVariables[3], descriptionVariables[2], descriptionVariables[4], descriptionVariables[5], descriptionVariables[6], descriptionVariables[7]) else: pass elif descriptionVariables[0] == 'obj': # Insert code here 2 deal with object stuff pass print print myDescriptionVariables = ['char'] i = 0 while i < 30: print print print descriptionGenerator(myDescriptionVariables) i = i + 1 time.sleep(10) When it fails to properly execute it says this: Traceback (most recent call last): File "/Users/Jasper/Development/Programming/MyProjects/Game Making Challenge/Europa I/Code/Code 2.0/bitsandpieces.py", line 79, in <module> descriptionGenerator(myDescriptionVariables) File "/Users/Jasper/Development/Programming/MyProjects/Game Making Challenge/Europa I/Code/Code 2.0/bitsandpieces.py", line 50, in descriptionGenerator randomDescriptionVariables = ['char', gender, height, height_string, hair, size, demeanour, impression] UnboundLocalError: local variable 'height_string' referenced before assignment Thanks for any help with this

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  • Need help on awk/sed/ perl pattern with regex / grep

    - by Jayakumar K
    Sample file output from grep file1:my $dbh = DBI->connect("dbi:mysql:$database_name", $DB_USER, $DB_PASSWD) file2:($dbc,$rc) = mysql_connect($mysql_host,$mysql_user,$mysql_password); The awk pattern should get values databasename, DB_USER And DB_PASSWD from line 1 and mysql_host,mysql_user and mysql_password from line 2 i.e all variables inside the function. Then it should search for the declaration of that variable in file before : (semicolon) ex: databasename in file1 may be $databasename = "dbweb" ; ex: mysql_user in file2 may be $mysql_user="root" ; Result: It should display variable declarations of all 6 variables along with filenames file2:$mysql_host = "db1"; file2:$mysql_user = "root"; file1:$DB_USER = 'user';

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