Search Results

Search found 2842 results on 114 pages for 'joel st martin'.

Page 70/114 | < Previous Page | 66 67 68 69 70 71 72 73 74 75 76 77  | Next Page >

  • What are some good questions (and good/bad answers) to ask at an interview to gauge the competency of the company/team?

    - by Wayne M
    I'm already familiar with the Joel Test, but it's been my experience that some of the questions there have the answers "massaged" to make the company seem better than it is. I've had several jobs in the past that, for instance, claimed they had a QA process and did unit testing, and what they really meant is "The programmers test the app, and test with the debugger and via trial-and-error."; they said they used SVN but they just lumped everything into one giant repository and had no concept of branching/merging or anything more complicated than updating and committing; said they can build in one step and what they really mean is it's "one step" to copy dozens of files by hand from the programmer's PC to the live server. How do you go about properly gauging a company's environment to make sure that it's a well-evolved company and not stuck on doing things a certain way because they've done it for years and they're ignorant of change? You can almost never ask to see their source code, so you're stuck trying to figure out if the interviewer's answer is accurate or BS to make the company seem good. Besides the Joel Test what are some other good questions to get the proper feel for a company, and more importantly what are some good and bad answers that could indicate a good or bad company? I mean something like (take at face value, please, it's all I could think of at short notice): Question: How does the software team apply the SOLID principles and Inversion of Control to their code? Good Answer: We adhere to SOLID wherever possible; we use TDD so it kind of forces us to write abstract, testable code. We use Ninject for our IoC container because it's fairly easy to configure - it was that or StructureMap but I find Ninject a bit more intuitive, and who doesn't like ninjas? You're not a pirate, are you? Bad Answer: Our code is pretty secure, yeah. And what's this Inversion of Control thing? I've never heard of it before. You see what I did there. The "good" answer uses facts to back it up and has a bit of "in crowd" humor; the bad answer shows complete ignorance of the question - not necessarily a bad thing if you are interviewing for a manger/director position, but a terrible answer and a huge red flag if you're interviewing as a developer and talking to a senior developer or manager! My biggest problem at the moment is being able to take a generic response and gauge whether it's the good or bad answer; more often than not it's the bad kind and I find myself frustrated almost from day one at the new job. I suppose I could name drop if I ask about specific things (e.g. "Do you write unit tests?" and if the answer is yes, ask if they use NUnit, MbUnit or something else; if they mention data access ask if they use a clean ORM like NHibernate or something more coupled like EF or Linq) but is there another way short of being resolute to actually call the interview on things (which will almost certainly result in not getting the job, but if they are skirting the question it's probably not a job I want).

    Read the article

  • Using EigenObjectRecognizer

    - by Meko
    Hi. I am trying make Facial recognition using Emgu Cv. And using EigenObjectRecognizer could I do it? Also is some one can explain that usage of it? because if there is a no same foto it also returns value. Here is example from Internet Image<Gray, Byte>[] trainingImages = new Image<Gray,Byte>[5]; trainingImages[0] = new Image<Gray, byte>("brad.jpg"); trainingImages[1] = new Image<Gray, byte>("david.jpg"); trainingImages[2] = new Image<Gray, byte>("foof.jpg"); trainingImages[3] = new Image<Gray, byte>("irfan.jpg"); trainingImages[4] = new Image<Gray, byte>("joel.jpg"); String[] labels = new String[] { "Brad", "David", "Foof", "Irfan" , "Joel"} MCvTermCriteria termCrit = new MCvTermCriteria(16, 0.001); EigenObjectRecognizer recognizer = new EigenObjectRecognizer( trainingImages, labels, 5000, ref termCrit); Image<Gray,Byte> testImage = new Image<Gray,Byte>("brad_test.jpg"); String label = recognizer.Recognize(testImage); Console.Write(label); It returns brad .But if I change photo in testimage it also retunrs some name or even Brad.Is it good for face recognition to use this method?Or is there any better method?

    Read the article

  • Using ASP .NET Membership and Profile with MVC, how can I create a user and set it to HttpContext.Cu

    - by Jeremy Gruenwald
    I've read the other questions on the topic of MVC membership and profiles, but I'm missing something. I implemented a custom Profile object in code as described by Joel here: http://stackoverflow.com/questions/426609/asp-net-membership-how-to-assign-profile-values I can't get it to work when I'm creating a new user, however. When I do this: Membership.CreateUser(userName, password); Roles.AddUserToRole(userName, "MyRole"); the user is created and added to a role in the database, but HttpContext.Current.User is still empty, and Membership.GetUser() returns null, so this (from Joel's code) doesn't work: static public AccountProfile CurrentUser { get { return (AccountProfile) (ProfileBase.Create(Membership.GetUser().UserName)); } } AccountProfile.CurrentUser.FullName = "Snoopy"; I've tried calling Membership.GetUser(userName) and setting Profile properties that way, but the set properties remain empty, and calling AccountProfile.CurrentUser(userName).Save() doesn't put anything in the database. I've also tried indicating that the user is valid & logged in, by calling Membership.ValidateUser, FormsAuthentication.SetAuthCookie, etc., but the current user is still null or anonymous (depending on the state of my browser cookies). I have the feeling I'm missing some essential piece of understanding about how Membership, Authentication, and Profiles fit together. Do I have to do a round trip before the current User will be populated? Any advice would be much appreciated.

    Read the article

  • How do I authenticate regarding EJB3 Container ?

    - by FMR
    I have my business classes protected by EJB3 security annotations, now I would like to call these methods from a Spring controller, how do I do it? edit I will add some information about my setup, I'm using Tomcat for the webcontainer and OpenEJB for embedding EJB into tomcat. I did not settle on any version of spring so it's more or less open to suggestions. edit current setup works this way : I have a login form + controller that puts a User pojo inside SessionContext. Each time someone access a secured part of the site, the application checks for the User pojo, if it's there check roles and then show the page, if it's not show a appropriate message or redirect to login page. Now the bussiness calls are made thanks to a call method inside User which bypass a probable security context which is a remix of this code found in openejb security examples : Caller managerBean = (Caller) context.lookup("ManagerBeanLocal"); managerBean.call(new Callable() { public Object call() throws Exception { Movies movies = (Movies) context.lookup("MoviesLocal"); movies.addMovie(new Movie("Quentin Tarantino", "Reservoir Dogs", 1992)); movies.addMovie(new Movie("Joel Coen", "Fargo", 1996)); movies.addMovie(new Movie("Joel Coen", "The Big Lebowski", 1998)); List<Movie> list = movies.getMovies(); assertEquals("List.size()", 3, list.size()); for (Movie movie : list) { movies.deleteMovie(movie); } assertEquals("Movies.getMovies()", 0, movies.getMovies().size()); return null; } });

    Read the article

  • Special Activities in the OTN Lounge

    - by Bob Rhubart
    What is the OTN Lounge? It's the place for Oracle OpenWorld and JavaOne attendees to hang out, get off your feet, rest up between sessions, recharge your laptop, tablet, or phone, connect with other community members, pick the brains of subject matter experts and community leaders, enjoy some refreshments (coffee and soft drinks in the morning, beer in the afternoon), and avoid the crowds by watching keynote presentations on a plasma screen. But in addition to general chillaxin' the OTN Lounge also hosts several special activities throughout the week… OTN Lounge Special Activities Sunday Oracle Social Network Developer Challenge Kick-off   (7:00pm - 8:30pm)Want to learn more about Oracle Social Network? Love working with APIs? Enter the Oracle Social Network Developer Challenge and build your dream integration with Oracle's secure, purposeful social network for business. Demonstrate your skills, work with the latest and greatest and compete for $500 in Amazon gift cards. Go to theappslab.com/osnregisterr Read and agree to the terms and rules. Register yourself with your name, corporate email address, and company. Watch your inbox for a confirmation email from Oracle Social Network. Start coding (individual or teams welcome) Show off your work to the judges in the OTN Lounge, Wednesday, 4:00pm - 6:00pm Monday (Lounge hours: 8:00am - 7:00pm) RAC Attack (9:00am - 1:00pm) Learn about Oracle Real Application Clustering (RAC) in this collaborative event. You'll work with experts from the IOUG RAC SIG to get an Oracle Database 11gR2 RAC cluster running inside a virtual machine. For more information: RAC attack at Oracle Open World (Pythian Blog) RAC Attack - Oracle Cluster Database at Home/Events (WikiBooks) Oracle Social Network Developer Challenge Office Hours (4:00pm - 8:00pm)Meet the people behind Oracle Social Network. Tuesday (Lounge hours: 8:00am - 7:00pm) RAC Attack (9:00am - 1:00pm) Oracle Social Network Developer Challenge Office Hours (4:30pm - 8:00pm) Oracle Database / Oracle Fusion Middleware Tweet Meet (4:30pm - 6:00pm) Free as in beer! Oracle Database and Oracle Fusion Middleware tweeters, gather in the OTN Lounge for refreshments and conversation with fellow tweeters and Oracle Database and Middleware experts. Wednesday (Lounge Hours: 8:00am - 6:00pm) RAC Attack (9:00am - 1:00pm) Oracle Social Network Developer Challenge Judging (4:00pm - 6:00pm) ADF Oracle ADF / Oracle Fusion Middleware Meet-up (4:30pm - 5:30pm) Join other Oracle ADF and Oracle Fusion Middleware developers and meet the product managers and engineers behind Oracle ADF, ADF Mobile, and ADF Essentials. Did we mention free beer? Thursday (Lounge Hours: 8:00am - 2:00pm) RAC Attack (9:00am - 1:00pm) The OTN Lounge is located in the Howard St .tent, located by no small coincidence on Howard St. between 3rd and 4th, directly between Moscone North and Moscone South. An Oracle OpenWorld or JavaOne conference badge is required for access to the OTN Lounge.

    Read the article

  • formula for replicating glTexGen in opengl es 2.0 glsl

    - by visualjc
    I also posted this on the main StackExchange, but this seems like a better place, but for give me for the double post if it shows up twice. I have been trying for several hours to implement a GLSL replacement for glTexGen with GL_OBJECT_LINEAR. For OpenGL ES 2.0. In Ogl GLSL there is the gl_TextureMatrix that makes this easier, but thats not available on OpenGL ES 2.0 / OpenGL ES Shader Language 1.0 Several sites have mentioned that this should be "easy" to do in a GLSL vert shader. But I just can not get it to work. My hunch is that I'm not setting the planes up correctly, or I'm missing something in my understanding. I've pored over the web. But most sites are talking about projected textures, I'm just looking to create UV's based on planar projection. The models are being built in Maya, have 50k polygons and the modeler is using planer mapping, but Maya will not export the UV's. So I'm trying to figure this out. I've looked at the glTexGen manpage information: g = p1xo + p2yo + p3zo + p4wo What is g? Is g the value of s in the texture2d call? I've looked at the site: http://www.opengl.org/wiki/Mathematics_of_glTexGen Another size explains the same function: coord = P1*X + P2*Y + P3*Z + P4*W I don't get how coord (an UV vec2 in my mind) is equal to the dot product (a scalar value)? Same problem I had before with "g". What do I set the plane to be? In my opengl c++ 3.0 code, I set it to [0, 0, 1, 0] (basically unit z) and glTexGen works great. I'm still missing something. My vert shader looks basically like this: WVPMatrix = World View Project Matrix. POSITION is the model vertex position. varying vec4 kOutBaseTCoord; void main() { gl_Position = WVPMatrix * vec4(POSITION, 1.0); vec4 sPlane = vec4(1.0, 0.0, 0.0, 0.0); vec4 tPlane = vec4(0.0, 1.0, 0.0, 0.0); vec4 rPlane = vec4(0.0, 0.0, 0.0, 0.0); vec4 qPlane = vec4(0.0, 0.0, 0.0, 0.0); kOutBaseTCoord.s = dot(vec4(POSITION, 1.0), sPlane); kOutBaseTCoord.t = dot(vec4(POSITION, 1.0), tPlane); //kOutBaseTCoord.r = dot(vec4(POSITION, 1.0), rPlane); //kOutBaseTCoord.q = dot(vec4(POSITION, 1.0), qPlane); } The frag shader precision mediump float; uniform sampler2D BaseSampler; varying mediump vec4 kOutBaseTCoord; void main() { //gl_FragColor = vec4(kOutBaseTCoord.st, 0.0, 1.0); gl_FragColor = texture2D(BaseSampler, kOutBaseTCoord.st); } I've tried texture2DProj in frag shader Here are some of the other links I've looked up http://www.gamedev.net/topic/407961-texgen-not-working-with-glsl-with-fixed-pipeline-is-ok/ Thank you in advance.

    Read the article

  • ntpd server always in 'INIT' mode

    - by Deepak
    I'm running ntpd server in my ubuntu (10.04) machine. But it is always stays in the 'INIT' state as shown below. lyra@ws07475:~$ ntpq -p remote refid st t when poll reach delay offset jitter ============================================================================== europium.canoni .INIT. 16 u - 1024 0 0.000 0.000 0.000 lyra@ws07475:~$ Of course, this means that it is not keeping time. How can I start 'ntpd' server properly ? Please help.

    Read the article

  • SQLAuthority News – Job Interviewing the Right Way (and for the Right Reasons) – Guest Post by Feodor Georgiev

    - by pinaldave
    Feodor Georgiev is a SQL Server database specialist with extensive experience of thinking both within and outside the box. He has wide experience of different systems and solutions in the fields of architecture, scalability, performance, etc. Feodor has experience with SQL Server 2000 and later versions, and is certified in SQL Server 2008. Feodor has written excellent article on Job Interviewing the Right Way. Here is his article in his own language. A while back I was thinking to start a blog post series on interviewing and employing IT personnel. At that time I had just read the ‘Smart and gets things done’ book (http://www.joelonsoftware.com/items/2007/06/05.html) and I was hyped up on some debatable topics regarding finding and employing the best people in the branch. I have no problem with hiring the best of the best; it’s just the definition of ‘the best of the best’ that makes things a bit more complicated. One of the fundamental books one can read on the topic of interviewing is the one mentioned above. If you have not read it, then you must do so; not because it contains the ultimate truth, and not because it gives the answers to most questions on the subject, but because the book contains an extensive set of questions about interviewing and employing people. Of course, a big part of these questions have different answers, depending on location, culture, available funds and so on. (What works in the US may not necessarily work in the Nordic countries or India, or it may work in a different way). The only thing that is valid regardless of any external factor is this: curiosity. In my belief there are two kinds of people – curious and not-so-curious; regardless of profession. Think about it – professional success is directly proportional to the individual’s curiosity + time of active experience in the field. (I say ‘active experience’ because vacations and any distractions do not count as experience :)  ) So, curiosity is the factor which will distinguish a good employee from the not-so-good one. But let’s shift our attention to something else for now: a few tips and tricks for successful interviews. Tip and trick #1: get your priorities straight. Your status usually dictates your priorities; for example, if the person looking for a job has just relocated to a new country, they might tend to ignore some of their priorities and overload others. In other words, setting priorities straight means to define the personal criteria by which the interview process is lead. For example, similar to the following questions can help define the criteria for someone looking for a job: How badly do I need a (any) job? Is it more important to work in a clean and quiet environment or is it important to get paid well (or both, if possible)? And so on… Furthermore, before going to the interview, the candidate should have a list of priorities, sorted by the most importance: e.g. I want a quiet environment, x amount of money, great helping boss, a desk next to a window and so on. Also it is a good idea to be prepared and know which factors can be compromised and to what extent. Tip and trick #2: the interview is a two-way street. A job candidate should not forget that the interview process is not a one-way street. What I mean by this is that while the employer is interviewing the potential candidate, the job seeker should not miss the chance to interview the employer. Usually, the employer and the candidate will meet for an interview and talk about a variety of topics. In a quality interview the candidate will be presented to key members of the team and will have the opportunity to ask them questions. By asking the right questions both parties will define their opinion about each other. For example, if the candidate talks to one of the potential bosses during the interview process and they notice that the potential manager has a hard time formulating a question, then it is up to the candidate to decide whether working with such person is a red flag for them. There are as many interview processes out there as there are companies and each one is different. Some bigger companies and corporates can afford pre-selection processes, 3 or even 4 stages of interviews, small companies usually settle with one interview. Some companies even give cognitive tests on the interview. Why not? In his book Joel suggests that a good candidate should be pampered and spoiled beyond belief with a week-long vacation in New York, fancy hotels, food and who knows what. For all I can imagine, an interview might even take place at the top of the Eifel tower (right, Mr. Joel, right?) I doubt, however, that this is the optimal way to capture the attention of a good employee. The ‘curiosity’ topic What I have learned so far in my professional experience is that opinions can be subjective. Plus, opinions on technology subjects can also be subjective. According to Joel, only hiring the best of the best is worth it. If you ask me, there is no such thing as best of the best, simply because human nature (well, aside from some physical limitations, like putting your pants on through your head :) ) has no boundaries. And why would it have boundaries? I have seen many curious and interesting people, naturally good at technology, though uninterested in it as one  can possibly be; I have also seen plenty of people interested in technology, who (in an ideal world) should have stayed far from it. At any rate, all of this sums up at the end to the ‘supply and demand’ factor. The interview process big-bang boils down to this: If there is a mutual benefit for both the employer and the potential employee to work together, then it all sorts out nicely. If there is no benefit, then it is much harder to get to a common place. Tip and trick #3: word-of-mouth is worth a thousand words Here I would just mention that the best thing a job candidate can get during the interview process is access to future team members or other employees of the new company. Nowadays the world has become quite small and everyone knows everyone. Look at LinkedIn, look at other professional networks and you will realize how small the world really is. Knowing people is a good way to become more approachable and to approach them. Tip and trick #4: Be confident. It is true that for some people confidence is as natural as breathing and others have to work hard to express it. Confidence is, however, a key factor in convincing the other side (potential employer or employee) that there is a great chance for success by working together. But it cannot get you very far if it’s not backed up by talent, curiosity and knowledge. Tip and trick #5: The right reasons What really bothers me in Sweden (and I am sure that there are similar situations in other countries) is that there is a tendency to fill quotas and to filter out candidates by criteria different from their skill and knowledge. In job ads I see quite often the phrases ‘positive thinker’, ‘team player’ and many similar hints about personality features. So my guess here is that discrimination has evolved to a new level. Let me clear up the definition of discrimination: ‘unfair treatment of a person or group on the basis of prejudice’. And prejudice is the ‘partiality that prevents objective consideration of an issue or situation’. In other words, there is not much difference whether a job candidate is filtered out by race, gender or by personality features – it is all a bad habit. And in reality, there is no proven correlation between the technology knowledge paired with skills and the personal features (gender, race, age, optimism). It is true that a significantly greater number of Darwin awards were given to men than to women, but I am sure that somewhere there is a paper or theory explaining the genetics behind this. J This topic actually brings to mind one of my favorite work related stories. A while back I was working for a big company with many teams involved in their processes. One of the teams was occupying 2 rooms – one had the team members and was full of light, colorful posters, chit-chats and giggles, whereas the other room was dark, lighted only by a single monitor with a quiet person in front of it. Later on I realized that the ‘dark room’ person was the guru and the ultimate problem-solving-brain who did not like the chats and giggles and hence was in a separate room. In reality, all severe problems which the chatty and cheerful team members could not solve and all emergencies were directed to ‘the dark room’. And thus all worked out well. The moral of the story: Personality has nothing to do with technology knowledge and skills. End of story. Summary: I’d like to stress the fact that there is no ultimately perfect candidate for a job, and there is no such thing as ‘best-of-the-best’. From my personal experience, the main criteria by which I measure people (co-workers and bosses) is the curiosity factor; I know from experience that the more curious and inventive a person is, the better chances there are for great achievements in their field. Related stories: (for extra credit) 1) Get your priorities straight. A while back as a consultant I was working for a few days at a time at different offices and for different clients, and so I was able to compare and analyze the work environments. There were two different places which I compared and recently I asked a friend of mine the following question: “Which one would you prefer as a work environment: a noisy office full of people, or a quiet office full of faulty smells because the office is rarely cleaned?” My friend was puzzled for a while, thought about it and said: “Hmm, you are talking about two different kinds of pollution… I will probably choose the second, since I can clean the workplace myself a bit…” 2) The interview is a two-way street. One time, during a job interview, I met a potential boss that had a hard time phrasing a question. At that particular time it was clear to me that I would not have liked to work under this person. According to my work religion, the properly asked question contains at least half of the answer. And if I work with someone who cannot ask a question… then I’d be doing double or triple work. At another interview, after the technical part with the team leader of the department, I was introduced to one of the team members and we were left alone for 5 minutes. I immediately jumped on the occasion and asked the blunt question: ‘What have you learned here for the past year and how do you like your job?’ The team member looked at me and said ‘Nothing really. I like playing with my cats at home, so I am out of here at 5pm and I don’t have time for much.’ I was disappointed at the time and I did not take the job offer. I wasn’t that shocked a few months later when the company went bankrupt. 3) The right reasons to take a job: personality check. A while back I was asked to serve as a job reference for a coworker. I agreed, and after some weeks I got a phone call from the company where my colleague was applying for a job. The conversation started with the manager’s question about my colleague’s personality and about their social skills. (You can probably guess what my internal reaction was… J ) So, after 30 minutes of pouring common sense into the interviewer’s head, we finally agreed on the fact that a shy or quiet personality has nothing to do with work skills and knowledge. Some years down the road my former colleague is taking the manager’s position as the manager is demoted to a different department. Reference: Feodor Georgiev, Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, Readers Contribution, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

    Read the article

  • Mobile Linux Gets Support From Chip Vendors

    <b>Hardware Central:</b> "The development of Linux on mobile devices may be poised to get a boost thanks to the formation of a new industry group called Linaro, backed by a consortium of chip vendors including ARM, Freescale, Texas Instruments, Samsung and ST-Ericsson."

    Read the article

  • Getting Dynamic in SSIS Queries

    - by ejohnson2010
    When you start working with SQL Server and SSIS, it isn’t long before you find yourself wishing you could change bits of SQL queries dynamically. Most commonly, I see people that want to change the date portion of a query so that you can limit your query to the last 30 days, for example. This can be done using a combination of expressions and variables. I will do this in two parts, first I will build a variable that will always contain the 1 st day of the previous month and then I will dynamically...(read more)

    Read the article

  • PTLQueue : a scalable bounded-capacity MPMC queue

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

    Read the article

  • National Give Camp Weekend - January 14-16, 2011

    - by MOSSLover
    What is a Give Camp?  I get asked this question constantly in the SharePoint Community.  About 3 years ago there was an event called "We Are Microsoft" in Dallas, TX.  A lady named, Toi Wright, gathered up a bunch of charities and gathered up a bunch of IT Professionals in the community.  They met for an entire weekend devising better ways to help these charities with 3 days projects.  None of these charities had in house IT staff or they were lacking.  The time these projects would save would help out other people in the long run.  The first give camp was really popular that a couple guys from Kansas City decided to come up with a give camp in the Kansas City regiona.  The event was called Coders 4 Charity.  I read Jeff Julian's post on the "We Are Microsoft" event that it inspired me to get involved.  i showed up to this event and we were split into teams.  On that team I met a couple really awsome guys: Blake Theiss, Lee Brandt, Tim Wright, and Joe Loux.  We created a SharePoint site for a boyscout troup.  It was my first exposure to Silverlight 1.1.  I had so much fun that I attended the event the next year and the St. Louis Coders 4 Charity.  Last year in 2010 when I moved i searched high and low.  Sure enough they had an event in Philadelphia.  I helped out with two SharePoint Projects for a team of firefighters and another charity.  This year there are a series of give camps around the U.S.  They have consolidated most of the give camps.  The first ever New York City Give Camp is on National Give Camp Day.  If you guys are interested I see there is a give camp in Philadelphia, St. Louis, Northwest Arkansas, Seattle, Atlanta, Houston, and more...Here is a link to the site I would definitely encourage you to get involved: http://givecamp.org/national-givecamp/.  Also, if you feel like it's only developer focused that's entirely wrong.  They need DBAs, Project Leads, Architects, and many other roles fulfilled aside from development.  It is a great experience to meet good people and help out a charity doing what we all love to do.  I strongle encourage getting involved in a give camp.  if you are coming to the NYC Give Camp I would love to meet you.  i will be there on Saturday somewhere in the morning until around dinner time.

    Read the article

  • DNN World 2011

    - by bdukes
    We’re on the plane flying back to St. Louis from DNN World 2011 .  I gave a presentation titled DNN 6 UI/UX Patterns , discussing the form patterns introduced in the administrative modules in DNN 6 (the new look and feel that you immediately noticed after logging into your new DNN 6 site).  Many folks asked about seeing the examples that I presented, and they are available as a repository on github, at https://github.com/bdukes/DNN-World-Demos .  This includes a series of small, one...(read more)

    Read the article

  • Set Up A Wii Internet Connection

    If you have a Nintendo Wii Internet connection, it will allow you to play games with friends across the world, download games, update your system, send email to friends, and more. With these given st... [Author: Susan Brown - Computers and Internet - May 08, 2010]

    Read the article

  • Data Education: Great Classes Coming to a City Near You

    - by Adam Machanic
    In case you haven't noticed, Data Education (the training company I started a couple of years ago) has expanded beyond the US northeast; we're currently offering courses with top trainers in both St. Louis and Chicago , as well as the Boston area. The courses are starting to fill up fast—not surprising when you consider we’re talking about experienced instructors like Kalen Delaney , Rob Farley , and Allan Hirt —but we have still have some room. We’re very excited about bringing the highest quality...(read more)

    Read the article

  • Digineer Is Hiring

    - by Christopher House
    My employer, Digineer is looking for BizTalk and SharePoint people.  If you or someone you know is looking for a great opportunity in the Minneapolis/St. Paul area, get in touch via the Contact link on this page.

    Read the article

  • Welcome

    - by 13DaysaWeek
    Greetings! Let me start with an introduction.  My name is Chris House.  I'm a consultant with Digineer, a management and technology consultant firm in the Twin Cities of Minneapolis/St. Paul, Minnesota.  My particular area of focus is on middle tier technologies such as BizTalk, WCF, etc. I'm looking forward to sharing some of the interesting tidbits I come across during the course of my work.

    Read the article

  • Un malware paralyse les systèmes de communication d'un réseau d'ambulances desservent 90 % de la Nouvelle-Zélande

    Un malware paralyse les systèmes de communication d'un réseau d'ambulances Desservent 90 % de la Nouvelle-Zélande Une attaque de malware a réussi de paralyser les systèmes de réponse automatisés de toute une constellation d'ambulances en Nouvelle-Zélande. Le blocage des centres de communication St John, qui desservent 90 % des ambulances au pays, les a contraints à allouer manuellement les ambulanciers avec des systèmes-radio classiques, et ce pendant plus de 24 heures. Les problèmes ont commencé mercredi passé quand un malware non identifié a infecté les systèmes des centres partout dans le pays, pourtant protégé par antivirus, précise Alan Goudge, manager des opér...

    Read the article

  • Inline template efficiency

    - by Darryl Gove
    I like inline templates, and use them quite extensively. Whenever I write code with them I'm always careful to check the disassembly to see that the resulting output is efficient. Here's a potential cause of inefficiency. Suppose we want to use the mis-named Leading Zero Detect (LZD) instruction on T4 (this instruction does a count of the number of leading zero bits in an integer register - so it should really be called leading zero count). So we put together an inline template called lzd.il looking like: .inline lzd lzd %o0,%o0 .end And we throw together some code that uses it: int lzd(int); int a; int c=0; int main() { for(a=0; a<1000; a++) { c=lzd(c); } return 0; } We compile the code with some amount of optimisation, and look at the resulting code: $ cc -O -xtarget=T4 -S lzd.c lzd.il $ more lzd.s .L77000018: /* 0x001c 11 */ lzd %o0,%o0 /* 0x0020 9 */ ld [%i1],%i3 /* 0x0024 11 */ st %o0,[%i2] /* 0x0028 9 */ add %i3,1,%i0 /* 0x002c */ cmp %i0,999 /* 0x0030 */ ble,pt %icc,.L77000018 /* 0x0034 */ st %i0,[%i1] What is surprising is that we're seeing a number of loads and stores in the code. Everything could be held in registers, so why is this happening? The problem is that the code is only inlined at the code generation stage - when the actual instructions are generated. Earlier compiler phases see a function call. The called functions can do all kinds of nastiness to global variables (like 'a' in this code) so we need to load them from memory after the function call, and store them to memory before the function call. Fortunately we can use a #pragma directive to tell the compiler that the routine lzd() has no side effects - meaning that it does not read or write to memory. The directive to do that is #pragma no_side_effect(<routine name), and it needs to be placed after the declaration of the function. The new code looks like: int lzd(int); #pragma no_side_effect(lzd) int a; int c=0; int main() { for(a=0; a<1000; a++) { c=lzd(c); } return 0; } Now the loop looks much neater: /* 0x0014 10 */ add %i1,1,%i1 ! 11 ! { ! 12 ! c=lzd(c); /* 0x0018 12 */ lzd %o0,%o0 /* 0x001c 10 */ cmp %i1,999 /* 0x0020 */ ble,pt %icc,.L77000018 /* 0x0024 */ nop

    Read the article

  • 'module' object has no attribute 'element_make_factory'

    - by Ronan Dejhero
    i have this code : import pygst import st, pygtk player_name = gst.element_make_factory("playbin", "Multimedia Player") player_name.set_property("uri", "../media/alert.mp3") player_name.set_state(gst.PLAYING) it keeps throwing me the following error : player_name = gst.element_make_factory("playbin", "Multimedia Player") AttributeError: 'module' object has no attribute 'element_make_factory' nay way to solve this and why is this happening ? if i print gst i get the following : <module 'gst' from '/usr/lib/python2.7/dist-packages/gst-0.10/gst/__init__.pyc'> so it is a module !

    Read the article

< Previous Page | 66 67 68 69 70 71 72 73 74 75 76 77  | Next Page >