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• SQL SERVER – Guest Post – Jonathan Kehayias – Wait Type – Day 16 of 28

  - by pinaldave

  Jonathan Kehayias (Blog | Twitter) is a MCITP Database Administrator and Developer, who got started in SQL Server in 2004 as a database developer and report writer in the natural gas industry. After spending two and a half years working in TSQL, in late 2006, he transitioned to the role of SQL Database Administrator. His primary passion is performance tuning, where he frequently rewrites queries for better performance and performs in depth analysis of index implementation and usage. Jonathan blogs regularly on SQLBlog, and was a coauthor of Professional SQL Server 2008 Internals and Troubleshooting. On a personal note, I think Jonathan is extremely positive person. In every conversation with him I have found that he is always eager to help and encourage. Every time he finds something needs to be approved, he has contacted me without hesitation and guided me to improve, change and learn. During all the time, he has not lost his focus to help larger community. I am honored that he has accepted to provide his views on complex subject of Wait Types and Queues. Currently I am reading his series on Extended Events. Here is the guest blog post by Jonathan: SQL Server troubleshooting is all about correlating related pieces of information together to indentify where exactly the root cause of a problem lies. In my daily work as a DBA, I generally get phone calls like, “So and so application is slow, what’s wrong with the SQL Server.” One of the funny things about the letters DBA is that they go so well with Default Blame Acceptor, and I really wish that I knew exactly who the first person was that pointed that out to me, because it really fits at times. A lot of times when I get this call, the problem isn’t related to SQL Server at all, but every now and then in my initial quick checks, something pops up that makes me start looking at things further. The SQL Server is slow, we see a number of tasks waiting on ASYNC_IO_COMPLETION, IO_COMPLETION, or PAGEIOLATCH_* waits in sys.dm_exec_requests and sys.dm_exec_waiting_tasks. These are also some of the highest wait types in sys.dm_os_wait_stats for the server, so it would appear that we have a disk I/O bottleneck on the machine. A quick check of sys.dm_io_virtual_file_stats() and tempdb shows a high write stall rate, while our user databases show high read stall rates on the data files. A quick check of some performance counters and Page Life Expectancy on the server is bouncing up and down in the 50-150 range, the Free Page counter consistently hits zero, and the Free List Stalls/sec counter keeps jumping over 10, but Buffer Cache Hit Ratio is 98-99%. Where exactly is the problem? In this case, which happens to be based on a real scenario I faced a few years back, the problem may not be a disk bottleneck at all; it may very well be a memory pressure issue on the server. A quick check of the system spec’s and it is a dual duo core server with 8GB RAM running SQL Server 2005 SP1 x64 on Windows Server 2003 R2 x64. Max Server memory is configured at 6GB and we think that this should be enough to handle the workload; or is it? This is a unique scenario because there are a couple of things happening inside of this system, and they all relate to what the root cause of the performance problem is on the system. If we were to query sys.dm_exec_query_stats for the TOP 10 queries, by max_physical_reads, max_logical_reads, and max_worker_time, we may be able to find some queries that were using excessive I/O and possibly CPU against the system in their worst single execution. We can also CROSS APPLY to sys.dm_exec_sql_text() and see the statement text, and also CROSS APPLY sys.dm_exec_query_plan() to get the execution plan stored in cache. Ok, quick check, the plans are pretty big, I see some large index seeks, that estimate 2.8GB of data movement between operators, but everything looks like it is optimized the best it can be. Nothing really stands out in the code, and the indexing looks correct, and I should have enough memory to handle this in cache, so it must be a disk I/O problem right? Not exactly! If we were to look at how much memory the plan cache is taking by querying sys.dm_os_memory_clerks for the CACHESTORE_SQLCP and CACHESTORE_OBJCP clerks we might be surprised at what we find. In SQL Server 2005 RTM and SP1, the plan cache was allowed to take up to 75% of the memory under 8GB. I’ll give you a second to go back and read that again. Yes, you read it correctly, it says 75% of the memory under 8GB, but you don’t have to take my word for it, you can validate this by reading Changes in Caching Behavior between SQL Server 2000, SQL Server 2005 RTM and SQL Server 2005 SP2. In this scenario the application uses an entirely adhoc workload against SQL Server and this leads to plan cache bloat, and up to 4.5GB of our 6GB of memory for SQL can be consumed by the plan cache in SQL Server 2005 SP1. This in turn reduces the size of the buffer cache to just 1.5GB, causing our 2.8GB of data movement in this expensive plan to cause complete flushing of the buffer cache, not just once initially, but then another time during the queries execution, resulting in excessive physical I/O from disk. Keep in mind that this is not the only query executing at the time this occurs. Remember the output of sys.dm_io_virtual_file_stats() showed high read stalls on the data files for our user databases versus higher write stalls for tempdb? The memory pressure is also forcing heavier use of tempdb to handle sorting and hashing in the environment as well. The real clue here is the Memory counters for the instance; Page Life Expectancy, Free List Pages, and Free List Stalls/sec. The fact that Page Life Expectancy is fluctuating between 50 and 150 constantly is a sign that the buffer cache is experiencing constant churn of data, once every minute to two and a half minutes. If you add to the Page Life Expectancy counter, the consistent bottoming out of Free List Pages along with Free List Stalls/sec consistently spiking over 10, and you have the perfect memory pressure scenario. All of sudden it may not be that our disk subsystem is the problem, but is instead an innocent bystander and victim. Side Note: The Page Life Expectancy counter dropping briefly and then returning to normal operating values intermittently is not necessarily a sign that the server is under memory pressure. The Books Online and a number of other references will tell you that this counter should remain on average above 300 which is the time in seconds a page will remain in cache before being flushed or aged out. This number, which equates to just five minutes, is incredibly low for modern systems and most published documents pre-date the predominance of 64 bit computing and easy availability to larger amounts of memory in SQL Servers. As food for thought, consider that my personal laptop has more memory in it than most SQL Servers did at the time those numbers were posted. I would argue that today, a system churning the buffer cache every five minutes is in need of some serious tuning or a hardware upgrade. Back to our problem and its investigation: There are two things really wrong with this server; first the plan cache is excessively consuming memory and bloated in size and we need to look at that and second we need to evaluate upgrading the memory to accommodate the workload being performed. In the case of the server I was working on there were a lot of single use plans found in sys.dm_exec_cached_plans (where usecounts=1). Single use plans waste space in the plan cache, especially when they are adhoc plans for statements that had concatenated filter criteria that is not likely to reoccur with any frequency.  SQL Server 2005 doesn’t natively have a way to evict a single plan from cache like SQL Server 2008 does, but MVP Kalen Delaney, showed a hack to evict a single plan by creating a plan guide for the statement and then dropping that plan guide in her blog post Geek City: Clearing a Single Plan from Cache. We could put that hack in place in a job to automate cleaning out all the single use plans periodically, minimizing the size of the plan cache, but a better solution would be to fix the application so that it uses proper parameterized calls to the database. You didn’t write the app, and you can’t change its design? Ok, well you could try to force parameterization to occur by creating and keeping plan guides in place, or we can try forcing parameterization at the database level by using ALTER DATABASE <dbname> SET PARAMETERIZATION FORCED and that might help. If neither of these help, we could periodically dump the plan cache for that database, as discussed as being a problem in Kalen’s blog post referenced above; not an ideal scenario. The other option is to increase the memory on the server to 16GB or 32GB, if the hardware allows it, which will increase the size of the plan cache as well as the buffer cache. In SQL Server 2005 SP1, on a system with 16GB of memory, if we set max server memory to 14GB the plan cache could use at most 9GB  [(8GB*.75)+(6GB*.5)=(6+3)=9GB], leaving 5GB for the buffer cache.  If we went to 32GB of memory and set max server memory to 28GB, the plan cache could use at most 16GB [(8*.75)+(20*.5)=(6+10)=16GB], leaving 12GB for the buffer cache. Thankfully we have SQL Server 2005 Service Pack 2, 3, and 4 these days which include the changes in plan cache sizing discussed in the Changes to Caching Behavior between SQL Server 2000, SQL Server 2005 RTM and SQL Server 2005 SP2 blog post. In real life, when I was troubleshooting this problem, I spent a week trying to chase down the cause of the disk I/O bottleneck with our Server Admin and SAN Admin, and there wasn’t much that could be done immediately there, so I finally asked if we could increase the memory on the server to 16GB, which did fix the problem. It wasn’t until I had this same problem occur on another system that I actually figured out how to really troubleshoot this down to the root cause.  I couldn’t believe the size of the plan cache on the server with 16GB of memory when I actually learned about this and went back to look at it. SQL Server is constantly telling a story to anyone that will listen. As the DBA, you have to sit back and listen to all that it’s telling you and then evaluate the big picture and how all the data you can gather from SQL about performance relate to each other. One of the greatest tools out there is actually a free in the form of Diagnostic Scripts for SQL Server 2005 and 2008, created by MVP Glenn Alan Berry. Glenn’s scripts collect a majority of the information that SQL has to offer for rapid troubleshooting of problems, and he includes a lot of notes about what the outputs of each individual query might be telling you. When I read Pinal’s blog post SQL SERVER – ASYNC_IO_COMPLETION – Wait Type – Day 11 of 28, I noticed that he referenced Checking Memory Related Performance Counters in his post, but there was no real explanation about why checking memory counters is so important when looking at an I/O related wait type. I thought I’d chat with him briefly on Google Talk/Twitter DM and point this out, and offer a couple of other points I noted, so that he could add the information to his blog post if he found it useful.  Instead he asked that I write a guest blog for this. I am honored to be a guest blogger, and to be able to share this kind of information with the community. The information contained in this blog post is a glimpse at how I do troubleshooting almost every day of the week in my own environment. SQL Server provides us with a lot of information about how it is running, and where it may be having problems, it is up to us to play detective and find out how all that information comes together to tell us what’s really the problem. This blog post is written by Jonathan Kehayias (Blog | Twitter). Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: MVP, Pinal Dave, PostADay, Readers Contribution, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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• SmoothLife Is a Super Smooth Version of Conway’s Game of Life [Video]

  - by Jason Fitzpatrick

  What happens if you change cellular automaton program Game of Life to use floating point values instead of integers? You end up with SmoothLife, a fluid and organic growth simulator. SmoothLife is a family of rules created by Stephan Rafler. It was designed as a continuous version of Conway’s Game of Life – using floating point values instead of integers. This rule is SmoothLifeL which supports many interesting phenomena such as gliders that can travel in any direction, rotating pairs of gliders, wickstretchers and the appearance of elastic tension in the ‘cords’ that join the blobs. You can check out the paper outlining how SmoothLife works here and then grab the source code to run your own simulation here. [via Boing Boing] HTG Explains: What is the Windows Page File and Should You Disable It? How To Get a Better Wireless Signal and Reduce Wireless Network Interference How To Troubleshoot Internet Connection Problems

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• What are functional-programming ways of implementing Conway's Game of Life

  - by George Mauer

  I recently implemented for fun Conway's Game of Life in Javascript (actually coffeescript but same thing). Since javascript can be used as a functional language I was trying to stay to that end of the spectrum. I was not happy with my results. I am a fairly good OO programmer and my solution smacked of same-old-same-old. So long question short: what is the (pseudocode) functional style of doing it? Here is Pseudocode for my attempt: class Node update: (board) -> get number_of_alive_neighbors from board get this_is_alive from board if this_is_alive and number_of_alive_neighbors < 2 then die if this_is_alive and number_of_alive_neighbors > 3 then die if not this_is_alive and number_of_alive_neighbors == 3 then alive class NodeLocations at: (x, y) -> return node value at x,y of: (node) -> return x,y of node class Board getNeighbors: (node) -> use node_locations to check 8 neighbors around node and return count nodes = for 1..100 new Node state = new NodeState(nodes) locations = new NodeLocations(nodes) board = new Board(locations, state) executeRound: state = clone state accumulated_changes = for n in nodes n.update(board) apply accumulated_changes to state board = new Board(locations, state)

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• Damian Conway on Perl and its future

  <b>O'Reilly GMT:</b> "We often hear people saying that Perl is dead. I assume that you don't agree, but what do you say to people who try to tell you that?"

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• Conway's Game of Life - C++ and Qt

  - by Jeff Bridge

  I've done all of the layouts and have most of the code written even. But, I'm stuck in two places. 1) I'm not quite sure how to set up the timer. Am I using it correctly in the gridwindow class? And, am I used the timer functions/signals/slots correctly with the other gridwindow functions. 2) In GridWindow's timerFired() function, I'm having trouble checking/creating the vector-vectors. I wrote out in the comments in that function exactly what I am trying to do. Any help would be much appreciated. main.cpp // Main file for running the grid window application. #include <QApplication> #include "gridwindow.h" //#include "timerwindow.h" #include <stdexcept> #include <string> #include <fstream> #include <sstream> #include <iostream> void Welcome(); // Welcome Function - Prints upon running program; outputs program name, student name/id, class section. void Rules(); // Rules Function: Prints the rules for Conway's Game of Life. using namespace std; // A simple main method to create the window class and then pop it up on the screen. int main(int argc, char *argv[]) { Welcome(); // Calls Welcome function to print student/assignment info. Rules(); // Prints Conway's Game Rules. QApplication app(argc, argv); // Creates the overall windowed application. int rows = 25, cols = 35; //The number of rows & columns in the game grid. GridWindow widget(NULL,rows,cols); // Creates the actual window (for the grid). widget.show(); // Shows the window on the screen. return app.exec(); // Goes into visual loop; starts executing GUI. } // Welcome Function: Prints my name/id, my class number, the assignment, and the program name. void Welcome() { cout << endl; cout << "-------------------------------------------------------------------------------------------------" << endl; cout << "Name/ID - Gabe Audick #7681539807" << endl; cout << "Class/Assignment - CSCI-102 Disccusion 29915: Homework Assignment #4" << endl; cout << "-------------------------------------------------------------------------------------------------" << endl << endl; } // Rules Function: Prints the rules for Conway's Game of Life. void Rules() { cout << "Welcome to Conway's Game of Life." << endl; cout << "Game Rules:" << endl; cout << "\t 1) Any living cell with fewer than two living neighbours dies, as if caused by underpopulation." << endl; cout << "\t 2) Any live cell with more than three live neighbours dies, as if by overcrowding." << endl; cout << "\t 3) Any live cell with two or three live neighbours lives on to the next generation." << endl; cout << "\t 4) Any dead cell with exactly three live neighbours becomes a live cell." << endl << endl; cout << "Enjoy." << endl << endl; } gridcell.h // A header file for a class representing a single cell in a grid of cells. #ifndef GRIDCELL_H_ #define GRIDCELL_H_ #include <QPalette> #include <QColor> #include <QPushButton> #include <Qt> #include <QWidget> #include <QFrame> #include <QHBoxLayout> #include <iostream> // An enum representing the two different states a cell can have. enum CellType { DEAD, // DEAD = Dead Cell. --> Color = White. LIVE // LIVE = Living Cell. ---> Color = White. }; /* Class: GridCell. A class representing a single cell in a grid. Each cell is implemented as a QT QFrame that contains a single QPushButton. The button is sized so that it takes up the entire frame. Each cell also keeps track of what type of cell it is based on the CellType enum. */ class GridCell : public QFrame { Q_OBJECT // Macro allowing us to have signals & slots on this object. private: QPushButton* button; // The button inside the cell that gives its clickability. CellType type; // The type of cell (DEAD or LIVE.) public slots: void handleClick(); // Callback for handling a click on the current cell. void setType(CellType type); // Cell type mutator. Calls the "redrawCell" function. signals: void typeChanged(CellType type); // Signal to notify listeners when the cell type has changed. public: GridCell(QWidget *parent = NULL); // Constructor for creating a cell. Takes parent widget or default parent to NULL. virtual ~GridCell(); // Destructor. void redrawCell(); // Redraws cell: Sets new type/color. CellType getType() const; //Simple getter for the cell type. private: Qt::GlobalColor getColorForCellType(); // Helper method. Returns color that cell should be based from its value. }; #endif gridcell.cpp #include <iostream> #include "gridcell.h" #include "utility.h" using namespace std; // Constructor: Creates a grid cell. GridCell::GridCell(QWidget *parent) : QFrame(parent) { this->type = DEAD; // Default: Cell is DEAD (white). setFrameStyle(QFrame::Box); // Set the frame style. This is what gives each box its black border. this->button = new QPushButton(this); //Creates button that fills entirety of each grid cell. this->button->setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); // Expands button to fill space. this->button->setMinimumSize(19,19); //width,height // Min height and width of button. QHBoxLayout *layout = new QHBoxLayout(); //Creates a simple layout to hold our button and add the button to it. layout->addWidget(this->button); setLayout(layout); layout->setStretchFactor(this->button,1); // Lets the buttons expand all the way to the edges of the current frame with no space leftover layout->setContentsMargins(0,0,0,0); layout->setSpacing(0); connect(this->button,SIGNAL(clicked()),this,SLOT(handleClick())); // Connects clicked signal with handleClick slot. redrawCell(); // Calls function to redraw (set new type for) the cell. } // Basic destructor. GridCell::~GridCell() { delete this->button; } // Accessor for the cell type. CellType GridCell::getType() const { return(this->type); } // Mutator for the cell type. Also has the side effect of causing the cell to be redrawn on the GUI. void GridCell::setType(CellType type) { this->type = type; redrawCell(); } // Handler slot for button clicks. This method is called whenever the user clicks on this cell in the grid. void GridCell::handleClick() { // When clicked on... if(this->type == DEAD) // If type is DEAD (white), change to LIVE (black). type = LIVE; else type = DEAD; // If type is LIVE (black), change to DEAD (white). setType(type); // Sets new type (color). setType Calls redrawCell() to recolor. } // Method to check cell type and return the color of that type. Qt::GlobalColor GridCell::getColorForCellType() { switch(this->type) { default: case DEAD: return Qt::white; case LIVE: return Qt::black; } } // Helper method. Forces current cell to be redrawn on the GUI. Called whenever the setType method is invoked. void GridCell::redrawCell() { Qt::GlobalColor gc = getColorForCellType(); //Find out what color this cell should be. this->button->setPalette(QPalette(gc,gc)); //Force the button in the cell to be the proper color. this->button->setAutoFillBackground(true); this->button->setFlat(true); //Force QT to NOT draw the borders on the button } gridwindow.h // A header file for a QT window that holds a grid of cells. #ifndef GRIDWINDOW_H_ #define GRIDWINDOW_H_ #include <vector> #include <QWidget> #include <QTimer> #include <QGridLayout> #include <QLabel> #include <QApplication> #include "gridcell.h" /* class GridWindow: This is the class representing the whole window that comes up when this program runs. It contains a header section with a title, a middle section of MxN cells and a bottom section with buttons. */ class GridWindow : public QWidget { Q_OBJECT // Macro to allow this object to have signals & slots. private: std::vector<std::vector<GridCell*> > cells; // A 2D vector containing pointers to all the cells in the grid. QLabel *title; // A pointer to the Title text on the window. QTimer *timer; // Creates timer object. public slots: void handleClear(); // Handler function for clicking the Clear button. void handleStart(); // Handler function for clicking the Start button. void handlePause(); // Handler function for clicking the Pause button. void timerFired(); // Method called whenever timer fires. public: GridWindow(QWidget *parent = NULL,int rows=3,int cols=3); // Constructor. virtual ~GridWindow(); // Destructor. std::vector<std::vector<GridCell*> >& getCells(); // Accessor for the array of grid cells. private: QHBoxLayout* setupHeader(); // Helper function to construct the GUI header. QGridLayout* setupGrid(int rows,int cols); // Helper function to constructor the GUI's grid. QHBoxLayout* setupButtonRow(); // Helper function to setup the row of buttons at the bottom. }; #endif gridwindow.cpp #include <iostream> #include "gridwindow.h" using namespace std; // Constructor for window. It constructs the three portions of the GUI and lays them out vertically. GridWindow::GridWindow(QWidget *parent,int rows,int cols) : QWidget(parent) { QHBoxLayout *header = setupHeader(); // Setup the title at the top. QGridLayout *grid = setupGrid(rows,cols); // Setup the grid of colored cells in the middle. QHBoxLayout *buttonRow = setupButtonRow(); // Setup the row of buttons across the bottom. QVBoxLayout *layout = new QVBoxLayout(); // Puts everything together. layout->addLayout(header); layout->addLayout(grid); layout->addLayout(buttonRow); setLayout(layout); } // Destructor. GridWindow::~GridWindow() { delete title; } // Builds header section of the GUI. QHBoxLayout* GridWindow::setupHeader() { QHBoxLayout *header = new QHBoxLayout(); // Creates horizontal box. header->setAlignment(Qt::AlignHCenter); this->title = new QLabel("CONWAY'S GAME OF LIFE",this); // Creates big, bold, centered label (title): "Conway's Game of Life." this->title->setAlignment(Qt::AlignHCenter); this->title->setFont(QFont("Arial", 32, QFont::Bold)); header->addWidget(this->title); // Adds widget to layout. return header; // Returns header to grid window. } // Builds the grid of cells. This method populates the grid's 2D array of GridCells with MxN cells. QGridLayout* GridWindow::setupGrid(int rows,int cols) { QGridLayout *grid = new QGridLayout(); // Creates grid layout. grid->setHorizontalSpacing(0); // No empty spaces. Cells should be contiguous. grid->setVerticalSpacing(0); grid->setSpacing(0); grid->setAlignment(Qt::AlignHCenter); for(int i=0; i < rows; i++) //Each row is a vector of grid cells. { std::vector<GridCell*> row; // Creates new vector for current row. cells.push_back(row); for(int j=0; j < cols; j++) { GridCell *cell = new GridCell(); // Creates and adds new cell to row. cells.at(i).push_back(cell); grid->addWidget(cell,i,j); // Adds to cell to grid layout. Column expands vertically. grid->setColumnStretch(j,1); } grid->setRowStretch(i,1); // Sets row expansion horizontally. } return grid; // Returns grid. } // Builds footer section of the GUI. QHBoxLayout* GridWindow::setupButtonRow() { QHBoxLayout *buttonRow = new QHBoxLayout(); // Creates horizontal box for buttons. buttonRow->setAlignment(Qt::AlignHCenter); // Clear Button - Clears cell; sets them all to DEAD/white. QPushButton *clearButton = new QPushButton("CLEAR"); clearButton->setFixedSize(100,25); connect(clearButton, SIGNAL(clicked()), this, SLOT(handleClear())); buttonRow->addWidget(clearButton); // Start Button - Starts game when user clicks. Or, resumes game after being paused. QPushButton *startButton = new QPushButton("START/RESUME"); startButton->setFixedSize(100,25); connect(startButton, SIGNAL(clicked()), this, SLOT(handleStart())); buttonRow->addWidget(startButton); // Pause Button - Pauses simulation of game. QPushButton *pauseButton = new QPushButton("PAUSE"); pauseButton->setFixedSize(100,25); connect(pauseButton, SIGNAL(clicked()), this, SLOT(handlePause())); buttonRow->addWidget(pauseButton); // Quit Button - Exits program. QPushButton *quitButton = new QPushButton("EXIT"); quitButton->setFixedSize(100,25); connect(quitButton, SIGNAL(clicked()), qApp, SLOT(quit())); buttonRow->addWidget(quitButton); return buttonRow; // Returns bottom of layout. } /* SLOT method for handling clicks on the "clear" button. Receives "clicked" signals on the "Clear" button and sets all cells to DEAD. */ void GridWindow::handleClear() { for(unsigned int row=0; row < cells.size(); row++) // Loops through current rows' cells. { for(unsigned int col=0; col < cells[row].size(); col++) { GridCell *cell = cells[row][col]; // Grab the current cell & set its value to dead. cell->setType(DEAD); } } } /* SLOT method for handling clicks on the "start" button. Receives "clicked" signals on the "start" button and begins game simulation. */ void GridWindow::handleStart() { this->timer = new QTimer(this); // Creates new timer. connect(this->timer, SIGNAL(timeout()), this, SLOT(timerFired())); // Connect "timerFired" method class to the "timeout" signal fired by the timer. this->timer->start(500); // Timer to fire every 500 milliseconds. } /* SLOT method for handling clicks on the "pause" button. Receives "clicked" signals on the "pause" button and stops the game simulation. */ void GridWindow::handlePause() { this->timer->stop(); // Stops the timer. delete this->timer; // Deletes timer. } // Accessor method - Gets the 2D vector of grid cells. std::vector<std::vector<GridCell*> >& GridWindow::getCells() { return this->cells; } void GridWindow::timerFired() { // I'm not sure how to write this code. // I want to take the original vector-vector, and also make a new, empty vector-vector of the same size. // I would then go through the code below with the original vector, and apply the rules to the new vector-vector. // Finally, I would make the new vector-vecotr the original vector-vector. (That would be one step in the simulation.) cout << cells[1][2]; /* for (unsigned int m = 0; m < original.size(); m++) { for (unsigned int n = 0; n < original.at(m).size(); n++) { unsigned int neighbors = 0; //Begin counting number of neighbors. if (original[m-1][n-1].getType() == LIVE) // If a cell next to [i][j] is LIVE, add one to the neighbor count. neighbors += 1; if (original[m-1][n].getType() == LIVE) neighbors += 1; if (original[m-1][n+1].getType() == LIVE) neighbors += 1; if (original[m][n-1].getType() == LIVE) neighbors += 1; if (original[m][n+1].getType() == LIVE) neighbors += 1; if (original[m+1][n-1].getType() == LIVE) neighbors += 1; if (original[m+1][n].getType() == LIVE) neighbors += 1; if (original[m+1][n+1].getType() == LIVE) neighbors += 1; if (original[m][n].getType() == LIVE && neighbors < 2) // Apply game rules to cells: Create new, updated grid with the roundtwo vector. roundtwo[m][n].setType(LIVE); else if (original[m][n].getType() == LIVE && neighbors > 3) roundtwo[m][n].setType(DEAD); else if (original[m][n].getType() == LIVE && (neighbors == 2 || neighbors == 3)) roundtwo[m][n].setType(LIVE); else if (original[m][n].getType() == DEAD && neighbors == 3) roundtwo[m][n].setType(LIVE); } }*/ }

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• Perl OO frameworks and program design - Moose and Conway's inside-out objects (Class::Std)

  - by Emmel

  This is more of a use-case type of question... but also generic enough to be more broadly applicable: In short, I'm working on a module that's more or less a command-line wrapper; OO naturally. Without going into too many details (unless someone wants them), there isn't a crazy amount of complexity to the system, but it did feel natural to have three or four objects in this framework. Finally, it's an open source thing I'll put out there, rather than a module with a few developers in the same firm working on it. First I implemented the OO using Class::Std, because Perl Best Practices (Conway, 2005) made a good argument for why to use inside-out objects. Full control over what attributes get accessed and so on, proper encapsulation, etc. Also his design is surprisingly simple and clever. I liked it, but then noticed that no one really uses this; in fact it seems Conway himself doesn't really recommend this anymore? So I moved to everyone's favorite, Moose. It's easy to use, although way way overkill feature-wise for what I want to do. The big, major downside is: it's got a slew of module dependencies that force users of my module to download them all. A minor downside is it's got way more functionality than I really need. What are recommendations? Inconvenience fellow developers by forcing them to use a possibly-obsolete module, or force every user of the module to download Moose and all its dependencies? Is there a third option for a proper Perl OO framework that's popular but neither of these two?

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• C++ - Conway's Game of Life & Stepping Backwards

  - by Gabe

  I was able to create a version Conway's Game of Life that either stepped forward each click, or just ran forward using a timer. (I'm doing this using Qt.) Now, I need to be able to save all previous game grids, so that I can step backwards by clicking a button. I'm trying to use a stack, and it seems like I'm pushing the old gridcells onto the stack correctly. But when I run it in QT, the grids don't change when I click BACK. I've tried different things for the last three hours, to no avail. Any ideas? gridwindow.cpp - My problem should be in here somewhere. Probably the handleBack() func. #include <iostream> #include "gridwindow.h" using namespace std; // Constructor for window. It constructs the three portions of the GUI and lays them out vertically. GridWindow::GridWindow(QWidget *parent,int rows,int cols) : QWidget(parent) { QHBoxLayout *header = setupHeader(); // Setup the title at the top. QGridLayout *grid = setupGrid(rows,cols); // Setup the grid of colored cells in the middle. QHBoxLayout *buttonRow = setupButtonRow(); // Setup the row of buttons across the bottom. QVBoxLayout *layout = new QVBoxLayout(); // Puts everything together. layout->addLayout(header); layout->addLayout(grid); layout->addLayout(buttonRow); setLayout(layout); } // Destructor. GridWindow::~GridWindow() { delete title; } // Builds header section of the GUI. QHBoxLayout* GridWindow::setupHeader() { QHBoxLayout *header = new QHBoxLayout(); // Creates horizontal box. header->setAlignment(Qt::AlignHCenter); this->title = new QLabel("CONWAY'S GAME OF LIFE",this); // Creates big, bold, centered label (title): "Conway's Game of Life." this->title->setAlignment(Qt::AlignHCenter); this->title->setFont(QFont("Arial", 32, QFont::Bold)); header->addWidget(this->title); // Adds widget to layout. return header; // Returns header to grid window. } // Builds the grid of cells. This method populates the grid's 2D array of GridCells with MxN cells. QGridLayout* GridWindow::setupGrid(int rows,int cols) { isRunning = false; QGridLayout *grid = new QGridLayout(); // Creates grid layout. grid->setHorizontalSpacing(0); // No empty spaces. Cells should be contiguous. grid->setVerticalSpacing(0); grid->setSpacing(0); grid->setAlignment(Qt::AlignHCenter); for(int i=0; i < rows; i++) //Each row is a vector of grid cells. { std::vector<GridCell*> row; // Creates new vector for current row. cells.push_back(row); for(int j=0; j < cols; j++) { GridCell *cell = new GridCell(); // Creates and adds new cell to row. cells.at(i).push_back(cell); grid->addWidget(cell,i,j); // Adds to cell to grid layout. Column expands vertically. grid->setColumnStretch(j,1); } grid->setRowStretch(i,1); // Sets row expansion horizontally. } return grid; // Returns grid. } // Builds footer section of the GUI. QHBoxLayout* GridWindow::setupButtonRow() { QHBoxLayout *buttonRow = new QHBoxLayout(); // Creates horizontal box for buttons. buttonRow->setAlignment(Qt::AlignHCenter); // Clear Button - Clears cell; sets them all to DEAD/white. QPushButton *clearButton = new QPushButton("CLEAR"); clearButton->setFixedSize(100,25); connect(clearButton, SIGNAL(clicked()), this, SLOT(handlePause())); // Pauses timer before clearing. connect(clearButton, SIGNAL(clicked()), this, SLOT(handleClear())); // Connects to clear function to make all cells DEAD/white. buttonRow->addWidget(clearButton); // Forward Button - Steps one step forward. QPushButton *forwardButton = new QPushButton("FORWARD"); forwardButton->setFixedSize(100,25); connect(forwardButton, SIGNAL(clicked()), this, SLOT(handleForward())); // Signals to handleForward function.. buttonRow->addWidget(forwardButton); // Back Button - Steps one step backward. QPushButton *backButton = new QPushButton("BACK"); backButton->setFixedSize(100,25); connect(backButton, SIGNAL(clicked()), this, SLOT(handleBack())); // Signals to handleBack funciton. buttonRow->addWidget(backButton); // Start Button - Starts game when user clicks. Or, resumes game after being paused. QPushButton *startButton = new QPushButton("START/RESUME"); startButton->setFixedSize(100,25); connect(startButton, SIGNAL(clicked()), this, SLOT(handlePause())); // Deletes current timer if there is one. Then restarts everything. connect(startButton, SIGNAL(clicked()), this, SLOT(handleStart())); // Signals to handleStart function. buttonRow->addWidget(startButton); // Pause Button - Pauses simulation of game. QPushButton *pauseButton = new QPushButton("PAUSE"); pauseButton->setFixedSize(100,25); connect(pauseButton, SIGNAL(clicked()), this, SLOT(handlePause())); // Signals to pause function which pauses timer. buttonRow->addWidget(pauseButton); // Quit Button - Exits program. QPushButton *quitButton = new QPushButton("EXIT"); quitButton->setFixedSize(100,25); connect(quitButton, SIGNAL(clicked()), qApp, SLOT(quit())); // Signals the quit slot which ends the program. buttonRow->addWidget(quitButton); return buttonRow; // Returns bottom of layout. } /* SLOT method for handling clicks on the "clear" button. Receives "clicked" signals on the "Clear" button and sets all cells to DEAD. */ void GridWindow::handleClear() { for(unsigned int row=0; row < cells.size(); row++) // Loops through current rows' cells. { for(unsigned int col=0; col < cells[row].size(); col++) // Loops through the rows'columns' cells. { GridCell *cell = cells[row][col]; // Grab the current cell & set its value to dead. cell->setType(DEAD); } } } /* SLOT method for handling clicks on the "start" button. Receives "clicked" signals on the "start" button and begins game simulation. */ void GridWindow::handleStart() { isRunning = true; // It is running. Sets isRunning to true. this->timer = new QTimer(this); // Creates new timer. connect(this->timer, SIGNAL(timeout()), this, SLOT(timerFired())); // Connect "timerFired" method class to the "timeout" signal fired by the timer. this->timer->start(500); // Timer to fire every 500 milliseconds. } /* SLOT method for handling clicks on the "pause" button. Receives "clicked" signals on the "pause" button and stops the game simulation. */ void GridWindow::handlePause() { if(isRunning) // If it is running... this->timer->stop(); // Stops the timer. isRunning = false; // Set to false. } void GridWindow::handleForward() { if(isRunning); // If it's running, do nothing. else timerFired(); // It not running, step forward one step. } void GridWindow::handleBack() { std::vector<std::vector<GridCell*> > cells2; if(isRunning); // If it's running, do nothing. else if(backStack.empty()) cout << "EMPTYYY" << endl; else { cells2 = backStack.peek(); for (unsigned int f = 0; f < cells.size(); f++) // Loop through cells' rows. { for (unsigned int g = 0; g < cells.at(f).size(); g++) // Loop through cells columns. { cells[f][g]->setType(cells2[f][g]->getType()); // Set cells[f][g]'s type to cells2[f][g]'s type. } } cout << "PRE=POP" << endl; backStack.pop(); cout << "OYYYY" << endl; } } // Accessor method - Gets the 2D vector of grid cells. std::vector<std::vector<GridCell*> >& GridWindow::getCells() { return this->cells; } /* TimerFired function: 1) 2D-Vector cells2 is declared. 2) cells2 is initliazed with loops/push_backs so that all its cells are DEAD. 3) We loop through cells, and count the number of LIVE neighbors next to a given cell. --> Depending on how many cells are living, we choose if the cell should be LIVE or DEAD in the next simulation, according to the rules. -----> We save the cell type in cell2 at the same indice (the same row and column cell in cells2). 4) After check all the cells (and save the next round values in cells 2), we set cells's gridcells equal to cells2 gridcells. --> This causes the cells to be redrawn with cells2 types (white or black). */ void GridWindow::timerFired() { backStack.push(cells); std::vector<std::vector<GridCell*> > cells2; // Holds new values for 2D vector. These are the next simulation round of cell types. for(unsigned int i = 0; i < cells.size(); i++) // Loop through the rows of cells2. (Same size as cells' rows.) { vector<GridCell*> row; // Creates Gridcell* vector to push_back into cells2. cells2.push_back(row); // Pushes back row vectors into cells2. for(unsigned int j = 0; j < cells[i].size(); j++) // Loop through the columns (the cells in each row). { GridCell *cell = new GridCell(); // Creates new GridCell. cell->setType(DEAD); // Sets cell type to DEAD/white. cells2.at(i).push_back(cell); // Pushes back the DEAD cell into cells2. } // This makes a gridwindow the same size as cells with all DEAD cells. } for (unsigned int m = 0; m < cells.size(); m++) // Loop through cells' rows. { for (unsigned int n = 0; n < cells.at(m).size(); n++) // Loop through cells' columns. { unsigned int neighbors = 0; // Counter for number of LIVE neighbors for a given cell. // We know check all different variations of cells[i][j] to count the number of living neighbors for each cell. // We check m > 0 and/or n > 0 to make sure we don't access negative indexes (ex: cells[-1][0].) // We check m < size to make sure we don't try to access rows out of the vector (ex: row 5, if only 4 rows). // We check n < row size to make sure we don't access column item out of the vector (ex: 10th item in a column of only 9 items). // If we find that the Type = 1 (it is LIVE), then we add 1 to the neighbor. // Else - we add nothing to the neighbor counter. // Neighbor is the number of LIVE cells next to the current cell. if(m > 0 && n > 0) { if (cells[m-1][n-1]->getType() == 1) neighbors += 1; } if(m > 0) { if (cells[m-1][n]->getType() == 1) neighbors += 1; if(n < (cells.at(m).size() - 1)) { if (cells[m-1][n+1]->getType() == 1) neighbors += 1; } } if(n > 0) { if (cells[m][n-1]->getType() == 1) neighbors += 1; if(m < (cells.size() - 1)) { if (cells[m+1][n-1]->getType() == 1) neighbors += 1; } } if(n < (cells.at(m).size() - 1)) { if (cells[m][n+1]->getType() == 1) neighbors += 1; } if(m < (cells.size() - 1)) { if (cells[m+1][n]->getType() == 1) neighbors += 1; } if(m < (cells.size() - 1) && n < (cells.at(m).size() - 1)) { if (cells[m+1][n+1]->getType() == 1) neighbors += 1; } // Done checking number of neighbors for cells[m][n] // Now we change cells2 if it should switch in the next simulation step. // cells2 holds the values of what cells should be on the next iteration of the game. // We can't change cells right now, or it would through off our other cell values. // Apply game rules to cells: Create new, updated grid with the roundtwo vector. // Note - LIVE is 1; DEAD is 0. if (cells[m][n]->getType() == 1 && neighbors < 2) // If cell is LIVE and has less than 2 LIVE neighbors -> Set to DEAD. cells2[m][n]->setType(DEAD); else if (cells[m][n]->getType() == 1 && neighbors > 3) // If cell is LIVE and has more than 3 LIVE neighbors -> Set to DEAD. cells2[m][n]->setType(DEAD); else if (cells[m][n]->getType() == 1 && (neighbors == 2 || neighbors == 3)) // If cell is LIVE and has 2 or 3 LIVE neighbors -> Set to LIVE. cells2[m][n]->setType(LIVE); else if (cells[m][n]->getType() == 0 && neighbors == 3) // If cell is DEAD and has 3 LIVE neighbors -> Set to LIVE. cells2[m][n]->setType(LIVE); } } // Now we've gone through all of cells, and saved the new values in cells2. // Now we loop through cells and set all the cells' types to those of cells2. for (unsigned int f = 0; f < cells.size(); f++) // Loop through cells' rows. { for (unsigned int g = 0; g < cells.at(f).size(); g++) // Loop through cells columns. { cells[f][g]->setType(cells2[f][g]->getType()); // Set cells[f][g]'s type to cells2[f][g]'s type. } } } stack.h - Here's my stack. #ifndef STACK_H_ #define STACK_H_ #include <iostream> #include "node.h" template <typename T> class Stack { private: Node<T>* top; int listSize; public: Stack(); int size() const; bool empty() const; void push(const T& value); void pop(); T& peek() const; }; template <typename T> Stack<T>::Stack() : top(NULL) { listSize = 0; } template <typename T> int Stack<T>::size() const { return listSize; } template <typename T> bool Stack<T>::empty() const { if(listSize == 0) return true; else return false; } template <typename T> void Stack<T>::push(const T& value) { Node<T>* newOne = new Node<T>(value); newOne->next = top; top = newOne; listSize++; } template <typename T> void Stack<T>::pop() { Node<T>* oldT = top; top = top->next; delete oldT; listSize--; } template <typename T> T& Stack<T>::peek() const { return top->data; // Returns data in top item. } #endif gridcell.cpp - Gridcell implementation #include <iostream> #include "gridcell.h" using namespace std; // Constructor: Creates a grid cell. GridCell::GridCell(QWidget *parent) : QFrame(parent) { this->type = DEAD; // Default: Cell is DEAD (white). setFrameStyle(QFrame::Box); // Set the frame style. This is what gives each box its black border. this->button = new QPushButton(this); //Creates button that fills entirety of each grid cell. this->button->setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); // Expands button to fill space. this->button->setMinimumSize(19,19); //width,height // Min height and width of button. QHBoxLayout *layout = new QHBoxLayout(); //Creates a simple layout to hold our button and add the button to it. layout->addWidget(this->button); setLayout(layout); layout->setStretchFactor(this->button,1); // Lets the buttons expand all the way to the edges of the current frame with no space leftover layout->setContentsMargins(0,0,0,0); layout->setSpacing(0); connect(this->button,SIGNAL(clicked()),this,SLOT(handleClick())); // Connects clicked signal with handleClick slot. redrawCell(); // Calls function to redraw (set new type for) the cell. } // Basic destructor. GridCell::~GridCell() { delete this->button; } // Accessor for the cell type. CellType GridCell::getType() const { return(this->type); } // Mutator for the cell type. Also has the side effect of causing the cell to be redrawn on the GUI. void GridCell::setType(CellType type) { this->type = type; redrawCell(); // Sets type and redraws cell. } // Handler slot for button clicks. This method is called whenever the user clicks on this cell in the grid. void GridCell::handleClick() { // When clicked on... if(this->type == DEAD) // If type is DEAD (white), change to LIVE (black). type = LIVE; else type = DEAD; // If type is LIVE (black), change to DEAD (white). setType(type); // Sets new type (color). setType Calls redrawCell() to recolor. } // Method to check cell type and return the color of that type. Qt::GlobalColor GridCell::getColorForCellType() { switch(this->type) { default: case DEAD: return Qt::white; case LIVE: return Qt::black; } } // Helper method. Forces current cell to be redrawn on the GUI. Called whenever the setType method is invoked. void GridCell::redrawCell() { Qt::GlobalColor gc = getColorForCellType(); //Find out what color this cell should be. this->button->setPalette(QPalette(gc,gc)); //Force the button in the cell to be the proper color. this->button->setAutoFillBackground(true); this->button->setFlat(true); //Force QT to NOT draw the borders on the button } Thanks a lot. Let me know if you need anything else.

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• Le pluriel dans les traductions avec Qt, un article de Jan-Arve Sæther traduit par Jonathan Courtois

  Bonjour, Dans la continuité des traductions des Qt Quarterly, je vous propose aujourd'hui un article expliquant comment gérer au mieux les formes du pluriel des différentes langues dans vos traductions. Les formes du pluriel dans les traductions Aviez-vous déjà connaissance de ces subtilités ? Cet article va-t-il améliorer la qualité des traductions de vos applications ?...

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• Why is Conway's "Game of Life" used for code retreats?

  - by blunders

  Code Retreat is an all-day training event that focuses on the fundamentals of software development. There's a "global" code retreat day coming up, and I'm looking forward to it. That said, I've been to one before and have to say there was a huge amount of chaos... which is fine. One thing that I still don't get is why the "Game of Life" is a good problem for TDD, and what good and bad TDD for it feels like. Realize this is a pretty open ended question, so feel free to comment.

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• How to optimize Conway's game of life for CUDA?

  - by nlight

  I've written this CUDA kernel for Conway's game of life: global void gameOfLife(float* returnBuffer, int width, int height) { unsigned int x = blockIdx.x*blockDim.x + threadIdx.x; unsigned int y = blockIdx.y*blockDim.y + threadIdx.y; float p = tex2D(inputTex, x, y); float neighbors = 0; neighbors += tex2D(inputTex, x+1, y); neighbors += tex2D(inputTex, x-1, y); neighbors += tex2D(inputTex, x, y+1); neighbors += tex2D(inputTex, x, y-1); neighbors += tex2D(inputTex, x+1, y+1); neighbors += tex2D(inputTex, x-1, y-1); neighbors += tex2D(inputTex, x-1, y+1); neighbors += tex2D(inputTex, x+1, y-1); __syncthreads(); float final = 0; if(neighbors < 2) final = 0; else if(neighbors 3) final = 0; else if(p != 0) final = 1; else if(neighbors == 3) final = 1; __syncthreads(); returnBuffer[x + y*width] = final; } I am looking for errors/optimizations. Parallel programming is quite new to me and I am not sure if I get how to do it right. The rest of the app is: Memcpy input array to a 2d texture inputTex stored in a CUDA array. Output is memcpy-ed from global memory to host and then dealt with. As you can see a thread deals with a single pixel. I am unsure if that is the fastest way as some sources suggest doing a row or more per thread. If I understand correctly NVidia themselves say that the more threads, the better. I would love advice on this on someone with practical experience.

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• PCSX2 1.0.0 installation issues

  - by user205261

  I've followed all the tutorials I can find to get this emulator to work and I'm now getting this error. Granted I've gotten a lot further than when I started. Running 13.10. Just downloaded the Linux download file from the pcsx2 website and did the following in terminal: jonathan@Assassin:~$ sudo add-apt-repository ppa:gregory-hainaut/pcsx2.official.ppa [sudo] password for jonathan: The Official pcsx2 ppa, provided by the pcsx2 team. This ppa contains a regular package snapshot of pcsx2. We are not package experts, but we try to follow the debian policy. Press [ENTER] to continue or ctrl-c to cancel adding it gpg: keyring `/tmp/tmpe5fwdz/secring.gpg' created gpg: keyring `/tmp/tmpe5fwdz/pubring.gpg' created gpg: requesting key 7A617FF4 from hkp server keyserver.ubuntu.com gpg: /tmp/tmpe5fwdz/trustdb.gpg: trustdb created gpg: key 7A617FF4: public key "Launchpad official ppa for pcsx2 team" imported gpg: Total number processed: 1 gpg: imported: 1 (RSA: 1) OK jonathan@Assassin:~$ sudo apt-get update Err http://ppa.launchpad.net saucy/main amd64 Packages 404 Not Found Err http://ppa.launchpad.net saucy/main i386 Packages 404 Not Found Fetched 67.4 kB in 16s (3,977 B/s) W: Failed to fetch ppa.launchpad.net/gregory-hainaut/pcsx2.official.ppa/ubuntu/dists/saucy/main/binary-amd64/Packages 404 Not Found W: Failed to fetch ppa.launchpad.net/gregory-hainaut/pcsx2.official.ppa/ubuntu/dists/saucy/main/binary-i386/Packages 404 Not Found E: Some index files failed to download. They have been ignored, or old ones used instead. jonathan@Assassin:~$ sudo apt-get install pcsx2 Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package pcsx2 So I'm assuming I just need the way to get the two missing packages?

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• Apple Script error: Can't get Folder

  - by Jonathan Hirsch

  I started using apple script today, because I wanted to be able to automatically send files to someone when they go into a specific folder. I first tried with automator, but the files were never attached into emails, so i figured i could try with apple script. At first, I tried simply create an email with an attached file. The email was created, but the file was not attached. After a while, I stumbled onto this post that was trying to list files from a folder, so I tried that just to compare it to my code. It gave me an error telling me it is impossible to list files from that folder. So I tried setting a path to a specific folder, and I got an error saying the path can't be made. This is the code I used for the last part: tell application "Finder" set folderPath to folder "Macintosh HD: Users:Jonathan:Desktop:Send_Mail" set fileList to name of every file in folderPath end tell and this is the error I got. error "Finder got an error: Can’t get folder \"Macintosh HD: Users:Jonathan:Desktop:Send_Mail\"." number -1728 from folder "Macintosh HD: Users:Jonathan:Desktop:Send_Mail". I later tried with another folder, and I always get this error, even when using the Users folder for example. Any Suggestions? thanks

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• How can I install Satchmo?

  - by Jonathan Hayward

  I am trying to install Satchmo 0.9 on an Ubuntu 9.10 guest off of the instructions at http://bitbucket.org/chris1610/satchmo/downloads/Satchmo.pdf. I run into difficulties at 2.1.2: pip install -r http://bitbucket.org/chris1610/satchmo/raw/tip/scripts/requirements.txt pip install -e hg+http://bitbucket.org/chris1610/satchmo/@v0.9#egg=satchmo The first command fails because a compile error for how it's trying to build PIL. So I ran an "aptitude install python-imaging", locally copy the first line's requirements.text, and remove the line that's unsuccessfully trying to build PIL. The first line completes without error, as does the second. The next step tells me to change directory to the /path/to/new/store, and run: python clonesatchmo.py A little bit of trouble here; I am told that clonesatchmo.py will be in /bin by now, and it isn't there, but I put some Satchmo stuff under /usr/local, create a symlink in /bin, and run: python /bin/clonesatchmo.py This gives: jonathan@ubuntu:~/store$ python /bin/clonesatchmo.py Creating the Satchmo Application Traceback (most recent call last): File "/bin/clonesatchmo.py", line 108, in <module> create_satchmo_site(opts.site_name) File "/bin/clonesatchmo.py", line 47, in create_satchmo_site import satchmo_skeleton ImportError: No module named satchmo_skeleton A find after apparently checking out the repository reveals that there is no file with a name like satchmo*skeleton* on my system. I thought that bash might be prone to take part of the second pip invocation's URL as the beginning of a comment; I tried both: pip install -e hg+http://bitbucket.org/chris1610/satchmo/@v0.9\#egg=satchmo pip install -e hg+http://bitbucket.org/chris1610/satchmo/@v0.9#egg=satchmo Neither way of doing it seems to take care of the import error mentioned above. How can I get a Satchmo installation under Ubuntu, or at least enough of a Satchmo installation that I am able to start with a skeleton of a store and then flesh it out the way I want? Thanks, Jonathan

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• How can I install Satchmo?

  - by Jonathan Hayward

  I am trying to install Satchmo 0.9 on an Ubuntu 9.10 32-bit guest off of the instructions at http://bitbucket.org/chris1610/satchmo/downloads/Satchmo.pdf. I run into difficulties at 2.1.2: pip install -r http://bitbucket.org/chris1610/satchmo/raw/tip/scripts/requirements.txt pip install -e hg+http://bitbucket.org/chris1610/satchmo/@v0.9#egg=satchmo The first command fails because a compile error for how it's trying to build PIL. So I ran an "aptitude install python-imaging", locally copy the first line's requirements.text, and remove the line that's unsuccessfully trying to build PIL. The first line completes without reported error, as does the second. The next step tells me to change directory to the /path/to/new/store, and run: python clonesatchmo.py A little bit of trouble here; I am told that clonesatchmo.py will be in /bin by now, and it isn't there, but I put some Satchmo stuff under /usr/local, create a symlink in /bin, and run: python /bin/clonesatchmo.py This gives: jonathan@ubuntu:~/store$ python /bin/clonesatchmo.py Creating the Satchmo Application Traceback (most recent call last): File "/bin/clonesatchmo.py", line 108, in <module> create_satchmo_site(opts.site_name) File "/bin/clonesatchmo.py", line 47, in create_satchmo_site import satchmo_skeleton ImportError: No module named satchmo_skeleton A find after apparently checking out the repository reveals that there is no file with a name like satchmo*skeleton* on my system. I thought that bash might be prone to take part of the second pip invocation's URL as the beginning of a comment; I tried both: pip install -e hg+http://bitbucket.org/chris1610/satchmo/@v0.9\#egg=satchmo pip install -e hg+http://bitbucket.org/chris1610/satchmo/@v0.9#egg=satchmo Neither way of doing it seems to take care of the import error mentioned above. How can I get a Satchmo installation under Ubuntu, or at least enough of a Satchmo installation that I am able to start with a skeleton of a store and then flesh it out the way I want? Thanks, Jonathan

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• C# System.IO.Filestream doesn't support Hebrew

  - by Jonathan Dyle

  Hi all Am I missing something or does System.IO.Filestream not read unicode txt files containing Hebrew? Thanks Jonathan

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• .NET 4 Web Application Startup Time

  - by Latest Microsoft Blogs

  I was chatting with Jonathan Hawkins and some of the folks on the ASP.NET team about performance and Jonathan mentioned the startup time for large ASP.NET applications is improved on .NET 4. There are some improvements in the CLR and in ASP.NET itself Read More......(read more)

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• Free eBook "Troubleshooting SQL Server: A Guide for the Accidental DBA"

  - by TATWORTH

  "SQL Server-related performance problems come up regularly and diagnosing and solving them can be difficult and time consuming. Read SQL Server MVP Jonathan Kehayias’ Troubleshooting SQL Server: A Guide for the Accidental DBA for descriptions of the most common issues and practical solutions to fix them quickly and accurately." Please go to http://www.red-gate.com/products/dba/sql-monitor/entrypage/tame-unruly-sql-servers-ebook RedGate produce some superb tools for SQL Server. Jonathan's book is excellent - I commend it to all SQL DBA and developers.

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• System locking up with suspicious messages about hard disk

  - by Chris Conway

  My system has started behaving strangely, intermittently locking up. I see messages like the following in syslog: Nov 18 22:22:00 claypool kernel: [ 3428.078156] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0 Nov 18 22:22:00 claypool kernel: [ 3428.078163] ata3.00: irq_stat 0x40000000 Nov 18 22:22:00 claypool kernel: [ 3428.078167] sr 2:0:0:0: CDB: Test Unit Ready: 00 00 00 00 00 00 Nov 18 22:22:00 claypool kernel: [ 3428.078182] ata3.00: cmd a0/00:00:00:00:00/00:00:00:00:00/a0 tag 0 Nov 18 22:22:00 claypool kernel: [ 3428.078184] res 50/00:03:00:00:00/00:00:00:00:00/a0 Emask 0x1 (device error) Nov 18 22:22:00 claypool kernel: [ 3428.078188] ata3.00: status: { DRDY } Nov 18 22:22:00 claypool kernel: [ 3428.080887] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0 Nov 18 22:22:00 claypool kernel: [ 3428.080890] ata3.00: irq_stat 0x40000000 Nov 18 22:22:00 claypool kernel: [ 3428.080893] sr 2:0:0:0: CDB: Test Unit Ready: 00 00 00 00 00 00 Nov 18 22:22:00 claypool kernel: [ 3428.080905] ata3.00: cmd a0/00:00:00:00:00/00:00:00:00:00/a0 tag 0 Nov 18 22:22:00 claypool kernel: [ 3428.080906] res 50/00:03:00:00:00/00:00:00:00:00/a0 Emask 0x1 (device error) Nov 18 22:22:00 claypool kernel: [ 3428.080910] ata3.00: status: { DRDY } And then this: Nov 18 23:13:56 claypool kernel: [ 6544.000798] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen Nov 18 23:13:56 claypool kernel: [ 6544.000804] ata1.00: failed command: FLUSH CACHE EXT Nov 18 23:13:56 claypool kernel: [ 6544.000814] ata1.00: cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0 Nov 18 23:13:56 claypool kernel: [ 6544.000815] res 40/00:00:00:4f:c2/00:00:00:00:00/40 Emask 0x4 (timeout) Nov 18 23:13:56 claypool kernel: [ 6544.000819] ata1.00: status: { DRDY } Nov 18 23:13:56 claypool kernel: [ 6544.000825] ata1: hard resetting link Nov 18 23:14:01 claypool kernel: [ 6549.360324] ata1: link is slow to respond, please be patient (ready=0) Nov 18 23:14:06 claypool kernel: [ 6554.008091] ata1: COMRESET failed (errno=-16) Nov 18 23:14:06 claypool kernel: [ 6554.008103] ata1: hard resetting link Nov 18 23:14:11 claypool kernel: [ 6559.372246] ata1: link is slow to respond, please be patient (ready=0) Nov 18 23:14:16 claypool kernel: [ 6564.020228] ata1: COMRESET failed (errno=-16) Nov 18 23:14:16 claypool kernel: [ 6564.020235] ata1: hard resetting link Nov 18 23:14:21 claypool kernel: [ 6569.380109] ata1: link is slow to respond, please be patient (ready=0) Nov 18 23:14:31 claypool kernel: [ 6579.460243] ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Nov 18 23:14:31 claypool kernel: [ 6579.486595] ata1.00: configured for UDMA/133 Nov 18 23:14:31 claypool kernel: [ 6579.486601] ata1.00: retrying FLUSH 0xea Emask 0x4 Nov 18 23:14:31 claypool kernel: [ 6579.486939] ata1.00: device reported invalid CHS sector 0 Nov 18 23:14:31 claypool kernel: [ 6579.486952] ata1: EH complete Nov 18 23:17:01 claypool CRON[3910]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Nov 18 23:17:01 claypool CRON[3908]: (CRON) error (grandchild #3910 failed with exit status 1) Nov 18 23:17:01 claypool postfix/sendmail[3925]: fatal: open /etc/postfix/main.cf: No such file or directory Nov 18 23:17:01 claypool CRON[3908]: (root) MAIL (mailed 1 byte of output; but got status 0x004b, #012) Nov 18 23:39:01 claypool CRON[4200]: (root) CMD ( [ -x /usr/lib/php5/maxlifetime ] && [ -d /var/lib/php5 ] && find /var/lib/php5/ -type f -cmin +$(/usr/lib/php5/maxlifetime) -print0 | xargs -n 200 -r -0 rm) There are no messages marked after 23:39. When I next tried to use the machine, it would not return from the screensaver (blank screen), nor switch to another terminal, and I had to hard reboot it. [UPDATE] The output of smartctl is here. I had trouble getting this, because / is being mounted read-only (?!), which prevents most applications from running. Also, it may not be related, but I have the following worrying messages in dmesg: [ 10.084596] k8temp 0000:00:18.3: Temperature readouts might be wrong - check erratum #141 [ 10.098477] i2c i2c-0: nForce2 SMBus adapter at 0x600 [ 10.098483] ACPI: resource nForce2_smbus [io 0x0700-0x073f] conflicts with ACPI region SM00 [??? 0x00000700-0x0000073f flags 0x30] [ 10.098486] ACPI: This conflict may cause random problems and system instability [ 10.098487] ACPI: If an ACPI driver is available for this device, you should use it instead of the native driver [ 10.098509] i2c i2c-1: nForce2 SMBus adapter at 0x700 [ 10.112570] Linux agpgart interface v0.103 [ 10.155329] atk: Resources not safely usable due to acpi_enforce_resources kernel parameter [ 10.161506] it87: Found IT8712F chip at 0x290, revision 8 [ 10.161517] it87: VID is disabled (pins used for GPIO) [ 10.161527] it87: in3 is VCC (+5V) [ 10.161528] it87: in7 is VCCH (+5V Stand-By) [ 10.161560] ACPI: resource it87 [io 0x0295-0x0296] conflicts with ACPI region ECRE [??? 0x00000290-0x000002af flags 0x45] [ 10.161562] ACPI: This conflict may cause random problems and system instability [ 10.161564] ACPI: If an ACPI driver is available for this device, you should use it instead of the native driver [UPDATE 2] I swapped in a new SATA cable, per Phil's suggestion. The current output of smartctl is here, if it helps. [UPDATE 3] I don't think the cable fixed it. The system hasn't locked up yet, but my media player crashed a few minutes ago and I have the following in the syslog: Nov 20 16:07:17 claypool kernel: [ 2294.400033] ata1: link is slow to respond, please be patient (ready=0) Nov 20 16:07:47 claypool kernel: [ 2324.084581] ata1: COMRESET failed (errno=-16) Nov 20 16:07:47 claypool kernel: [ 2324.084588] ata1: limiting SATA link speed to 1.5 Gbps Nov 20 16:07:47 claypool kernel: [ 2324.084592] ata1: hard resetting link I get the following response from smartctl: $ sudo smartctl -a /dev/sda [sudo] password for chris: sudo: Can't open /var/lib/sudo/chris/0: Read-only file system smartctl 5.40 2010-03-16 r3077 [i686-pc-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net Device: /0:0:0:0 Version: scsiModePageOffset: response length too short, resp_len=47 offset=50 bd_len=46 >> Terminate command early due to bad response to IEC mode page A mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options.

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• What do DBAs do?

  - by Jonathan Conway

  Yes, I know they administrate databases. I asked this question because I'd like to get a further insight into the kind of day-to-day duties a DBA might perform, and the real-world business problems they solve. For example: I optimized a 'products' query so that it ran 25% faster, which made the overall application faster. Is this a typical duty? Or is there more to being a DBA than simply making things faster? In what situations does DBA work involve planning and creativity?

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• Brand new battery is 100% charged but at 0% capacity

  - by Chris Conway

  I just bought a brand new battery to replace one that had seemingly died. I followed the instructions that came with the battery and charged it overnight, then ran my computer on battery until it was in a critical state and charged it overnight again. Now the battery appears to be 100% charged and at the same time at 0% capacity—when it's plugged in it doesn't charge and when it's unplugged the computer immediately goes into low power mode. I've taken the battery out and checked the contacts. I've rebooted the system with and without the battery. Nothing seems to help. I'm not sure if I should blame the battery, the laptop, the charger, or the power management software for this state of affairs. The obvious answer would be the battery but I bought this battery because another year-old battery exhibited similar behavior—I assumed it was dead and a Dell tech came to the same conclusion. I'm loathe to order another new battery without first exploring other explanations. What can I do to diagnose this problem? Here's the /proc info: $ cat /proc/acpi/battery/BAT0/state present: yes capacity state: critical charging state: charged present rate: 1 mA remaining capacity: 0 mAh present voltage: 9754 mV $ cat /proc/acpi/battery/BAT0/info present: yes design capacity: 6600 mAh last full capacity: 6789 mAh battery technology: rechargeable design voltage: 11100 mV design capacity warning: 660 mAh design capacity low: 200 mAh cycle count: 0 capacity granularity 1: 66 mAh capacity granularity 2: 66 mAh model number: DELL WK serial number: 4043 battery type: LION OEM info: SMP

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• Leading an offshore team

  - by Chuck Conway

  I'm in a position where I am leading two teams of 4. Both teams are located in India. I am on the west coast of the U.S. I'm finding leading remote teams challenging: First, their command of the English language is weak. Second, I'm having difficultly understanding them through their accents. Third is timing, we are 12 hours apart. We use Skype to communicate. I have a month to get the project done. We've burned through a week just setting up the environments. At this point I'm considering working their hours, 11p PDT to 7a PDT, to get them up to speed, so that I can get the project off the ground. A 12 hour lag time is too much. I'm looking for steps I can take to be successful at leading an offshore team. Update The offshore team's primary task is coding, of course, most coding tasks do involve some design work. The offshore team's are composed of one lead, 2 mid level (4 to 5 years) developers and a junior (~2 years) developer. The project is classic waterfall. We've handed the offshore team a business and a technical design document. We are trying to manage the offshore in an agile way. We have daily conference calls with them and I'm requiring the teams to send me a daily scrum in the form of an email answering the following questions: What did I do today? What am I going to do tomorrow? What do I need from Chuck so I can do my job tomorrow? There is some ambiguity in the tasks. The intent was to give them enough direction for them to develop the task with out writing the code for them. I don't have a travel budget. I am using Fogbugz to track the tasks. Each task has been entered into Fogbugz and given a priority. Each team member has access to FogBugz and can choose what task they wish to complete. Related question: What can we do to improve the way outsourcing/offshoring works? Update 2 I've decided that I can not talk to the team once a day. I must work with them. Starting tonight I've started working the same hours they are. This makes me available to them when they have questions. It also allows me to gain their trust and respect. Stackoverflow question Leading an offshore team

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• BDD/TDD vs JAD?

  - by Jonathan Conway

  I've been proposing that my workplace implement Behavior-Driven-Development, by writing high-level specifications in a scenario format, and in such a way that one could imagine writing a test for it. I do know that working against testable specifications tends to increase developer productivity. And I can already think of several examples where this would be the case on our own project. However it's difficult to demonstrate the value of this to the business. This is because we already have a Joint Application Development (JAD) process in place, in which developers, management, user-experience and testers all get together to agree on a common set of requirements. So, they ask, why should developers work against the test-cases created by testers? These are for verification and are based on the higher-level specs created by the UX team, which the developers currently work off. This, they say, is sufficient for developers and there's no need to change how the specs are written. They seem to have a point. What is the actual benefit of BDD/TDD, if you already have a test-team who's test cases are fully compatible with the higher-level specs currently given to the developers?

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• How do I ban a wifi network in Network Manager?

  - by Chris Conway

  My wifi connection drops sometimes and, for some reason, Network Manager attempts to connect to my neighbor's network, which requires a password that I don't know. The network in question is not listed in the "Edit Connections..." dialog and I can find no reference to it in any configuration file, but still the password dialog pops up every time my main connection drops. Is there a way to blacklist a wireless network so that the Network Manager will never attempt to connect to it? Or, equivalently, how can I remove the configuration data that causes the Network Manager to attempt to connect to this particular network?

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• dazzle DVC100 in live movie maker

  - by Jonathan

  How can I use the Pinnacle Dazzle (it is a USB device which lets you plug in a video player or other analogue source) with Windows live movie maker (because it is just simple and I don't need effects/editing etc) Or is there a way I can use it on my Macbook Pro? Jonathan

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• Is pdf virus proof?

  - by Jonathan

  I am creating a secure document portal for a client. One of the things that they are worried about is having someone upload a document with a virus. One solution that might work is to enforce that they only upload pdf files. My question is two fold: Most importantly, is a pdf document virus proof? How can you determine in a *nix environment that a file is a pdf, besides just looking at the extension. Thanks! Jonathan

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