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  • How often do you review fundamentals?

    - by mlnyc
    So I've been out of school for a year and a half now. In school, of course we covered all the fundamentals: OS, databases, programming languages (i.e. syntax, binding rules, exception handling, recursion, etc), and fundamental algorithms. the rest were more in-depth topics on things like NLP, data mining, etc. Now, a year ago if you would have told me to write a quicksort, or reverse a singly-linked list, analyze the time complexity of this 'naive' algorithm vs it's dynamic programming counterpart, etc I would have been able to give you a decent and hopefully satisfying answer. But if you would have asked me more real world questions I might have been stumped (things like how would handle logging for an application, or security difference between GET and POST, differences between SQL Server and Oracle SQL, anything I list on my resume as currently working with [jQuery questions, ColdFusion questions, ...] etc) Now, I feel things are the opposite. I haven't wrote my own sort since graduating, and I don't really have to worry much about theoretical things that do not naturally fall into problems I am trying to solve. For example, I might give you some great SQL solutions using an analytical function that I would have otherwise been stumped on or write a cool web application using angular or something but ask me to write an algo for insertAfter(Element* elem) and I might not be able to do it in a reasonable time frame. I guess my question here to the experienced programmers is how do you balance the need to both learn and experiment with new technologies (fun!), working on personal projects (also fun!) working and solving real world problems in a timeboxed environment (so I might reach out to a library that does what I want rather than re-invent the wheel so that I can focus on the problem I am trying to solve) (work, basically), and refreshing on old theoretical material which is still valid for interviews and such (can be a drag)? Do you review older material (such as famous algorithms, dynamic programming, Big-O analysis, locking implementations) regularly or just when you need it? How much time do you dedicate to both in your 'deliberate practice' and do you have a certain to-do list of topics that you want to work on?

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  • Solaris 11 VNC Server is "blurry" or "smeared"

    - by user12620111
    I've been annoyed by quality of the image that is displayed by my VNC viewer when I visit a Solaris 11 VNC server. How should I describe the image? Blurry? Grainy? Smeared? Low resolution? Compressed? Badly encoded? This is what I have gotten used to seeing on Solaris 11: This is not a problem for me when I view Solaris 10 VNC servers. I've finally taken the time to investigate, and the solution is simple. On the VNC client, don't allow "Tight" encoding. My VNC Viewer will negotiate to Tight encoding if it is available. When negotiating with the Solaris 10 VNC server, Tight is not a supported option, so the Solaris 10 server and my client will agree on ZRLE.  Now that I have disabled Tight encoding on my VNC client, the Solaris 11 VNC Servers looks much better: How should I describe the display when my VNC client is forced to negotiate to ZRLE encoding with the Solaris 11 VNC Server? Crisp? Clear? Higher resolution? Using a lossless compression algorithm? When I'm on a low bandwidth connection, I may re-enable Tight compression on my laptop. In the mean time, the ZRLE compression is sufficient for a coast-to-coast desktop, through the corporate firewall, encoded with VPN, through my ISP and onto my laptop. YMMV.

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  • Steering evaluate fitness

    - by Vodemki
    I've made a simple game with a steering model that manage a crowd of agents. I use an genetic algorithm to find the best parameters to use in my system but I need to determine a fitness for each simulation. I know it's something like that: number of collisions * time to reach goal * effort But I don't know how to calculate the effort, is there a special way to do that ? Here is what I've done so far: // Evaluate the distance from agents to goal Real totalDistance(0.0); for (unsigned i=0; i<_agents.size(); i++) { totalDistance += _agents[i]->position().distance(_agents[i]->_goal->position()); } Real totalWallsCollision(0.0); for (unsigned i=0; i<_agents.size(); i++) { for (unsigned j=0; j<walls.size(); j++) { if ( walls[j]->inside(_agents[i]->position()) ) { totalCollision += 1.0; } } } return totalDistance + totalWallsCollision; Thanks for your help.

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  • Determining whether two fast moving objects should be submitted for a collision check

    - by dreta
    I have a basic 2D physics engine running. It's pretty much a particle engine, just uses basic shapes like AABBs and circles, so no rotation is possible. I have CCD implemented that can give accurate TOI for two fast moving objects and everything is working smoothly. My issue now is that i can't figure out how to determine whether two fast moving objects should even be checked against each other in the first place. I'm using a quad tree for spacial partitioning and for each fast moving object, i check it against objects in each cell that it passes. This works fine for determining collision with static geometry, but it means that any other fast moving object that could collide with it, but isn't in any of the cells that are checked, is never considered. The only solution to this i can think of is to either have the cells large enough and cross fingers that this is enough, or to implement some sort of a brute force algorithm. Is there a proper way of dealing with this, maybe somebody solved this issue in an efficient manner. Or maybe there's a better way of partitioning space that accounts for this?

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  • What is the best way to manage large 3d worlds (i.e minecraft style)?

    - by SomeXnaChump
    After playing minecraft I was marvelling a bit at their large worlds but at the same time finding it extremely slow to navigate, even with a quad core and meaty graphics card. Now I assume its fairly slow because: A) Its written in Java, and as most of the actual spatial partitioning and other memory management activities happen in there it would be slower than a native C++ version. B) They are not partitioning their world very well I could be wrong on both assumptions, however it got me thinking about the best way to manage large worlds. As it is more of a true 3d world, where a block can exist in any part of the world, it is basically a big 3d array [x][y][z], where each block in the world has a type (i.e BlockType.Empty = 0, BlockType.Dirt = 1 etc). Now I am assuming to make this sort of world performant you would need to: a) Use a tree of some variety (oct/kd/bsp) to split all the cubes out, it seems like an oct/kd would be the better option as you can just partition on a per cube level not a per triangle level. b) Use some algorithm to work out if the blocks within the scene can currently be seen, as blocks closer to the user could obfuscate the blocks behind, making it pointless to render them. c) Keep the block object themselves lightweight, so it is quick to add and remove them from the trees I guess there is no right answer to this, but I would be interested to see peoples opinions on the subject.

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  • Random generation of interesting puzzle levels?

    - by monsterfarm
    I'm making a Sokoban-like game i.e. there's a grid that has some crates on it you can push and you have to get the crates on crosses to win the level (although I'm going to add some extra elements to it). Are there any general algorithms or reading material I can look at for how I could go about generating interesting (as in, not trivial to solve) levels for this style of game? I'm aware that random level generators exist for Sokoban but I'm having trouble finding the algorithm descriptions. I'm interested in making a game where the machine can generate lots of levels for me, sorted by difficulty. I'm even willing to constrain the rules of the game to make the level generation easier (e.g. I'll probably limit the grid size to about 7x7). I suspect there are some general ways to do level generation here as I've seen e.g. Traffic Jam-like games (where you have to move blocks around the free some block) with 1000s of levels where each one has a unique solution. One idea I had was to generate a random map in its final state (i.e. where all crates are on top of their crosses) and then the computer would pull (instead of push) these crates around to create a level. The nice property here is that we know the level is solvable. However, I'd need some heuristics to ensure the level was interesting.

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  • Should Starting a Quick Game via Google Game Services be Iterated?

    - by user46727
    I have been following this tutorial for Google Play Game Services. I am a little unclear as to if the room matching algorithm should be looped or not. Can I just initialize this process once and let it time out? Or by iterating through it is it somehow rechecking it? If anyone had the approximate timeout that would be great as well. The problem stems from the fact that even when both phones are signing into the Game Services (at virtually the same time, my friend and I logged in), the room is not registering multiple people. One time my friend's phone even entered the game map, showing that he somehow was able to progress from the room initialization process. Relevant screen update methods which I am starting this matchmaking process: @Override public void update(float deltaTime) { game.options.updateTiles(); if(!isInitiated) { startQuickGame(); } } private void startQuickGame() { // auto-match criteria to invite one random automatch opponent. // You can also specify more opponents (up to 3). if(game.mGoogleClient.isConnected() && !isInitiated) { Bundle am = RoomConfig.createAutoMatchCriteria(1, 3, 0); // build the room config: RoomConfig.Builder roomConfigBuilder = RoomConfig.builder(Network.getInstance()); roomConfigBuilder.setMessageReceivedListener(Network.getInstance()); roomConfigBuilder.setRoomStatusUpdateListener(Network.getInstance()); roomConfigBuilder.setAutoMatchCriteria(am); RoomConfig roomConfig = roomConfigBuilder.build(); // create room: Games.RealTimeMultiplayer.create(game.mGoogleClient, roomConfig); // go to game screen this.mRoom = Network.getInstance().getRoom(); if(this.mRoom != null && this.mRoom.getParticipants().size() >= 2) { game.setScreen(new MultiGameScreen(game, this.mRoom)); isInitiated = true; } } else { game.mGoogleClient.connect(); } }

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  • Discrete Math and Computing Course

    - by ShrimpCrackers
    I was recently admitted into a Computing and Software Systems program (basically software engineering) and one of the first courses I'll be taking is called Mathematical Principles of Computing. The course description: "Integrating mathematical principles with detailed instruction in computer programming. Explores mathematical reasoning and discrete structures through object-oriented programming. Includes algorithm analysis, basic abstract data types, and data structures." I'm not a fan of math, but I've been doing well in all my math classes mostly A's and B's ever since I started two years ago, and I've been doing math every quarter - never took a quarter without math - so I've been doing it all in sequence without gaps. However, I'm worried about this class. I've read briefly on what discrete math is and from what my advisor told me, its connection with computer science is that it has alot to do with proving algorithms. One thing that my instructors briefly touched on and never went into detail was proving algorithms, and when I tried, I just wasn't very good at mathematical induction. It's one of the things that I ignored every time it showed up in a homework problem (usually in Calculus III which I'm finishing up right now). Questions: 1. What can I expect from this class? 2. How can I prepare myself for this class? 3. Other tips? Thank you.

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  • How to build a "traffic AI"?

    - by Lunikon
    A project I am working on right now features a lot of "traffic" in the sense of cars moving along roads, aircraft moving aroun an apron etc. As of now the available paths are precalculated, so nodes are generated automatically for crossings which themselves are interconnected by edges. When a character/agent spawns into the world it starts at some node and finds a path to a target node by means of a simply A* algorithm. The agent follows the path and ultimately reaches its destination. No problem so far. Now I need to enable the agents to avoid collisions and to handle complex traffic situations. Since I'm new to the field of AI I looked up several papers/articles on steering behavior but found them to be too low-level. My problem consists less of the actual collision avoidance (which is rather simple in this case because the agents follow strictly defined paths) but of situations like one agent leaving a dead-end while another one wants to enter exactly the same one. Or two agents meeting at a bottleneck which only allows one agent to pass at a time but both need to pass it (according to the optimal route found before) and they need to find a way to let the other one pass first. So basically the main aspect of the problem would be predicting traffic movement to avoid dead-locks. Difficult to describe, but I guess you get what I mean. Do you have any recommendations for me on where to start looking? Any papers, sample projects or similar things that could get me started? I appreciate your help!

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  • High-level strategy for distinguishing a regular string from invalid JSON (ie. JSON-like string detection)

    - by Jonline
    Disclaimer On Absence of Code: I have no code to post because I haven't started writing; was looking for more theoretical guidance as I doubt I'll have trouble coding it but am pretty befuddled on what approach(es) would yield best results. I'm not seeking any code, either, though; just direction. Dilemma I'm toying with adding a "magic method"-style feature to a UI I'm building for a client, and it would require intelligently detecting whether or not a string was meant to be JSON as against a simple string. I had considered these general ideas: Look for a sort of arbitrarily-determined acceptable ratio of the frequency of JSON-like syntax (ie. regex to find strings separated by colons; look for colons between curly-braces, etc.) to the number of quote-encapsulated strings + nulls, bools and ints/floats. But the smaller the data set, the more fickle this would get look for key identifiers like opening and closing curly braces... not sure if there even are more easy identifiers, and this doesn't appeal anyway because it's so prescriptive about the kinds of mistakes it could find try incrementally parsing chunks, as those between curly braces, and seeing what proportion of these fractional statements turn out to be valid JSON; this seems like it would suffer less than (1) from smaller datasets, but would probably be much more processing-intensive, and very susceptible to a missing or inverted brace Just curious if the computational folks or algorithm pros out there had any approaches in mind that my semantics-oriented brain might have missed. PS: It occurs to me that natural language processing, about which I am totally ignorant, might be a cool approach; but, if NLP is a good strategy here, it sort of doesn't matter because I have zero experience with it and don't have time to learn & then implement/ this feature isn't worth it to the client.

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  • What is the best way to store a table in C++

    - by Topo
    I'm programming a decision tree in C++ using a slightly modified version of the C4.5 algorithm. Each node represents an attribute or a column of your data set and it has a children per possible value of the attribute. My problem is how to store the training data set having in mind that I have to use a subset for each node so I need a quick way to only select a subset of rows and columns. The main goal is to do it in the most memory and time efficient possible (in that order of priority). The best way I have thought of is to have an array of arrays (or std::vector), or something like that, and for each node have a list (array, vector, etc) or something with the column,line(probably a tuple) pairs that are valid for that node. I now there should be a better way to do this, any suggestions? UPDATE: What I need is something like this: In the beginning I have this data: Paris 4 5.0 True New York 7 1.3 True Tokio 2 9.1 False Paris 9 6.8 True Tokio 0 8.4 False But for the second node I just need this data: Paris 4 5.0 New York 7 1.3 Paris 9 6.8 And for the third node: Tokio 2 9.1 Tokio 0 8.4 But with a table of millions of records with up to hundreds of columns. What I have in mind is keep all the data in a matrix, and then for each node keep the info of the current columns and rows. Something like this: Paris 4 5.0 True New York 7 1.3 True Tokio 2 9.1 False Paris 9 6.8 True Tokio 0 8.4 False Node 2: columns = [0,1,2] rows = [0,1,3] Node 3: columns = [0,1,2] rows = [2,4] This way on the worst case scenario I just have to waste size_of(int) * (number_of_columns + number_of_rows) * node That is a lot less than having an independent data matrix for each node.

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  • Scale an image with unscalable parts

    - by Uko
    Brief description of problem: imagine having some vector picture(s) and text annotations on the sides outside of the picture(s). Now the task is to scale the whole composition while preserving the aspect ratio in order to fit some view-port. The tricky part is that the text is not scalable only the picture(s). The distance between text and the image is still relative to the whole image, but the text size is always a constant. Example: let's assume that our total composition is two times larger than a view-port. Then we can just scale it by 1/2. But because the text parts are a fixed font size, they will become larger than we expect and won't fit in the view-port. One option I can think of is an iterative process where we repeatedly scale our composition until the delta between it and the view-port satisfies some precision. But this algorithm is quite costly as it involves working with the graphics and the image may be composed of a lot of components which will lead to a lot of matrix computations. What's more, this solution seems to be hard to debug, extend, etc. Are there any other approaches to solving this scaling problem?

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  • Are you satisfied with your programming? [closed]

    - by Richart Bremer
    If you are a programmer, are you satisfied with it? I really love to code. I code all kinds of things. I used to play computer games but they are not that interesting compared to developing a new search algorithm or similar. But sometimes I look into the future and see myself being 80 years old, sitting in front of a computer and everything I will have written will be rewritten because the programming languages do not exist anymore. I look back on my life and think "that's it?". Everything I wrote in the past is virtual and ultimately gone. I tried other things but coding is the only thing that does it for me. And at the same time I think I am wasting my life. What about you? Disclaimer: I presume this is the best forum for this question. If you don't agree suggest better place to migrate the question. If you can't, don't close it. Thank you.

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  • Problem with understanding how to start

    - by Coolface
    Okay, this might be a little off-topic but i try anyway. Sorry to bother. So i'm working as sysadmin for at least 5 years now and i quite enjoy IT field in general. Somehow i was never interested in programming much but always want to learn something at least easy and for personal usage. As sysadmin i need scripting skills so learn shell scripting without much problems, i also try to learn pascal, delphi, basic over time and must recent was python. Well, my problem is when i try to learn programming i just can't apply what i learn from the books to the real word. What i mean is i understand there are data structures, algorithms, variables, lib's, if-then logic, etc. but i just can't understand how to apply this things when i want to do real things. Like i want to get a something simple as parse web page, i draw a quick algorithm like get a web page, find a word on it and write a to file, on the paper everything look simple but when i get to the coding i just stuck pretty much from the start. I try read code of the real programs that just totally confusing especially big parts with many classes so i'm just quickly lost a trail what this code do. I think i just lack some fundamentals to see a big picture but don't really know what this might be? Or maybe i just don't have a passion to programming at all... My best bet was a shell scripting so i have really no problems to write complex scripts but this just not enough. Recently i was read around 5 or 6 python books because everyone say it's so easy even kid can code something but still no much luck, python is good and easy but i can't make something harder then a prodecurial style code like in bash for easy things but when i want harder things i'm still stuck. In college i was also not a math and tech guy and like to study non-tech stuff mostly like economy, psychology maybe that my problem? Anyway any advice would be greatly appriciated.

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  • Django + gunicorn + virtualenv + Supervisord issue

    - by Florian Le Goff
    Dear all, I have a strange issue with my virtualenv + gunicorn setup, only when gunicorn is launched via supervisord. I do realize that it may very well be an issue with my supervisord and I would appreciate any feedback on a better place to ask for help... In a nutshell : when I run gunicorn from my user shell, inside my virtualenv, everything is working flawlessly. I'm able to access all the views of my Django project. When gunicorn is launched by supervisord at the system startup, everything is OK. But, if I have to kill the gunicorn_django processes, or if I perform a supervisord restart, once that gunicorn_django has relaunched, every request is answered with a weird Traceback : (...) File "/home/hc/prod/venv/lib/python2.6/site-packages/Django-1.2.5-py2.6.egg/django/db/__init__.py", line 77, in connection = connections[DEFAULT_DB_ALIAS] File "/home/hc/prod/venv/lib/python2.6/site-packages/Django-1.2.5-py2.6.egg/django/db/utils.py", line 92, in __getitem__ backend = load_backend(db['ENGINE']) File "/home/hc/prod/venv/lib/python2.6/site-packages/Django-1.2.5-py2.6.egg/django/db/utils.py", line 50, in load_backend raise ImproperlyConfigured(error_msg) TemplateSyntaxError: Caught ImproperlyConfigured while rendering: 'django.db.backends.postgresql_psycopg2' isn't an available database backend. Try using django.db.backends.XXX, where XXX is one of: 'dummy', 'mysql', 'oracle', 'postgresql', 'postgresql_psycopg2', 'sqlite3' Error was: cannot import name utils Full stack available here : http://pastebin.com/BJ5tNQ2N I'm running... Ubuntu/maverick (up-to-date) Python = 2.6.6 virtualenv = 1.5.1 gunicorn = 0.12.0 Django = 1.2.5 psycopg2 = '2.4-beta2 (dt dec pq3 ext)' gunicorn configuration : backlog = 2048 bind = "127.0.0.1:8000" pidfile = "/tmp/gunicorn-hc.pid" daemon = True debug = True workers = 3 logfile = "/home/hc/prod/log/gunicorn.log" loglevel = "info" supervisord configuration : [program:gunicorn] directory=/home/hc/prod/hc command=/home/hc/prod/venv/bin/gunicorn_django -c /home/hc/prod/hc/gunicorn.conf.py user=hc umask=022 autostart=True autorestart=True redirect_stderr=True Any advice ? I've been stuck on this one for quite a while. It seems like some weird memory limit, as I'm not enforcing anything special : $ ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 20 file size (blocks, -f) unlimited pending signals (-i) 16382 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) unlimited virtual memory (kbytes, -v) unlimited file locks (-x) unlimited Thank you.

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  • gunicorn + django + nginx unix://socket failed (11: Resource temporarily unavailable)

    - by user1068118
    Running very high volume traffic on these servers configured with django, gunicorn, supervisor and nginx. But a lot of times I tend to see 502 errors. So I checked the nginx logs to see what error and this is what is recorded: [error] 2388#0: *208027 connect() to unix:/tmp/gunicorn-ourapp.socket failed (11: Resource temporarily unavailable) while connecting to upstream Can anyone help debug what might be causing this to happen? This is our nginx configuration: sendfile on; tcp_nopush on; tcp_nodelay off; listen 80 default_server; server_name imp.ourapp.com; access_log /mnt/ebs/nginx-log/ourapp-access.log; error_log /mnt/ebs/nginx-log/ourapp-error.log; charset utf-8; keepalive_timeout 60; client_max_body_size 8m; gzip_types text/plain text/xml text/css application/javascript application/x-javascript application/json; location / { proxy_pass http://unix:/tmp/gunicorn-ourapp.socket; proxy_pass_request_headers on; proxy_read_timeout 600s; proxy_connect_timeout 600s; proxy_redirect http://localhost/ http://imp.ourapp.com/; #proxy_set_header Host $host; #proxy_set_header X-Real-IP $remote_addr; #proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; #proxy_set_header X-Forwarded-Proto $my_scheme; #proxy_set_header X-Forwarded-Ssl $my_ssl; } We have configure Django to run in Gunicorn as a generic WSGI application. Supervisord is used to launch the gunicorn workers: home/user/virtenv/bin/python2.7 /home/user/virtenv/bin/gunicorn --config /home/user/shared/etc/gunicorn.conf.py daggr.wsgi:application This is what the gunicorn.conf.py looks like: import multiprocessing bind = 'unix:/tmp/gunicorn-ourapp.socket' workers = multiprocessing.cpu_count() * 3 + 1 timeout = 600 graceful_timeout = 40 Does anyone know where I can start digging to see what might be causing the problem? This is what my ulimit -a output looks like on the server: core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 59481 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 50000 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 1024 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited

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  • Why is my new Phenom II 965 BE not significantly faster than my old Athlon 64 X2 4600+?

    - by Software Monkey
    I recently rebuilt my 5 year old computer. I upgraded all core components, in particular from an Athlon 64 X2 4600+ at 2.4 GHz with DDR2 800 to a Phenom II 965 BE (quad core) at 3.6 GHz with DDR3 1333 (actually 1600, but testing consistently detected memory errors at 1600). The motherboard is also much newer and better. The HDD's (x3), DVD writer and card reader are the same. The BIOS memory config is auto-everything except the base timing which I overrode to 1T instead of 2T. The BIOS CPU multiplier is slightly over-clocked to 3.6 GHz from the stock 3.4 GHz. I noticed compiling Java is slower than I expected. As it happens I have some (single-threaded) Java pattern-matching code which is CPU and memory bound and for which I have performance numbers recorded on a number of hardware platforms, including my old system. So I did a test run on the new equipment and was stunned to find that the numbers are only slightly better than my old system, about 25%. The data set it is operating on is a 148,975 character array, which should easily fit in caches, but in any event the new CPU has larger caches all around. The system was, of course, otherwise idle for the test and the test run is a timed 10 seconds to eliminate scheduling anomalies. A long while ago, when I upgraded only memory from DD2 667 to DDR2 800 there was no change in performance of this test, which subjectively supports that the test cycle does not need to (significantly) access main memory, but yes it is creating and garbage collecting a large number of objects in the process of this test (low millions of matches are found for the pattern set). I am about 99.999% certain the code hasn't changed since I last ran it on 2009-03-17 - but I can't easily retest the old hardware, because it is currently in pieces on my work-bench waiting to be built into a new computer for my kids. Note that Windows (XP) reports a CPU speed of 795 MHz unless I have some thing running. With stuff running it seems to jump all over the place each time I use ALT-Pause to display the system properties, everywhere from 795 MHz to 3.4 Ghz. So why might my shiny new hardware under-performing so badly? EDIT: The old memory was Mushkin DDR2 800 with timings set for auto which should have been 5-5-5-12. The new memory is Corsair DDR3 1600, running at 1333 with timings also auto which are 9-9-9-21. In both cases they are a paired set of dual channel DIMMs. I was waiting to ensure my system was stable before tweaking with memory timings.

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  • Linux per-process resource limits - a deep Red Hat Mystery

    - by BobBanana
    I have my own multithreaded C program which scales in speed smoothly with the number of CPU cores.. I can run it with 1, 2, 3, etc threads and get linear speedup.. up to about 5.5x speed on a 6-core CPU on a Ubuntu Linux box. I had an opportunity to run the program on a very high end Sunfire x4450 with 4 quad-core Xeon processors, running Red Hat Enterprise Linux. I was eagerly anticipating seeing how fast the 16 cores could run my program with 16 threads.. But it runs at the same speed as just TWO threads! Much hair-pulling and debugging later, I see that my program really is creating all the threads, they really are running simultaneously, but the threads themselves are slower than they should be. 2 threads runs about 1.7x faster than 1, but 3, 4, 8, 10, 16 threads all run at just net 1.9x! I can see all the threads are running (not stalled or sleeping), they're just slow. To check that the HARDWARE wasn't at fault, I ran SIXTEEN copies of my program independently, simultaneously. They all ran at full speed. There really are 16 cores and they really do run at full speed and there really is enough RAM (in fact this machine has 64GB, and I only use 1GB per process). So, my question is if there's some OPERATING SYSTEM explanation, perhaps some per-process resource limit which automatically scales back thread scheduling to keep one process from hogging the machine. Clues are: My program does not access the disk or network. It's CPU limited. Its speed scales linearly on a single CPU box in Ubuntu Linux with a hexacore i7 for 1-6 threads. 6 threads is effectively 6x speedup. My program never runs faster than 2x speedup on this 16 core Sunfire Xeon box, for any number of threads from 2-16. Running 16 copies of my program single threaded runs perfectly, all 16 running at once at full speed. top shows 1600% of CPUs allocated. /proc/cpuinfo shows all 16 cores running at full 2.9GHz speed (not low frequency idle speed of 1.6GHz) There's 48GB of RAM free, it is not swapping. What's happening? Is there some process CPU limit policy? How could I measure it if so? What else could explain this behavior? Thanks for your ideas to solve this, the Great Xeon Slowdown Mystery of 2010!

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  • Windows 7 & Virtual PC and Internet (gateway) problems on host PC

    - by Mufasa
    I upgraded to Windows 7 on a PC that is a few years old. The CPU was one revision away from having Hyper-V on it. So, I had to install Microsoft Virtual PC 2007 (v6.0.156.0) to run full XP instances instead of the seamless XP virtualization that is advertised so much. That's fine though; the 'older' version is useful since I use it to run different versions of the whole XP/IE stack for testing. (I'm a web developer.) ...And for the one 16-bit application we still use at the office for scheduling. * sigh * The virtual instances work fine, including networking. My issue is that after a reboot or coming out of sleep mode, my host Windows 7 won't connect to the Internet. It will connect to the local network fine. If I disable the "Virtual Machine Network Services" item (I'll call "VMNS" from here on) in the LAN Connection properties box, it starts working. But than the Virtual PC instances lose their network connectivity. If I re-enable VMNS again in the same instance, everything works (Internet on host and in the virtualized instances). But after the next reboot/sleep cycle this starts over. The route table gave me a clue though. When doing a cycle w/ VMNS enabled: IPv4 Route Table =========================================================================== Active Routes: Network Destination Netmask Gateway Interface Metric 0.0.0.0 0.0.0.0 On-link 10.0.3.51 20 0.0.0.0 0.0.0.0 10.0.10.10 10.0.3.51 276 ... After VMNS is disabled, the first route goes away. I assume that is for VMNS to intercept virtualized instance's network connections and forward them correctly? Just a guess though. More info: I checked my Firewall settings and Services (because I'm sort of a control nazi and turn off a lot) but couldn't find anything that made sense and if turned on changed anything. So it might be something there I'm missing, but I don't know what. My current hacked solution: So, I figured I'd mess with the routes myself to see if that helped, it did. If I run a route delete 0.0.0.0 on the universal (0.0.0.0) gateway routes, and add back in just the 2nd line with route add 0.0.0.0 mask 0.0.0.0 10.0.10.10--the one that points to my actual gateway (10.0.10.10)--then I don't have to mess with the disable/enable cycle of VMNS, and everything works. Running those two commands is faster then bringing up connection options and disabling and re-enabling VMNS, but I still don't want to have use that hack script every boot either. (Oh, and I also tried messing with hard-coding TCP/IP settings in my network adapter, including setting high metrics, etc., but that didn't help either.) Any suggestions on the right way to fix this?

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  • Parallelism in .NET – Part 16, Creating Tasks via a TaskFactory

    - by Reed
    The Task class in the Task Parallel Library supplies a large set of features.  However, when creating the task, and assigning it to a TaskScheduler, and starting the Task, there are quite a few steps involved.  This gets even more cumbersome when multiple tasks are involved.  Each task must be constructed, duplicating any options required, then started individually, potentially on a specific scheduler.  At first glance, this makes the new Task class seem like more work than ThreadPool.QueueUserWorkItem in .NET 3.5. In order to simplify this process, and make Tasks simple to use in simple cases, without sacrificing their power and flexibility, the Task Parallel Library added a new class: TaskFactory. The TaskFactory class is intended to “Provide support for creating and scheduling Task objects.”  Its entire purpose is to simplify development when working with Task instances.  The Task class provides access to the default TaskFactory via the Task.Factory static property.  By default, TaskFactory uses the default TaskScheduler to schedule tasks on a ThreadPool thread.  By using Task.Factory, we can automatically create and start a task in a single “fire and forget” manner, similar to how we did with ThreadPool.QueueUserWorkItem: Task.Factory.StartNew(() => this.ExecuteBackgroundWork(myData) ); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This provides us with the same level of simplicity we had with ThreadPool.QueueUserWorkItem, but even more power.  For example, we can now easily wait on the task: // Start our task on a background thread var task = Task.Factory.StartNew(() => this.ExecuteBackgroundWork(myData) ); // Do other work on the main thread, // while the task above executes in the background this.ExecuteWorkSynchronously(); // Wait for the background task to finish task.Wait(); TaskFactory simplifies creation and startup of simple background tasks dramatically. In addition to using the default TaskFactory, it’s often useful to construct a custom TaskFactory.  The TaskFactory class includes an entire set of constructors which allow you to specify the default configuration for every Task instance created by that factory.  This is particularly useful when using a custom TaskScheduler.  For example, look at the sample code for starting a task on the UI thread in Part 15: // Given the following, constructed on the UI thread // TaskScheduler uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); // When inside a background task, we can do string status = GetUpdatedStatus(); (new Task(() => { statusLabel.Text = status; })) .Start(uiScheduler); This is actually quite a bit more complicated than necessary.  When we create the uiScheduler instance, we can use that to construct a TaskFactory that will automatically schedule tasks on the UI thread.  To do that, we’d create the following on our main thread, prior to constructing our background tasks: // Construct a task scheduler from the current SynchronizationContext (UI thread) var uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); // Construct a new TaskFactory using our UI scheduler var uiTaskFactory = new TaskFactory(uiScheduler); If we do this, when we’re on a background thread, we can use this new TaskFactory to marshal a Task back onto the UI thread.  Our previous code simplifies to: // When inside a background task, we can do string status = GetUpdatedStatus(); // Update our UI uiTaskFactory.StartNew( () => statusLabel.Text = status); Notice how much simpler this becomes!  By taking advantage of the convenience provided by a custom TaskFactory, we can now marshal to set data on the UI thread in a single, clear line of code!

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  • An easy way to create Side by Side registrationless COM Manifests with Visual Studio

    - by Rick Strahl
    Here's something I didn't find out until today: You can use Visual Studio to easily create registrationless COM manifest files for you with just a couple of small steps. Registrationless COM lets you use COM component without them being registered in the registry. This means it's possible to deploy COM components along with another application using plain xcopy semantics. To be sure it's rarely quite that easy - you need to watch out for dependencies - but if you know you have COM components that are light weight and have no or known dependencies it's easy to get everything into a single folder and off you go. Registrationless COM works via manifest files which carry the same name as the executable plus a .manifest extension (ie. yourapp.exe.manifest) I'm going to use a Visual FoxPro COM object as an example and create a simple Windows Forms app that calls the component - without that component being registered. Let's take a walk down memory lane… Create a COM Component I start by creating a FoxPro COM component because that's what I know and am working with here in my legacy environment. You can use VB classic or C++ ATL object if that's more to your liking. Here's a real simple Fox one: DEFINE CLASS SimpleServer as Session OLEPUBLIC FUNCTION HelloWorld(lcName) RETURN "Hello " + lcName ENDDEFINE Compile it into a DLL COM component with: BUILD MTDLL simpleserver FROM simpleserver RECOMPILE And to make sure it works test it quickly from Visual FoxPro: server = CREATEOBJECT("simpleServer.simpleserver") MESSAGEBOX( server.HelloWorld("Rick") ) Using Visual Studio to create a Manifest File for a COM Component Next open Visual Studio and create a new executable project - a Console App or WinForms or WPF application will all do. Go to the References Node Select Add Reference Use the Browse tab and find your compiled DLL to import  Next you'll see your assembly in the project. Right click on the reference and select Properties Click on the Isolated DropDown and select True Compile and that's all there's to it. Visual Studio will create a App.exe.manifest file right alongside your application's EXE. The manifest file created looks like this: xml version="1.0" encoding="utf-8"? assembly xsi:schemaLocation="urn:schemas-microsoft-com:asm.v1 assembly.adaptive.xsd" manifestVersion="1.0" xmlns:asmv1="urn:schemas-microsoft-com:asm.v1" xmlns:asmv2="urn:schemas-microsoft-com:asm.v2" xmlns:asmv3="urn:schemas-microsoft-com:asm.v3" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" xmlns:co.v1="urn:schemas-microsoft-com:clickonce.v1" xmlns:co.v2="urn:schemas-microsoft-com:clickonce.v2" xmlns="urn:schemas-microsoft-com:asm.v1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" assemblyIdentity name="App.exe" version="1.0.0.0" processorArchitecture="x86" type="win32" / file name="simpleserver.DLL" asmv2:size="27293" hash xmlns="urn:schemas-microsoft-com:asm.v2" dsig:Transforms dsig:Transform Algorithm="urn:schemas-microsoft-com:HashTransforms.Identity" / dsig:Transforms dsig:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" / dsig:DigestValuepuq+ua20bbidGOWhPOxfquztBCU=dsig:DigestValue hash typelib tlbid="{f10346e2-c9d9-47f7-81d1-74059cc15c3c}" version="1.0" helpdir="" resourceid="0" flags="HASDISKIMAGE" / comClass clsid="{af2c2811-0657-4264-a1f5-06d033a969ff}" threadingModel="Apartment" tlbid="{f10346e2-c9d9-47f7-81d1-74059cc15c3c}" progid="simpleserver.SimpleServer" description="simpleserver.SimpleServer" / file assembly Now let's finish our super complex console app to test with: using System; using System.Collections.Generic; using System.Text; namespace ConsoleApplication1 {     class Program     {         static voidMain(string[] args)         { Type type = Type.GetTypeFromProgID("simpleserver.simpleserver",true); dynamic server = Activator.CreateInstance(type); Console.WriteLine(server.HelloWorld("rick")); Console.ReadLine(); } } } Now run the Console Application… As expected that should work. And why not? The COM component is still registered, right? :-) Nothing tricky about that. Let's unregister the COM component and then re-run and see what happens. Go to the Command Prompt Change to the folder where the DLL is installed Unregister with: RegSvr32 -u simpleserver.dll      To be sure that the COM component no longer works, check it out with the same test you used earlier (ie. o = CREATEOBJECT("SimpleServer.SimpleServer") in your development environment or VBScript etc.). Make sure you run the EXE and you don't re-compile the application or else Visual Studio will complain that it can't find the COM component in the registry while compiling. In fact now that we have our .manifest file you can remove the COM object from the project. When you run run the EXE from Windows Explorer or a command prompt to avoid the recompile. Watch out for embedded Manifest Files Now recompile your .NET project and run it… and it will most likely fail! The problem is that .NET applications by default embeds a manifest file into the compiled EXE application which results in the externally created manifest file being completely ignored. Only one manifest can be applied at a time and the compiled manifest takes precedency. Uh, thanks Visual Studio - not very helpful… Note that if you use another development tool like Visual FoxPro to create your EXE this won't be an issue as long as the tool doesn't automatically add a manifest file. Creating a Visual FoxPro EXE for example will work immediately with the generated manifest file as is. If you are using .NET and Visual Studio you have a couple of options of getting around this: Remove the embedded manifest file Copy the contents of the generated manifest file into a project manifest file and compile that in To remove an embedded manifest in a Visual Studio project: Open the Project Properties (Alt-Enter on project node) Go down to Resources | Manifest and select | Create Application without a Manifest   You can now add use the external manifest file and it will actually be respected when the app runs. The other option is to let Visual Studio create the manifest file on disk and then explicitly add the manifest file into the project. Notice on the dialog above I did this for app.exe.manifest and the manifest actually shows up in the list. If I select this file it will be compiled into the EXE and be used in lieu of any external files and that works as well. Remove the simpleserver.dll reference so you can compile your code and run the application. Now it should work without COM registration of the component. Personally I prefer external manifests because they can be modified after the fact - compiled manifests are evil in my mind because they are immutable - once they are there they can't be overriden or changed. So I prefer an external manifest. However, if you are absolutely sure nothing needs to change and you don't want anybody messing with your manifest, you can also embed it. The option to either is there. Watch for Manifest Caching While working trying to get this to work I ran into some problems at first. Specifically when it wasn't working at first (due to the embedded schema) I played with various different manifest layouts in different files etc.. There are a number of different ways to actually represent manifest files including offloading to separate folder (more on that later). A few times I made deliberate errors in the schema file and I found that regardless of what I did once the app failed or worked no amount of changing of the manifest file would make it behave differently. It appears that Windows is caching the manifest data for a given EXE or DLL. It takes a restart or a recompile of either the EXE or the DLL to clear the caching. Recompile your servers in order to see manifest changes unless there's an outright failure of an invalid manifest file. If the app starts the manifest is being read and caches immediately. This can be very confusing especially if you don't know that it's happening. I found myself always recompiling the exe after each run and before making any changes to the manifest file. Don't forget about Runtimes of COM Objects In the example I used above I used a Visual FoxPro COM component. Visual FoxPro is a runtime based environment so if I'm going to distribute an application that uses a FoxPro COM object the runtimes need to be distributed as well. The same is true of classic Visual Basic applications. Assuming that you don't know whether the runtimes are installed on the target machines make sure to install all the additional files in the EXE's directory alongside the COM DLL. In the case of Visual FoxPro the target folder should contain: The EXE  App.exe The Manifest file (unless it's compiled in) App.exe.manifest The COM object DLL (simpleserver.dll) Visual FoxPro Runtimes: VFP9t.dll (or VFP9r.dll for non-multithreaded dlls), vfp9rENU.dll, msvcr71.dll All these files should be in the same folder. Debugging Manifest load Errors If you for some reason get your manifest loading wrong there are a couple of useful tools available - SxSTrace and SxSParse. These two tools can be a huge help in debugging manifest loading errors. Put the following into a batch file (SxS_Trace.bat for example): sxstrace Trace -logfile:sxs.bin sxstrace Parse -logfile:sxs.bin -outfile:sxs.txt Then start the batch file before running your EXE. Make sure there's no caching happening as described in the previous section. For example, if I go into the manifest file and explicitly break the CLSID and/or ProgID I get a detailed report on where the EXE is looking for the manifest and what it's reading. Eventually the trace gives me an error like this: INFO: Parsing Manifest File C:\wwapps\Conf\SideBySide\Code\app.EXE.     INFO: Manifest Definition Identity is App.exe,processorArchitecture="x86",type="win32",version="1.0.0.0".     ERROR: Line 13: The value {AAaf2c2811-0657-4264-a1f5-06d033a969ff} of attribute clsid in element comClass is invalid. ERROR: Activation Context generation failed. End Activation Context Generation. pinpointing nicely where the error lies. Pay special attention to the various attributes - they have to match exactly in the different sections of the manifest file(s). Multiple COM Objects The manifest file that Visual Studio creates is actually quite more complex than is required for basic registrationless COM object invokation. The manifest file can be simplified a lot actually by stripping off various namespaces and removing the type library references altogether. Here's an example of a simplified manifest file that actually includes references to 2 COM servers: xml version="1.0" encoding="utf-8"? assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" assemblyIdentity name="App.exe" version="1.0.0.0" processorArchitecture="x86" type="win32" / file name="simpleserver.DLL" comClass clsid="{af2c2811-0657-4264-a1f5-06d033a969ff}" threadingModel="Apartment" progid="simpleserver.SimpleServer" description="simpleserver.SimpleServer" / file file name = "sidebysidedeploy.dll" comClass clsid="{EF82B819-7963-4C36-9443-3978CD94F57C}" progid="sidebysidedeploy.SidebysidedeployServer" description="SidebySideDeploy Server" threadingModel="apartment" / file assembly Simple enough right? Routing to separate Manifest Files and Folders In the examples above all files ended up in the application's root folder - all the DLLs, support files and runtimes. Sometimes that's not so desirable and you can actually create separate manifest files. The easiest way to do this is to create a manifest file that 'routes' to another manifest file in a separate folder. Basically you create a new 'assembly identity' via a named id. You can then create a folder and another manifest with the id plus .manifest that points at the actual file. In this example I create: App.exe.manifest A folder called App.deploy A manifest file in App.deploy All DLLs and runtimes in App.deploy Let's start with that master manifest file. This file only holds a reference to another manifest file: App.exe.manifest xml version="1.0" encoding="UTF-8" standalone="yes"? assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" assemblyIdentity name="App.exe" version="1.0.0.0" processorArchitecture="x86" type="win32" / dependency dependentAssembly assemblyIdentity name="App.deploy" version="1.0.0.0" type="win32" / dependentAssembly dependency assembly   Note this file only contains a dependency to App.deploy which is another manifest id. I can then create App.deploy.manifest in the current folder or in an App.deploy folder. In this case I'll create App.deploy and in it copy the DLLs and support runtimes. I then create App.deploy.manifest. App.deploy.manifest xml version="1.0" encoding="UTF-8" standalone="yes"? assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" assemblyIdentity name="App.deploy" type="win32" version="1.0.0.0" / file name="simpleserver.DLL" comClass clsid="{af2c2811-0657-4264-a1f5-06d033a969ff}" threadingModel="Apartment" progid="simpleserver.SimpleServer" description="simpleserver.SimpleServer" / file file name="sidebysidedeploy.dll" comClass clsid="{EF82B819-7963-4C36-9443-3978CD94F57C}" threadingModel="Apartment" progid="sidebysidedeploy.SidebysidedeployServer" description="SidebySideDeploy Server" / file assembly   In this manifest file I then host my COM DLLs and any support runtimes. This is quite useful if you have lots of DLLs you are referencing or if you need to have separate configuration and application files that are associated with the COM object. This way the operation of your main application and the COM objects it interacts with is somewhat separated. You can see the two folders here:   Routing Manifests to different Folders In theory registrationless COM should be pretty easy in painless - you've seen the configuration manifest files and it certainly doesn't look very complicated, right? But the devil's in the details. The ActivationContext API (SxS - side by side activation) is very intolerant of small errors in the XML or formatting of the keys, so be really careful when setting up components, especially if you are manually editing these files. If you do run into trouble SxsTrace/SxsParse are a huge help to track down the problems. And remember that if you do have problems that you'll need to recompile your EXEs or DLLs for the SxS APIs to refresh themselves properly. All of this gets even more fun if you want to do registrationless COM inside of IIS :-) But I'll leave that for another blog post…© Rick Strahl, West Wind Technologies, 2005-2011Posted in COM  .NET  FoxPro   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • CodePlex Daily Summary for Thursday, February 24, 2011

    CodePlex Daily Summary for Thursday, February 24, 2011Popular ReleasesInstant Feature Builder for Visual Studio 2010: Instant Feature Builder 1.2: This is the binary version of the Instant Feature Builder. Once downloaded, double click to install into Visual Studio. Version 1.2 fixes: Rename FX to IFB to shorten path lengths Fix issue in ExecuteCommand Fix issue to workaround problem with VS Template writer The Instant Feature Builder is a tool which enables you, via drag-and-drop, to build a specific type of Visual Studio extension (VSIX) known as a Feature Extension. A Feature Extension packages project and/or item templates,...DirectQ: Release 1.8.7 (Beta): Beta release of 1.8.7 to get feedback on what works well, what doesn't work well, and what doesn't work at all. D3D9 hardware with ps2.0 a must. Faster, more streamlined and more integrated rendering capabilities with additional MP features and support.Smartkernel: Smartkernel: ????,??????Chiave File Encryption: Chiave 0.9.1: Application for file encryption and decryption using 512 Bit rijndael encyrption algorithm with simple to use UI. Its written in C# and compiled in .Net version 3.5. It incorporates features of Windows 7 like Jumplists, Taskbar progress and Aero Glass. Change Log from 0.9 Beta to 0.9.1: ======================= >Added option for system shutdown, sleep, hibernate after operation completed. >Minor Changes to the UI. >Numerous Bug fixes. Feedbacks are Welcome!....DotNetNuke® Store: 03.00.00: What's New in this release? IMPORTANT: this version requires DotNetNuke 04.06.02 or higher! DO NOT REPORT BUGS HERE IN THE ISSUE TRACKER, INSTEAD USE THE DotNetNuke Store Forum! This version is the same code base as the version 02.01.51 RC, just some cleaning and source code release before submition to the release tracker for "official" release.ClosedXML - The easy way to OpenXML: ClosedXML 0.45.2: New on this release: 1) Added data validation. See Data Validation 2) Deleting or clearing cells deletes the hyperlinks too. New on v0.45.1 1) Fixed issues 6237, 6240 New on v0.45.2 1) Fixed issues 6257, 6266 New Examples Data ValidationOMEGA CMS: OMEGA CMA - Alpha 0.2: A few fixes for OMEGA Framework (DLL) A few tweeks for OMEGA CMSCoding4Fun Tools: Coding4Fun.Phone.Toolkit v1.2: New control, Toast Prompt! Removed progress bar since Silverlight Toolkit Feb 2010 has it.Umbraco CMS: Umbraco 4.7: Service release fixing 31 issues. A full changelog will be available with the final stable release of 4.7 Important when upgradingUpgrade as if it was a patch release (update /bin, /umbraco and /umbraco_client). For general upgrade information follow the guide found at http://our.umbraco.org/wiki/install-and-setup/upgrading-an-umbraco-installation 4.7 requires the .NET 4.0 framework Web.Config changes Update the web web.config to include the 4 changes found in (they're clearly marked in...HubbleDotNet - Open source full-text search engine: V1.1.0.0: Add Sqlite3 DBAdapter Add App Report when Query Cache is Collecting. Improve the performance of index through Synchronize. Add top 0 feature so that we can only get count of the result. Improve the score calculating algorithm of match. Let the score of the record that match all items large then others. Add MySql DBAdapter Improve performance for multi-fields sort . Using hash table to access the Payload data. The version before used bin search. Using heap sort instead of qui...Xen: Graphics API for XNA: Xen 2.0: This is the final release of Xen; Xen 2.0. Xen 2.0 supports PC and Xbox 360 running XNA 4. The documentation download is coming soon Due to restrictions in XNA 4, Building Xen requires a DirectX 10 capable video card (Xen applications can still run on Windows Xp and DirectX 9 video cards)Silverlight????[???]: silverlight????[???]2.0: ???????,?????,????????silverlight??????。DBSourceTools: DBSourceTools_1.3.0.0: Release 1.3.0.0 Changed editors from FireEdit to ICSharpCode.TextEditor. Complete re-vamp of Intellisense ( further testing needed). Hightlight Field and Table Names in sql scripts. Added field dropdown on all tables and views in DBExplorer. Added data option for viewing data in Tables. Fixed comment / uncomment bug as reported by tareq. Included Synonyms in scripting engine ( nickt_ch ).IronPython: 2.7 Release Candidate 1: We are pleased to announce the first Release Candidate for IronPython 2.7. This release contains over two dozen bugs fixed in preparation for 2.7 Final. See the release notes for 60193 for details and what has already been fixed in the earlier 2.7 prereleases. - IronPython TeamCaliburn Micro: A Micro-Framework for WPF, Silverlight and WP7: Caliburn.Micro 1.0 RC: This is the official Release Candicate for Caliburn.Micro 1.0. The download contains the binaries, samples and VS templates. VS Templates The templates included are designed for situations where the Caliburn.Micro source needs to be embedded within a single project solution. This was targeted at government and other organizations that expressed specific requirements around using an open source project like this. NuGet This release does not have a corresponding NuGet package. The NuGet pack...Caliburn: A Client Framework for WPF and Silverlight: Caliburn 2.0 RC: This is the official Release Candidate for Caliburn 2.0. It contains all binaries, samples and generated code docs.Rawr: Rawr 4.0.20 Beta: Rawr is now web-based. The link to use Rawr4 is: http://elitistjerks.com/rawr.phpThis is the Cataclysm Beta Release. More details can be found at the following link http://rawr.codeplex.com/Thread/View.aspx?ThreadId=237262 As of the 4.0.16 release, you can now also begin using the new Downloadable WPF version of Rawr!This is a pre-alpha release of the WPF version, there are likely to be a lot of issues. If you have a problem, please follow the Posting Guidelines and put it into the Issue Trac...MiniTwitter: 1.66: MiniTwitter 1.66 ???? ?? ?????????? 2 ??????????????????? User Streams ?????????Windows Phone 7 Isolated Storage Explorer: WP7 Isolated Storage Explorer v1.0 Beta: Current release features:WPF desktop explorer client Visual Studio integrated tool window explorer client (Visual Studio 2010 Professional and above) Supported operations: Refresh (isolated storage information), Add Folder, Add Existing Item, Download File, Delete Folder, Delete File Explorer supports operations running on multiple remote applications at the same time Explorer detects application disconnect (1-2 second delay) Explorer confirms operation completed status Explorer d...Silverlight Toolkit: Silverlight for Windows Phone Toolkit - Feb 2011: Silverlight for Windows Phone Toolkit OverviewSilverlight for Windows Phone Toolkit offers developers additional controls for Windows Phone application development, designed to match the rich user experience of the Windows Phone 7. Suggestions? Features? Questions? Ask questions in the Create.msdn.com forum. Add bugs or feature requests to the Issue Tracker. Help us shape the Silverlight Toolkit with your feedback! Please clearly indicate that the work items and issues are for the phone t...New ProjectsCompetition Management Platform: Paragliding Competition Management PlatformCS424 B2 Group - Car Management: CS424 B2 Group - Car ManagementEMS: The main aim of the system to perform environment inventorization.EVVA: EVVA ist ein Softwareprojekt zur Unterstützung privater Arbeitsvermittler FileSocialVB: A library to work with the filesocial.com web site and API through VB.NET. This is actually an offshoot of the http://twittervb.codeplex.com project. Though smaller, this will lead to a more compact library.Hash Crack - IGProgram: Hash Crack is a software program for hashes and passwords cracking. Hash Crack use dictionary or set of symbols for hashes cracking, and also support pwdump file format for Windows passwords cracking NTHash MD4. MD2, MD4, MD5, SHA1, SHA256, SHA384, SHA512Imail Spammer Killer: Bots seem to love picking off the weak passwords of IpSwitch IMail v10 users and using SMTP auth to spam the world with their new found account access. This project is a windows service to isolate and stop this activity by disabling the violated user account as it occurs.JVS2USB: Montage permettant de relier une IO ( capcom / Sega ) sur un PC via l'USB !!Library Reminder: Library ReminderMAVI: mobile application for the visually impaired: bill recognition & tag and recognize objects based on a specific stickerMessage splliting without envelope in Biztalk 2009: Message splitting without envelope in Biztalk 2009. The project contains: - Source Code - Examples Article describing how to make it:Microsoft translator: Language translator designed to test Microsoft Translator web service API In Windows Phone 7 developed using Visual Studio 2010 in C#mrmuffin: Mr Muffin WP7 game for childrenNetwork Monitor: Simple application with a vu-meter style display of recent incoming network traffic. - Requires .NET 4, - Requires WinPCap (http://www.winpcap.org/) - Only tested to run under Windows 7NPhysics: NPhysics - Physical Data Types for .NETOpen SimRacing Results: Open SimRacing Results aims to provide an open standard for race results of PC SimRacing games (like iRacing, rFactor, NR2003, ...), allowing developers of league management systems to use a unique interface to get the results from, regardless of the simulation used.Orchard Image Gallery: Orchard Image Gallery project is intented to provide a Image Gallery content part and/or widget for the Orchard Project.Planning Poker for Windows Phone 7: Play planning poker on your Windows Phone 7.Publishing and consuming WCF in Biztalk 2009 and Visual Studio 2008: The file contains: Biztalk 2009 Project, C# Console Project, Example. Push Notification for Windows Phone 7 in php: WindowsPhonePushNotification enables you to use Microsoft Push Notification Service in phpQuksace Agjke: For more information, please visit <http://students.cs.tamu.edu/abe/IS_and_R/HW3/quksace%20agjke.html>. http://students.cs.tamu.edu/abe/IS_and_R/HW3/quksace%20agjke.html Read: a "GNU Make"-like utility for viewing Readme files: Read is a simple program to easily load and read README files on a UNIX-compliant system. It works in a similar way to GNU Make by searching a directory for a compatible file, in this case a Readme file, and loading it for reading using a text editor or viewer.SQL CE 3.5 persistence mapper for ECO IV: May need some adjustments for ECO V/VI, definitely needs some rewrite to support SQL CE 4.0 fullySQL Server Job Failure Notification System: A simple means of ensuring you know when SQLAgent jobs fail.SuperQuery: SuperQuery makes it easy to run the same batch of SQL across several databases on different SQL servers. SuperQuery supports all editions and versions of SQL Server from 2000 onwards. It is developed in C# using .NET 4 Client Profile.System.Net.Mail Extended: An Extension to the System.Net.Mail Namespace, adding a POP3 Client, Enhanced SMTP Client, IMAP Client, POP3 Server, SMTP Server, and IMAP Serve, all written in Visual C#.wow-combatlogs: A PowerShell module for working with combat logs generated by World of Warcraft.WPF UndoManager: WPF UndoManager provides a simple Undomanager on the base of WPF's CommandPattern. It use an implementation of the ICommand-interface to manage a history of actions.XO / TicTacToe game: Dynamic sized XO / TicTacToe game for Windows Phone 7 Build using Visual Studio 2010 and C#

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  • On Contract Employment

    - by kerry
    I am going to post about something I don’t post about a lot, the business side of development.  Scott at the antipimp does a good job of explaining how contracts work from a business perspective.  I am going to give a view from the ground. First, a little background on myself.  I have recently taken a 6 month contract after about 8 years of fulltime employment.  I have 2 kids, and a stay at home wife.  I took this contract opportunity because I wanted to try it on for size.  I have always wondered whether I would like doing contracts over fulltime employment.  So, in keeping with the theme of this blog I will write this down now so that I may reference it later. ALL jobs are temporary! Right now you may not realize it, most people simply ignore it, but EVERY job is temporary.  Everyone should be planning for life after the money stops coming in.  Sadly, most people do not.  Contracting pushes this issue to the forefront, making you deal with it.  After a month on a contract, I am happy to say that I am saving more than I ever saved in a fulltime position.  Hopefully, I will be ready in case of an extended window of unemployment between contracts. Networking I find it extremely gratifying getting to know people.  It is especially beneficial when moving to a new city.  What better way to go out and meet people in your field than to work a few contracts?  6 months of working beside someone and you get to know them pretty well.  This is one of my favorite aspects. Technical Agility Moving between IS shops takes (or molds you into) a flexible person.  You have to be able to go in and hit the ground running.  This means you need to be able to sit down and start work on a large codebase working in a language that you may or may not have that much experience in.  It is also an excellent way to learn new languages and broaden your technical skill set.  I took my current position to learn Ruby.  A month ago, I had only used it in passing, but now I am using it every day.  It’s a tragedy in this field when people start coding for the joy and love of coding, then become deeply entrenched in their companies methods and technologies that it becomes a just a job. Less Stress I am not talking about the kind of stress you get from a jackass boss.  I am talking about the kind of stress I (or others) experience about planning and future proofing your code.  Not saying I stay up at night worrying whether we have done it right, if that code I wrote today is going to bite me later, but it still creeps around in the dark recesses of my mind.  Careful though, I am not suggesting you write sloppy code; just defer any large architectural or design decisions to the ‘code owners’. Flexible Scheduling It makes me very happy to be able to cut out a few hours early on a Friday (provided the work is done) and start the weekend off early by going to the pool, or taking the kids to the park.  Contracting provides you this opportunity (mileage may vary).  Most of your fulltime brethren will not care, they will be jealous that they’re corporate policy prevents them from doing the same.  However, you must be mindful of situations where this is not appropriate, and don’t over do it.  You are there to work after all. Affirmation of Need Have you ever been stuck in a job where you thought you were underpaid?  Have you ever been in a position where you felt like there was not enough workload for you?  This is not a problem for contractors.  When you start a contract it is understood that you are needed, and the employer knows that you are happy with the terms. Contracting may not be for everyone.  But, if you develop a relationship with a good consulting firm, keep their clients happy, then they will keep you happy.  They want you to work almost as much as you do.  Just be sure and plan financially for any windows of unemployment.

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  • Backup options in SharePoint 2007

    - by sreejukg
    It is very important to make sure the server farm backup is taking properly, making sure that in case of any disaster, the administrator has the latest backup that can be used to restore. This articles addresses some of the options available for backup/restore in SharePoint 2007 Backup There are two options that can be utilized to take backup of SharePoint sites. Using SharePoint Central Administration website Using SharePoint central administration website, you can do backup/restore from user interface. Using central administration website you can back up the following · Server farm · Web application · Content databases Follow these steps to take backup of the server farm using central administration 1. Open Central administration website 2. Navigate to Operations -> Backup and Restore -> Perform a backup 3. Here you will have options to choose the item to back up. Select Farm (the top most item in the list) 4. Once you select the items to backup, click on “Continue to backup options” 5. Select “Full” as type of backup. 6. In the backup file location, enter the path where you need to store the backup. The path should be according to the UNC, for e.g. for c drive you may use \\server\c$\mybackupFolder 7. Click ok 8. Now you will be redirected to Backup and Restore Status page. This page shows the progress for the backup operation. You can use the refresh button to update the status of backup(this page will automatically refresh in every 30 seconds). Once completed you can find the files in the specified folder. Using STSADM website SharePoint comes with a STSADM command line tool. STSADM provides lot of administrative operations that can be performed on SharePoint 2007 sites. You can find STSADM command from the following location C:\Program Files\Common Files\Microsoft shared\web server extensions\12\bin (You may change the drive letter according to your installation) STSADM provides a method for performing the Office SharePoint Server 2007 administration tasks at the command line or by using batch files or scripts. STSADM provides access to operations not available by using the Central Administration site The general syntax for STSADM is as follows STSADM -operation Operation Name –parameter1 value1 –parameter2 value2 ……….. Using STSADM you can back up the following · Server farm · Web application · Content databases To perform any STSADM, operation you need to be a member of administrators group. Follow these steps to take backup of SharePoint server farm using STSADM tool. Note: make sure you are logged in to the computer where central administration website is installed. 1. Open the Command prompt (You should run command prompt with administrator privileges) 2. Change the working directory to C:\Program Files\Common Files\Microsoft shared\web server extensions\12\bin 3. Enter the command, then press enter Stsadm –o backup -directory <UNC path> -backupmethod full 4. You will get success / failure message once the command finishes. How to schedule the backup There is no option to schedule a backup using central administration site. Also there is no operation provided by STSADM to automate the backup. The farm administrators need to take backup in regular intervals. To achieve this, you can write a batch file that includes STSADM command to take full backup of the server. This batch file can be scheduled using windows task scheduler to execute in certain intervals. Sample of the batch file 1. Open notepad(or any other text editor) 2. Enter the following commands @echo off echo =============================================================== echo Back up the farm to <C:\backup> echo =============================================================== cd %COMMONPROGRAMFILES%\Microsoft Shared\web server extensions\12\BIN @echo off stsadm.exe -o backup -directory "<\backup>" -backupmethod full echo completed 3. Save the file with .bat extension You can schedule this batch file as you require. Other Options Using STSADM tool, you will be able to take backup for individual site collection. The syntax for this is stsadm -o backup -url <URL name for site collection> -filename <file name> [-overwrite] The explanations for the parameters are as follows. -url The url of the site collection you need to backup -filename The name of the backup file. E.g. c:\backup.bak -overwrite optional. Indicates if the filename specified exists, whether to overwrite or not. If you are creating the batch file for scheduling the backup for a site collection, you may need to specify the backup filename automatically created. It is an option that you can generate the filename with date so that you can keep backup for each day. e.g. The following commands can be utilized create a site collection backup. @echo off echo =============================================================== echo Back up the farm to <C:\backup> echo =============================================================== echo =============================================================== echo getting todays date to a variable echo =============================================================== @For /F "tokens=1,2,3 delims=/ " %%A in (‘Date /t’) do @( Set Day=%%A Set Month=%%B Set Year=%%C Set todayDate=%%C%%B%%A ) cd %COMMONPROGRAMFILES%\Microsoft Shared\web server extensions\12\BIN @echo off stsadm -o backup -url <sitecollection url> -filename \\ServerName\ShareName\Backup_%todayDate%.bak -overwrite echo completed To read more about backup STSADM operation, read this http://technet.microsoft.com/en-us/library/cc263441.aspx

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  • Sorting Algorithms

    - by MarkPearl
    General Every time I go back to university I find myself wading through sorting algorithms and their implementation in C++. Up to now I haven’t really appreciated their true value. However as I discovered this last week with Dictionaries in C# – having a knowledge of some basic programming principles can greatly improve the performance of a system and make one think twice about how to tackle a problem. I’m going to cover briefly in this post the following: Selection Sort Insertion Sort Shellsort Quicksort Mergesort Heapsort (not complete) Selection Sort Array based selection sort is a simple approach to sorting an unsorted array. Simply put, it repeats two basic steps to achieve a sorted collection. It starts with a collection of data and repeatedly parses it, each time sorting out one element and reducing the size of the next iteration of parsed data by one. So the first iteration would go something like this… Go through the entire array of data and find the lowest value Place the value at the front of the array The second iteration would go something like this… Go through the array from position two (position one has already been sorted with the smallest value) and find the next lowest value in the array. Place the value at the second position in the array This process would be completed until the entire array had been sorted. A positive about selection sort is that it does not make many item movements. In fact, in a worst case scenario every items is only moved once. Selection sort is however a comparison intensive sort. If you had 10 items in a collection, just to parse the collection you would have 10+9+8+7+6+5+4+3+2=54 comparisons to sort regardless of how sorted the collection was to start with. If you think about it, if you applied selection sort to a collection already sorted, you would still perform relatively the same number of iterations as if it was not sorted at all. Many of the following algorithms try and reduce the number of comparisons if the list is already sorted – leaving one with a best case and worst case scenario for comparisons. Likewise different approaches have different levels of item movement. Depending on what is more expensive, one may give priority to one approach compared to another based on what is more expensive, a comparison or a item move. Insertion Sort Insertion sort tries to reduce the number of key comparisons it performs compared to selection sort by not “doing anything” if things are sorted. Assume you had an collection of numbers in the following order… 10 18 25 30 23 17 45 35 There are 8 elements in the list. If we were to start at the front of the list – 10 18 25 & 30 are already sorted. Element 5 (23) however is smaller than element 4 (30) and so needs to be repositioned. We do this by copying the value at element 5 to a temporary holder, and then begin shifting the elements before it up one. So… Element 5 would be copied to a temporary holder 10 18 25 30 23 17 45 35 – T 23 Element 4 would shift to Element 5 10 18 25 30 30 17 45 35 – T 23 Element 3 would shift to Element 4 10 18 25 25 30 17 45 35 – T 23 Element 2 (18) is smaller than the temporary holder so we put the temporary holder value into Element 3. 10 18 23 25 30 17 45 35 – T 23   We now have a sorted list up to element 6. And so we would repeat the same process by moving element 6 to a temporary value and then shifting everything up by one from element 2 to element 5. As you can see, one major setback for this technique is the shifting values up one – this is because up to now we have been considering the collection to be an array. If however the collection was a linked list, we would not need to shift values up, but merely remove the link from the unsorted value and “reinsert” it in a sorted position. Which would reduce the number of transactions performed on the collection. So.. Insertion sort seems to perform better than selection sort – however an implementation is slightly more complicated. This is typical with most sorting algorithms – generally, greater performance leads to greater complexity. Also, insertion sort performs better if a collection of data is already sorted. If for instance you were handed a sorted collection of size n, then only n number of comparisons would need to be performed to verify that it is sorted. It’s important to note that insertion sort (array based) performs a number item moves – every time an item is “out of place” several items before it get shifted up. Shellsort – Diminishing Increment Sort So up to now we have covered Selection Sort & Insertion Sort. Selection Sort makes many comparisons and insertion sort (with an array) has the potential of making many item movements. Shellsort is an approach that takes the normal insertion sort and tries to reduce the number of item movements. In Shellsort, elements in a collection are viewed as sub-collections of a particular size. Each sub-collection is sorted so that the elements that are far apart move closer to their final position. Suppose we had a collection of 15 elements… 10 20 15 45 36 48 7 60 18 50 2 19 43 30 55 First we may view the collection as 7 sub-collections and sort each sublist, lets say at intervals of 7 10 60 55 – 20 18 – 15 50 – 45 2 – 36 19 – 48 43 – 7 30 10 55 60 – 18 20 – 15 50 – 2 45 – 19 36 – 43 48 – 7 30 (Sorted) We then sort each sublist at a smaller inter – lets say 4 10 55 60 18 – 20 15 50 2 – 45 19 36 43 – 48 7 30 10 18 55 60 – 2 15 20 50 – 19 36 43 45 – 7 30 48 (Sorted) We then sort elements at a distance of 1 (i.e. we apply a normal insertion sort) 10 18 55 60 2 15 20 50 19 36 43 45 7 30 48 2 7 10 15 18 19 20 30 36 43 45 48 50 55 (Sorted) The important thing with shellsort is deciding on the increment sequence of each sub-collection. From what I can tell, there isn’t any definitive method and depending on the order of your elements, different increment sequences may perform better than others. There are however certain increment sequences that you may want to avoid. An even based increment sequence (e.g. 2 4 8 16 32 …) should typically be avoided because it does not allow for even elements to be compared with odd elements until the final sort phase – which in a way would negate many of the benefits of using sub-collections. The performance on the number of comparisons and item movements of Shellsort is hard to determine, however it is considered to be considerably better than the normal insertion sort. Quicksort Quicksort uses a divide and conquer approach to sort a collection of items. The collection is divided into two sub-collections – and the two sub-collections are sorted and combined into one list in such a way that the combined list is sorted. The algorithm is in general pseudo code below… Divide the collection into two sub-collections Quicksort the lower sub-collection Quicksort the upper sub-collection Combine the lower & upper sub-collection together As hinted at above, quicksort uses recursion in its implementation. The real trick with quicksort is to get the lower and upper sub-collections to be of equal size. The size of a sub-collection is determined by what value the pivot is. Once a pivot is determined, one would partition to sub-collections and then repeat the process on each sub collection until you reach the base case. With quicksort, the work is done when dividing the sub-collections into lower & upper collections. The actual combining of the lower & upper sub-collections at the end is relatively simple since every element in the lower sub-collection is smaller than the smallest element in the upper sub-collection. Mergesort With quicksort, the average-case complexity was O(nlog2n) however the worst case complexity was still O(N*N). Mergesort improves on quicksort by always having a complexity of O(nlog2n) regardless of the best or worst case. So how does it do this? Mergesort makes use of the divide and conquer approach to partition a collection into two sub-collections. It then sorts each sub-collection and combines the sorted sub-collections into one sorted collection. The general algorithm for mergesort is as follows… Divide the collection into two sub-collections Mergesort the first sub-collection Mergesort the second sub-collection Merge the first sub-collection and the second sub-collection As you can see.. it still pretty much looks like quicksort – so lets see where it differs… Firstly, mergesort differs from quicksort in how it partitions the sub-collections. Instead of having a pivot – merge sort partitions each sub-collection based on size so that the first and second sub-collection of relatively the same size. This dividing keeps getting repeated until the sub-collections are the size of a single element. If a sub-collection is one element in size – it is now sorted! So the trick is how do we put all these sub-collections together so that they maintain their sorted order. Sorted sub-collections are merged into a sorted collection by comparing the elements of the sub-collection and then adjusting the sorted collection. Lets have a look at a few examples… Assume 2 sub-collections with 1 element each 10 & 20 Compare the first element of the first sub-collection with the first element of the second sub-collection. Take the smallest of the two and place it as the first element in the sorted collection. In this scenario 10 is smaller than 20 so 10 is taken from sub-collection 1 leaving that sub-collection empty, which means by default the next smallest element is in sub-collection 2 (20). So the sorted collection would be 10 20 Lets assume 2 sub-collections with 2 elements each 10 20 & 15 19 So… again we would Compare 10 with 15 – 10 is the winner so we add it to our sorted collection (10) leaving us with 20 & 15 19 Compare 20 with 15 – 15 is the winner so we add it to our sorted collection (10 15) leaving us with 20 & 19 Compare 20 with 19 – 19 is the winner so we add it to our sorted collection (10 15 19) leaving us with 20 & _ 20 is by default the winner so our sorted collection is 10 15 19 20. Make sense? Heapsort (still needs to be completed) So by now I am tired of sorting algorithms and trying to remember why they were so important. I think every year I go through this stuff I wonder to myself why are we made to learn about selection sort and insertion sort if they are so bad – why didn’t we just skip to Mergesort & Quicksort. I guess the only explanation I have for this is that sometimes you learn things so that you can implement them in future – and other times you learn things so that you know it isn’t the best way of implementing things and that you don’t need to implement it in future. Anyhow… luckily this is going to be the last one of my sorts for today. The first step in heapsort is to convert a collection of data into a heap. After the data is converted into a heap, sorting begins… So what is the definition of a heap? If we have to convert a collection of data into a heap, how do we know when it is a heap and when it is not? The definition of a heap is as follows: A heap is a list in which each element contains a key, such that the key in the element at position k in the list is at least as large as the key in the element at position 2k +1 (if it exists) and 2k + 2 (if it exists). Does that make sense? At first glance I’m thinking what the heck??? But then after re-reading my notes I see that we are doing something different – up to now we have really looked at data as an array or sequential collection of data that we need to sort – a heap represents data in a slightly different way – although the data is stored in a sequential collection, for a sequential collection of data to be in a valid heap – it is “semi sorted”. Let me try and explain a bit further with an example… Example 1 of Potential Heap Data Assume we had a collection of numbers as follows 1[1] 2[2] 3[3] 4[4] 5[5] 6[6] For this to be a valid heap element with value of 1 at position [1] needs to be greater or equal to the element at position [3] (2k +1) and position [4] (2k +2). So in the above example, the collection of numbers is not in a valid heap. Example 2 of Potential Heap Data Lets look at another collection of numbers as follows 6[1] 5[2] 4[3] 3[4] 2[5] 1[6] Is this a valid heap? Well… element with the value 6 at position 1 must be greater or equal to the element at position [3] and position [4]. Is 6 > 4 and 6 > 3? Yes it is. Lets look at element 5 as position 2. It must be greater than the values at [4] & [5]. Is 5 > 3 and 5 > 2? Yes it is. If you continued to examine this second collection of data you would find that it is in a valid heap based on the definition of a heap.

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