Search Results

Search found 6559 results on 263 pages for 'parallel foreach'.

Page 180/263 | < Previous Page | 176 177 178 179 180 181 182 183 184 185 186 187  | Next Page >

• Is it possible to have asynchronous processing

  - by prashant2361

  Hi, I have a requirement where I need to send continuous updates to my clients. Client is browser in this case. We have some data which updates every sec, so once client connects to our server, we maintain a persistent connection and keep pushing data to the client. I am looking for suggestions of this implementation at the server end. Basically what I need is this: 1. client connects to server. I maintain the socket and metadata about the socket. metadata contains what updates need to be send to this client 2. server process now waits for new client connections 3. One other process will have the list of all the sockets opened and will go through each of them and send the updates if required. Can we do something like this in Apache module: 1. Apache process gets the new connection. It maintains the state for the connection. It keeps the state in some global memory and returns back to root process to signify that it is done so that it can accept the new connection 2. the Apache process though has returned the status to root process but it is also executing in parallel where it going through its global store and sending updates to the client, if any. So can a Apache process do these things: 1. Have more than one connection associated with it 2. Asynchronously waiting for new connection and at the same time processing the previous connections? Regards Prashant

  Read the article

• help me reason about F# threads

  - by Kevin Cantu

  In goofing around with some F# (via MonoDevelop), I have written a routine which lists files in a directory with one thread: let rec loop (path:string) = Array.append ( path |> Directory.GetFiles ) ( path |> Directory.GetDirectories |> Array.map loop |> Array.concat ) And then an asynchronous version of it: let rec loopPar (path:string) = Array.append ( path |> Directory.GetFiles ) ( let paths = path |> Directory.GetDirectories if paths <> [||] then [| for p in paths -> async { return (loopPar p) } |] |> Async.Parallel |> Async.RunSynchronously |> Array.concat else [||] ) On small directories, the asynchronous version works fine. On bigger directories (e.g. many thousands of directories and files), the asynchronous version seems to hang. What am I missing? I know that creating thousands of threads is never going to be the most efficient solution -- I only have 8 CPUs -- but I am baffled that for larger directories the asynchronous function just doesn't respond (even after a half hour). It doesn't visibly fail, though, which baffles me. Is there a thread pool which is exhausted? How do these threads actually work?

  Read the article

• How to calculate the normal of points on a 3D cubic Bézier curve given normals for its start and end points?

  - by Robert

  I'm trying to render a "3D ribbon" using a single 3D cubic Bézier curve to describe it (the width of the ribbon is some constant). The first and last control points have a normal vector associated with them (which are always perpendicular to the tangents at those points, and describe the surface normal of the ribbon at those points), and I'm trying to smoothly interpolate the normal vector over the course of the curve. For example, given a curve which forms the letter 'C', with the first and last control points both having surface normals pointing upwards, the ribbon should start flat, parallel to the ground, slowly turn, and then end flat again, facing the same way as the first control point. To do this "smoothly", it would have to face outwards half-way through the curve. At the moment (for this case), I've only been able to get all the surfaces facing upwards (and not outwards in the middle), which creates an ugly transition in the middle. It's quite hard to explain, I've attached some images below of this example with what it currently looks like (all surfaces facing upwards, sharp flip in the middle) and what it should look like (smooth transition, surfaces slowly rotate round). Silver faces represent the front, black faces the back. Incorrect, what it currently looks like: Correct, what it should look like: All I really need is to be able to calculate this "hybrid normal vector" for any point on the 3D cubic bézier curve, and I can generate the polygons no problem, but I can't work out how to get them to smoothly rotate round as depicted. Completely stuck as to how to proceed!

  Read the article

• Thread-safety of read-only memory access

  - by Edmund

  I've implemented the Barnes-Hut gravity algorithm in C as follows: Build a tree of clustered stars. For each star, traverse the tree and apply the gravitational forces from each applicable node. Update the star velocities and positions. Stage 2 is the most expensive stage, and so is implemented in parallel by dividing the set of stars. E.g. with 1000 stars and 2 threads, I have one thread processing the first 500 stars and the second thread processing the second 500. In practice this works: it speeds the computation by about 30% with two threads on a two-core machine, compared to the non-threaded version. Additionally, it yields the same numerical results as the original non-threaded version. My concern is that the two threads are accessing the same resource (namely, the tree) simultaneously. I have not added any synchronisation to the thread workers, so it's likely they will attempt to read from the same location at some point. Although access to the tree is strictly read-only I am not 100% sure it's safe. It has worked when I've tested it but I know this is no guarantee of correctness! Questions Do I need to make a private copy of the tree for each thread? Even if it is safe, are there performance problems of accessing the same memory from multiple threads?

  Read the article

• Is there a max recommended size on bundling js/css files due to chunking or packet loss?

  - by George Mauer

  So we all have heard that its good to bundle your javascript. Of course it is, but it seems to me that the story is too simple. See if my logic makes sense here. Obviously fewer HTTP requests is fewer round trips and hence better. However - and I don't know much about bare http - aren't http responses sent in chunks? And if a file is larger than one of those chunks doesn't it have to be downloaded as multiple (possibly synchronous?) round trips? As opposed to this, several requests for files just under the chunking size would arrive much quicker since modern web browsers download resources like javascripts in parallel. Even if chunking is not an issue, it seems like there would be some max recommended size just due to likelyhood of packet loss alone since a bundled file must wait till it is entirely downloaded to execute, versus the more lenient native rule that scripts must execute in order. Obviously there's also matters of browser caching and code volatility to consider but can someone confirm this or explain why I'm off base? Does anyone have any numbers to put to it?

  Read the article

• ADO.NET DataTable/DataRow Thread Safety

  - by Allen E. Scharfenberg

  Introduction A user reported to me this morning that he was having an issue with inconsistent results (namely, column values sometimes coming out null when they should not be) of some parallel execution code that we provide as part of an internal framework. This code has worked fine in the past and has not been tampered with lately, but it got me to thinking about the following snippet: Code Sample lock (ResultTable) { newRow = ResultTable.NewRow(); } newRow["Key"] = currentKey; foreach (KeyValuePair<string, object> output in outputs) { object resultValue = output.Value; newRow[output.Name] = resultValue != null ? resultValue : DBNull.Value; } lock (ResultTable) { ResultTable.Rows.Add(newRow); } (No guarantees that that compiles, hand-edited to mask proprietery information.) Explanation We have this cascading type of locking code other places in our system, and it works fine, but this is the first instance of cascading locking code that I have come across that interacts with ADO .NET. As we all know, members of framework objects are usually not thread safe (which is the case in this situation), but the cascading locking should ensure that we are not reading and writing to ResultTable.Rows concurrently. We are safe, right? Hypothesis Well, the cascading lock code does not ensure that we are not reading from or writing to ResultTable.Rows at the same time that we are assigning values to columns in the new row. What if ADO .NET uses some kind of buffer for assigning column values that is not thread safe--even when different object types are involved (DataTable vs. DataRow)? Has anyone run into anything like this before? I thought I would ask here at StackOverflow before beating my head against this for hours on end :) Conclusion Well, the consensus appears to be that changing the cascading lock to a full lock has resolved the issue. That is not the result that I expected, but the full lock version has not produced the issue after many, many, many tests. The lesson: be wary of cascading locks used on APIs that you do not control. Who knows what may be going on under the covers!

  Read the article

• Client-server synchronization pattern / algorithm?

  - by tm_lv

  I have a feeling that there must be client-server synchronization patterns out there. But i totally failed to google up one. Situation is quite simple - server is the central node, that multiple clients connect to and manipulate same data. Data can be split in atoms, in case of conflict, whatever is on server, has priority (to avoid getting user into conflict solving). Partial synchronization is preferred due to potentially large amounts of data. Are there any patterns / good practices for such situation, or if you don't know of any - what would be your approach? Below is how i now think to solve it: Parallel to data, a modification journal will be held, having all transactions timestamped. When client connects, it receives all changes since last check, in consolidated form (server goes through lists and removes additions that are followed by deletions, merges updates for each atom, etc.). Et voila, we are up to date. Alternative would be keeping modification date for each record, and instead of performing data deletes, just mark them as deleted. Any thoughts?

  Read the article

• Using SMO to call Database.ExecuteNonQuery() concurrently?

  - by JimDaniel

  I have been banging my head against the wall trying to figure out how I can run update scripts concurrently against multiple databases in a single SQL Server instance using SMO. Our environments have an ever-increasing number of databases which need updating, and iterating through one at a time is becoming a problem (too slow). From what I understand SMO does not support concurrent operations, and my tests have bore that out. There seems to be shared memory at the Server object level, for things like DataReader context, keeps throwing exceptions such as "reader is already open." I apologize for not having the exact exceptions I am getting. I will try to get them and update this post. I am no expert on SMO and just feeling my way through to be honest. Not really sure I am approaching it the right way, but it's something that has to be done, or our productivity will slow to a crawl. So how would you guys do something like this? Am I using the wrong technology with SMO? All I am wanting to do is execute sql scripts against databases in a single sql server instance in parallel. Thanks for any help you can give, Daniel

  Read the article

• Java: design for using many executors services and only few threads

  - by Guillaume

  I need to run in parallel multiple threads to perform some tests. My 'test engine' will have n tests to perform, each one doing k sub-tests. Each test result is stored for a later usage. So I have n*k processes that can be ran concurrently. I'm trying to figure how to use the java concurrent tools efficiently. Right now I have an executor service at test level and n executor service at sub test level. I create my list of Callables for the test level. Each test callable will then create another list of callables for the subtest level. When invoked a test callable will subsequently invoke all subtest callables test 1 subtest a1 subtest ...1 subtest k1 test n subtest a2 subtest ...2 subtest k2 call sequence: test manager create test 1 callable test1 callable create subtest a1 to k1 testn callable create subtest an to kn test manager invoke all test callables test1 callable invoke all subtest a1 to k1 testn callable invoke all subtest an to kn This is working fine, but I have a lot of new treads that are created. I can not share executor service since I need to call 'shutdown' on the executors. My idea to fix this problem is to provide the same fixed size thread pool to each executor service. Do you think it is a good design ? Do I miss something more appropriate/simple for doing this ?

  Read the article

• Threading calls to web service in a web service - (.net 2.0)

  - by Ryan Ternier

  Got a question regarding best practices for doing parallel web service calls, in a web service. Our portal will get a message, split that message into 2 messages, and then do 2 calls to our broker. These need to be on separate threads to lower the timeout. One solution is to do something similar to (pseudo code): XmlNode DNode = GetaGetDemoNodeSomehow(); XmlNode ENode = GetAGetElNodeSomehow(); XmlNode elResponse; XmlNode demResponse; Thread dThread = new Thread(delegate { //Web Service Call GetDemographics d = new GetDemographics(); demResponse = d.HIALRequest(DNode); }); Thread eThread = new Thread(delegate { //Web Service Call GetEligibility ge = new GetEligibility(); elResponse = ge.HIALRequest(ENode); }); dThread.Start(); eThread.Start(); dThread.Join(); eThread.Join(); //combine the resulting XML and return it. //Maybe throw a bit of logging in to make architecture happy Another option we thought of is to create a worker class, and pass it the service information and have it execute. This would allow us to have a bit more control over what is going on, but could add additional overhead. Another option brought up would be 2 asynchronous calls and manage the returns through a loop. When the calls are completed (success or error) the loop picks it up and ends. The portal service will be called about 50,000 times a day. I don't want to gold plate this sucker. I'm looking for something light weight. The services that are being called on the broker do have time out limits set, and are already heavily logged and audited, so I'm not worried on that part. This is .NET 2.0 , and as much as I would love to upgrade I can't right now. So please leave all the goodies of 2.0 out please.

  Read the article

• Finding the width of a directed acyclic graph... with only the ability to find parents

  - by Platinum Azure

  Hi guys, I'm trying to find the width of a directed acyclic graph... as represented by an arbitrarily ordered list of nodes, without even an adjacency list. The graph/list is for a parallel GNU Make-like workflow manager that uses files as its criteria for execution order. Each node has a list of source files and target files. We have a hash table in place so that, given a file name, the node which produces it can be determined. In this way, we can figure out a node's parents by examining the nodes which generate each of its source files using this table. That is the ONLY ability I have at this point, without changing the code severely. The code has been in public use for a while, and the last thing we want to do is to change the structure significantly and have a bad release. And no, we don't have time to test rigorously (I am in an academic environment). Ideally we're hoping we can do this without doing anything more dangerous than adding fields to the node. I'll be posting a community-wiki answer outlining my current approach and its flaws. If anyone wants to edit that, or use it as a starting point, feel free. If there's anything I can do to clarify things, I can answer questions or post code if needed. Thanks! EDIT: For anyone who cares, this will be in C. Yes, I know my pseudocode is in some horribly botched Python look-alike. I'm sort of hoping the language doesn't really matter.

  Read the article

• Help thinking "Pythony"

  - by Josh

  I'm brand new to Python and trying to learn it by replicating the following C++ function into python // determines which words in a vector consist of the same letters // outputs the words with the same letters on the same line void equivalentWords(vector <string> words, ofstream & outFile) { outFile << "Equivalent words\n"; // checkedWord is parallel to the words vector. It is // used to make sure each word is only displayed once. vector <bool> checkedWord (words.size(), false); for(int i = 0; i < words.size(); i++) { if (!checkedWord[i]){ outFile << " "; for(int j = i; j < words.size(); j++){ if(equivalentWords(words[i], words[j], outFile)) { outFile << words[j] << " "; checkedWord[j] = true; } } outFile << "\n"; } } } In my python code (below), rather than having a second vector, I have a list ("words") of lists of a string, a sorted list of the chars in the former string (because strings are immutable), and a bool (that tells if the word has been checked yet). However, I can't figure out how to change a value as you iterate through a list. for word, s_word, checked in words: if not checked: for word1, s_word1, checked1 in words: if s_word1 == s_word: checked1 = True # this doesn't work print word1, print "" Any help on doing this or thinking more "Pythony" is appreciated.

  Read the article

• R: Are there any alternatives to loops for subsetting from an optimization standpoint?

  - by Adam

  A recurring analysis paradigm I encounter in my research is the need to subset based on all different group id values, performing statistical analysis on each group in turn, and putting the results in an output matrix for further processing/summarizing. How I typically do this in R is something like the following: data.mat <- read.csv("...") groupids <- unique(data.mat$ID) #Assume there are then 100 unique groups results <- matrix(rep("NA",300),ncol=3,nrow=100) for(i in 1:100) { tempmat <- subset(data.mat,ID==groupids[i]) #Run various stats on tempmat (correlations, regressions, etc), checking to #make sure this specific group doesn't have NAs in the variables I'm using #and assign results to x, y, and z, for example. results[i,1] <- x results[i,2] <- y results[i,3] <- z } This ends up working for me, but depending on the size of the data and the number of groups I'm working with, this can take up to three days. Besides branching out into parallel processing, is there any "trick" for making something like this run faster? For instance, converting the loops into something else (something like an apply with a function containing the stats I want to run inside the loop), or eliminating the need to actually assign the subset of data to a variable?

  Read the article

• Releasing Autoreleasepool crashes on iOS 4.0 (and only on 4.0)

  - by samsam

  Hi there. I'm wondering what could cause this. I have several methods in my code that i call using performSelectorInBackground. Within each of these methods i have an Autoreleasepool that is being alloced/initialized at the beginning and released at the end of the method. this perfectly works on iOS 3.1.3 / 3.2 / 4.2 / 4.2.1 but it fataly crashes on iOS 4.0 with a EXC_BAD_ACCESS Exception that happens after calling [myPool release]. After I noticed this strange behaviour I was thinking about rewriting portions of my code and to make my app "less parallel" in case that the client os is 4.0. After I did that, the next point where the app crashed was within the ReachabilityCallback-Method from Apples Reachability "Framework". well, now I'm not quite sure what to do. The things i do within my threaded methods is pretty simple xml parsing (no cocoa calls or stuff that would affect the UI). After each method finishes it posts a notification which the coordinating-thread listens to and once all the parallelized methods have finished, the coordinating thread calls viewcontrollers etc... I have absolutely no clue what could cause this weird behaviour. Especially because Apples Code fails as well. any help is greatly appreciated! thanks, sam

  Read the article

• OpenMP in Fortran

  - by user345293

  I very rarely use fortran, however I have been tasked with taking legacy code rewriting it to run in parallel. I'm using gfortran for my compiler choice. I found some excellent resources at https://computing.llnl.gov/tutorials/openMP/ as well as a few others. My problem is this, before I add any OpenMP directives, if I simply compile the legacy program: gfortran Example1.F90 -o Example1 everything works, but turning on the openmp compiler option even without adding directives: gfortran -openmp Example1.F90 -o Example1 ends up with a Segmentation fault when I run the legacy program. Using smaller test programs that I wrote, I've successfully compiled other programs with -openmp that run on multiple threads, but I'm rather at a loss why enabling the option alone and no directives is resulting in a seg fault. I apologize if my question is rather simple. I could post code but it is rather long. It faults as I assign initial values: REAL, DIMENSION(da,da) :: uconsold REAL, DIMENSION(da,da,dr,dk) :: uconsolde ... uconsold=0.0 uconsolde=0.0 The first assignment to "uconsold" works fine, the second seems to be the source of the fault as when I comment the line out the next several lines execute merrily until "uconsolde" is used again. Thank you for any help in this matter.

  Read the article

• Standard term for a thread I/O reorder buffer?

  - by Crashworks

  I have a case where many threads all concurrently generate data that is ultimately written to one long, serial file. I need to somehow serialize these writes so that the file gets written in the right order. ie, I have an input queue of 2048 jobs j0..jn, each of which produces a chunk of data oi. The jobs run in parallel on, say, eight threads, but the output blocks have to appear in the file in the same order as the corresponding input blocks — the output file has to be in the order o0o1o2... The solution to this is pretty self evident: I need some kind of buffer that accumulates and writes the output blocks in the correct order, similar to a CPU reorder buffer in Tomasulo's algorithm, or to the way that TCP reassembles out-of-order packets before passing them to the application layer. Before I go code it, I'd like to do a quick literature search to see if there are any papers that have solved this problem in a particularly clever or efficient way, since I have severe realtime and memory constraints. I can't seem to find any papers describing this though; a Scholar search on every permutation of [threads, concurrent, reorder buffer, reassembly, io, serialize] hasn't yielded anything useful. I feel like I must just not be searching the right terms. Is there a common academic name or keyword for this kind of pattern that I can search on?

  Read the article

• SQL Server race condition issue with range lock

  - by Freek

  I'm implementing a queue in SQL Server (please no discussions about this) and am running into a race condition issue. The T-SQL of interest is the following: set transaction isolation level serializable begin tran declare @RecordId int declare @CurrentTS datetime2 set @CurrentTS=CURRENT_TIMESTAMP select top 1 @RecordId=Id from QueuedImportJobs with (updlock) where Status=@Status and (LeaseTimeout is null or @CurrentTS>LeaseTimeout) order by Id asc if @@ROWCOUNT> 0 begin update QueuedImportJobs set LeaseTimeout = DATEADD(mi,5,@CurrentTS), LeaseTicket=newid() where Id=@RecordId select * from QueuedImportJobs where Id = @RecordId end commit tran RecordId is the PK and there is also an index on Status,LeaseTimeout. What I'm basically doing is select a record of which the lease happens to be expired, while simultaneously updating the lease time with 5 minutes and setting a new lease ticket. So the problem is that I'm getting deadlocks when I run this code in parallel using a couple of threads. I've debugged it up to the point where I found out that the update statement sometimes gets executing twice for the same record. Now, I was under the impression that the with (updlock) should prevent this (it also happens with xlock btw, not with tablockx). So it actually look like there is a RangeS-U and a RangeX-X lock on the same range of records, which ought to be impossible. So what am I missing? I'm thinking it might have something to do with the top 1 clause or that SQL Server does not know that where Id=@RecordId is actually in the locked range? Deadlock graph: Table schema (simplified):

  Read the article

• exit /B 0 does not work

  - by murxx

  I have the following problem: I have created a batch script which calls itself in there (for being able to write a log in parallel). In the script I start another process (like start startServer.bat) which starts up a java process and keeps opened up all the time. In my original script I wait 30 seconds, check if the process is running and do an: exit /B 0 Unfortunately that does not work, the window shows that the exit /B 0 is being evaluated, but the window still keeps open. When I close the window with the other process (meaning the "child" processes started up in my .bat) my script continues its run. So: scriptA.bat -> in there I call: start startServer.bat -> wait 30 seconds -> check is server is started -> exit /B 0 Process hangs up! What's very odd, if I wrap another script around, like: scriptB.bat -> call scriptA.bat -----> in there I call: start startServer.bat -----> wait 30 seconds -----> check if server is started -----> exit /B 0 -> scriptA.bat continues without any hangup! I also tried the same with exit 0 (without /B) also, same result! In the first case it hangs up, in the second case my window closes as expected... Has anyone of you ever had such a problem before and knows what's wrong here? Process hangs up!

  Read the article

• Recommendations for IPC between parent and child processes in .NET?

  - by Jeremy

  My .NET program needs to run an algorithm that makes heavy use of 3rd party libraries (32-bit), most of which are unmanaged code. I want to drive the CPU as hard as I can, so the code runs several threads in parallel to divide up the work. I find that running all these threads simultaneously results in temporary memory spikes, causing the process' virtual memory size to approach the 2 GB limit. This memory is released back pretty quickly, but occasionally if enough threads enter the wrong sections of code at once, the process crosses the "red line" and either the unmanaged code or the .NET code encounters an out of memory error. I can throttle back the number of threads but then my CPU usage is not as high as I would like. I am thinking of creating worker processes rather than worker threads to help avoid the out of memory errors, since doing so would give each thread of execution its own 2 GB of virtual address space (my box has lots of RAM). I am wondering what are the best/easiest methods to communicate the input and output between the processes in .NET? The file system is an obvious choice. I am used to shared memory, named pipes, and such from my UNIX background. Is there a Windows or .NET specific mechanism I should use?

  Read the article

• Execute a block of database querys

  - by Nightmare

  I have the following task to complete: In my program a have a block of database querys or questions. I want to execute these questions and wait for the result of all questions or catch an error if one question fails! My Question object looks like this (simplified): public class DbQuestion(String sql) { [...] } [...] //The answer is just a holder for custom data... public void SetAnswer(DbAnswer answer) { //Store the answer in the question and fire a event to the listeners this.OnAnswered(EventArgs.Empty); } [...] public void SetError() { //Signal an Error in this query! this.OnError(EventArgs.Empty); } So every question fired to the database has a listener that waits for the parsed result. Now I want to fire some questions asynchronous to the database (max. 5 or so) and fire an event with the data from all questions or an error if only one question throws one! Which is the best or a good way to accomplish this task? Can I really execute more then one question parallel and stop all my work when one question throws an error? I think I need some inspiration on this... Just a note: I´m working with .NET framework 2.0

  Read the article

• What's the proper approach for writing multi-path "story" flows?

  - by Basiclife

  Hi, I wonder if you can help me. I'm writing a game (2d) which allows players to take multiple routes, some of which branch/merge - perhaps even loop. Each section of the game will decide which section is loaded next. I'm calling each section an IStoryElement - And I'm wondering how best to link these elements up in a way that is easily changed/configured and at the same time, graphable I'm going to have an engine/factory assembly which will load the appropriate StoryElement(s) based on various config options. I initially planned to give each StoryElement a NextElement() As IStoryElement property and a Completed() event. When the vent fires, the engine reads the NextElement property to find the next StoryElement. The downside to this is that if I ever wanted to graph all the routes through the game, I would be unable to - I couldn't determine all possible targets for each StoryElement. I considered a couple of other solutions but they all feel a little clunky - eg Do I need an additional layer of abstraction? ie StoryElementPlayers or similar - Each one would be responsible for stringing together multiple StoryElement perhaps a Series and a ChoicePlayer with each responsible for graphing its own StoryElement - But this will just move the problem up a layer. In short, I need some way of emulating a simple but dynamic workflow (but I'd rather not actually use WWF). Is there a pattern for something this simple? All the ones I've managed to find relate to more advanced control flow (parallel processing, etc.)

  Read the article

• Framework or tool for "distributed unit testing"?

  - by user262646

  Is there any tool or framework able to make it easier to test distributed software written in Java? My system under test is a peer-to-peer software, and I'd like to perform testing using something like PNUnit, but with Java instead of .Net. The system under test is a framework I'm developing to build P2P applications. It uses JXTA as a lower subsystem, trying to hide some complexities of it. It's currently an academic project, so I'm pursuing simplicity at this moment. In my test, I want to demonstrate that a peer (running in its own process, possibly with multiple threads) can discover another one (running in another process or even another machine) and that they can exchange a few messages. I'm not using mocks nor stubs because I need to see both sides working simultaneously. I realize that some kind of coordination mechanism is needed, and PNUnit seems to be able to do that. I've bumped into some initiatives like Pisces, which "aims to provide a distributed testing environment that extends JUnit, giving the developer/tester an ability to run remote JUnits and create complex test suites that are composed of several remote JUnit tests running in parallel or serially", but this project and a few others I have found seem to be long dead.

  Read the article

• The correct usage of nested #pragma omp for directives

  - by GoldenLee

  The following code runs like a charm before OpenMP parallelization was applied. In fact, the following code was in a state of endless loop! I'm sure that's result from my incorrect use to the OpenMP directives. Would you please show me the correct way? Thank you very much. #pragma omp parallel for for (int nY = nYTop; nY <= nYBottom; nY++) { for (int nX = nXLeft; nX <= nXRight; nX++) { // Use look-up table for performance dLon = theApp.m_LonLatLUT.LonGrid()[nY][nX] + m_FavoriteSVISSRParams.m_dNadirLon; dLat = theApp.m_LonLatLUT.LatGrid()[nY][nX]; // If you don't want to use longitude/latitude look-up table, uncomment the following line //NOMGeoLocate.XYToGEO(dLon, dLat, nX, nY); if (dLon > 180 || dLat > 180) { continue; } if (Navigation.GeoToXY(dX, dY, dLon, dLat, 0) > 0) { continue; } // Skip void data scanline dY = dY - nScanlineOffset; // Compute coefficients as well as its four neighboring points' values nX1 = int(dX); nX2 = nX1 + 1; nY1 = int(dY); nY2 = nY1 + 1; dCx = dX - nX1; dCy = dY - nY1; dP1 = pIRChannelData->operator [](nY1)[nX1]; dP2 = pIRChannelData->operator [](nY1)[nX2]; dP3 = pIRChannelData->operator [](nY2)[nX1]; dP4 = pIRChannelData->operator [](nY2)[nX2]; // Bilinear interpolation usNomDataBlock[nY][nX] = (unsigned short)BilinearInterpolation(dCx, dCy, dP1, dP2, dP3, dP4); } }

  Read the article

• How expensive is a context switch? Is it better to implement a manual task switch than to rely on OS

  - by Vilx-

  The title says it all. Imagine I have two (three, four, whatever) tasks that have to run in parallel. Now, the easy way to do this would be to create separate threads and forget about it. But on a plain old single-core CPU that would mean a lot of context switching - and we all know that context switching is big, bad, slow, and generally simply Evil. It should be avoided, right? On that note, if I'm writing the software from ground up anyway, I could go the extra mile and implement my own task-switching. Split each task in parts, save the state inbetween, and then switch among them within a single thread. Or, if I detect that there are multiple CPU cores, I could just give each task to a separate thread and all would be well. The second solution does have the advantage of adapting to the number of available CPU cores, but will the manual task-switch really be faster than the one in the OS core? Especially if I'm trying to make the whole thing generic with a TaskManager and an ITask, etc?

  Read the article

• Releasing Autopool crashes on iOS 4.0 (and only on 4.0)

  - by samsam

  Hi there. I'm wondering what could cause this. I have several methods in my code that i call using performSelectorInBackground. Within each of these methods i have an Autoreleasepool that is being alloced/initialized at the beginning and released at the end of the method. this perfectly works on iOS 3.1.3 / 3.2 / 4.2 / 4.2.1 but it fataly crashes on iOS 4.0 with a EXC_BAD_ACCESS Exception that happens after calling [myPool release]. After I noticed this strange behaviour I was thinking about rewriting portions of my code and to make my app "less parallel" in case that the client os is 4.0. After I did that, the next point where the app crashed was within the ReachabilityCallback-Method from Apples Reachability "Framework". well, now I'm not quite sure what to do. The things i do within my threaded methods is pretty simple xml parsing (no cocoa calls or stuff that would affect the UI). After each method finishes it posts a notification which the coordinating-thread listens to and once all the parallelized methods have finished, the coordinating thread calls viewcontrollers etc... I have absolutely no clue what could cause this weird behaviour. Especially because Apples Code fails as well. any help is greatly appreciated! thanks, sam

  Read the article

< Previous Page | 176 177 178 179 180 181 182 183 184 185 186 187  | Next Page >