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• Problem: Vectorizing Code with Intel Visual FORTRAN for X64

  - by user313209

  I'm compiling my fortran90 code using Intel Visual FORTRAN on Windows Server 2003 Enterprise X64 Edition. When I compile the code for 32 bit structure and using automatic and manual vectorizing options. The code will be compiled, vectorized. And when I run it on 8 core system the compiled code uses 70% of CPU that shows me that vectorizing is working. But when I compile the code with 64 Bit compiler, it says that the code is vectorized but when I run it it only shows CPU usage of about 12% that is full usage for one core out of 8, so it means that while the compiler says that code is vectorized, vectorization is not working. And it's strange for me because it's on a X64 Edition Windows and I was expecting to see the reverse result. I thought that it should be better to run a code that is compiled for 64 Bit architecture on a 64 bit windows. Anyone have any idea why the compiled code is not able to use the full power of multiple cores for 64 Bit Compiled version? Thanks in advance for your responses.

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• High performance text file parsing in .net

  - by diamandiev

  Here is the situation: I am making a small prog to parse server log files. I tested it with a log file with several thousand requests (between 10000 - 20000 don't know exactly) What i have to do is to load the log text files into memory so that i can query them. This is taking the most resources. The methods that take the most cpu time are those (worst culprits first): string.split - splits the line values into a array of values string.contains - checking if the user agent contains a specific agent string. (determine browser ID) string.tolower - various purposes streamreader.readline - to read the log file line by line. string.startswith - determine if line is a column definition line or a line with values there were some others that i was able to replace. For example the dictionary getter was taking lots of resources too. Which i had not expected since its a dictionary and should have its keys indexed. I replaced it with a multidimensional array and saved some cpu time. Now i am running on a fast dual core and the total time it takes to load the file i mentioned is about 1 sec. Now this is really bad. Imagine a site that has tens of thousands of visits a day. It's going to take minutes to load the log file. So what are my alternatives? If any, cause i think this is just a .net limitation and i can't do much about it.

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• Google App Engine - Caching generated HTML

  - by Alexander

  I have written a Google App Engine application that programatically generates a bunch of HTML code that is really the same output for each user who logs into my system, and I know that this is going to be in-efficient when the code goes into production. So, I am trying to figure out the best way to cache the generated pages. The most probable option is to generate the pages and write them into the database, and then check the time of the database put operation for a given page against the time that the code was last updated. Then, if the code is newer than the last put to the database (for a particular HTML request), new HTML will be generated and served, and cached to the database. If the code is older than the last put to the database, then I will just get the HTML direct from the database and serve it (therefore avoiding all the CPU wastage of generating the HTML). I am not only looking to minimize load times, but to minimize CPU usage. However, one issue that I am having is that I can't figure out how to programatically check when the version of code uploaded to the app engine was updated. I am open to any suggestions on this approach, or other approaches for caching generated html. Note that while memcache could help in this situation, I believe that it is not the final solution since I really only need to re-generate html when the code is updated (as opposed to every time the memcache expires). Kind Regards, and thank you in advance for any suggestions you may be able to offer. -Alex

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• What does flushing thread local memory to global memory mean?

  - by Jack Griffith

  Hi, I am aware that the purpose of volatile variables in Java is that writes to such variables are immediately visible to other threads. I am also aware that one of the effects of a synchronized block is to flush thread-local memory to global memory. I have never fully understood the references to 'thread-local' memory in this context. I understand that data which only exists on the stack is thread-local, but when talking about objects on the heap my understanding becomes hazy. I was hoping that to get comments on the following points: When executing on a machine with multiple processors, does flushing thread-local memory simply refer to the flushing of the CPU cache into RAM? When executing on a uniprocessor machine, does this mean anything at all? If it is possible for the heap to have the same variable at two different memory locations (each accessed by a different thread), under what circumstances would this arise? What implications does this have to garbage collection? How aggressively do VMs do this kind of thing? Overall, I think am trying to understand whether thread-local means memory that is physically accessible by only one CPU or if there is logical thread-local heap partitioning done by the VM? Any links to presentations or documentation would be immensely helpful. I have spent time researching this, and although I have found lots of nice literature, I haven't been able to satisfy my curiosity regarding the different situations & definitions of thread-local memory. Thanks very much.

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• Java runs out of memory, even though I give it plenty!

  - by spitzanator

  Hey, folks. So, I'm running a java server (specifically Winstone: http://winstone.sourceforge.net/ ) Like this: java -server -Xmx12288M -jar /usr/share/java/winstone-0.9.10.jar --useSavedSessions=false --webappsDir=/var/servlets --commonLibFolder=/usr/share/java This has worked fine in the past, but now it needs to load a bunch more stuff into memory than it has before. The odd part is that, according to 'top', it has 15.0g of VIRT(ual memory) and it's RES(ident set) is 8.4g. Once it hits 8.4g, the CPU hangs at 100% (even though it's loading from disk), and eventually, I get Java's OutOfMemoryError. Presumably, the CPU hanging at 100% is Java doing garbage collection. So, my question is, what gives? I gave it 12 gigs of memory! And it's only using 8.2 gigs before it throws in the towel. What am I doing wrong? Oh, and I'm using java version "1.6.0_07" Java(TM) SE Runtime Environment (build 1.6.0_07-b06) Java HotSpot(TM) 64-Bit Server VM (build 10.0-b23, mixed mode) on Linux. Thanks, Matt

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• Thoughts on GoGrid vs EC2

  - by Jason

  I am currently hosting my SaaS application at GoGrid (Microsoft stack). Here's what I have: Database Server - physical box, 12 GB RAM, 2 X Quad Core CPU (2.13 GHz Xeon E5506) 2 Web / App servers - cloud servers, 2 GB RAM, 2 VCPUs 300 GB monthly bandwidth I am paying around $900 / month for this. My web / app servers are busting at the seams and need to be upgraded to 4 GB of RAM. I also need a firewall, and GoGrid just added this service for an additional $200. After the upgrade, I will be paying around $1,400. I started looking at Amazon EC2, specifically this config: Database server - "High Memory Double Extra Large Instance" - 34 GB RAM, 13 EC2 compute units 2 Web / App servers - "Large Instance" - 7.5 GB RAM, 4 EC2 compute units If I go with 1 year reserved instances, my upfront cost would be $4,500 and my monthly would be $700. This comes to $1,075 / month when amortized. Amazon also includes a firewall for free. Here are my questions: Do any of you have experience running a database (especially SQL Server) on an EC2 instance? How did it perform compared to a dedicated machine? One of my major concerns is with disk I/O. Amazon's description of a compute unit is fairly vague. Any ideas on how the CPU performance on the database servers would compare? I am hoping that the Amazon solution will provide significantly better performance than my current or even improved GoGrid setup. Having a virtual database server would also be nice in terms of availability. Right now I would be in serious trouble if I had any hardware issues. Thanks for any insight...

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• Reading same file from multiple threads in C#

  - by Gustavo Rubio

  Hi. I was googling for some advise about this and I found some links. The most obvious was this one but in the end what im wondering is how well my code is implemented. I have basically two classes. One is the Converter and the other is ConverterThread I create an instance of this Converter class that has a property ThreadNumber that tells me how many threads should be run at the same time (this is read from user) since this application will be used on multi-cpu systems (physically, like 8 cpu) so it is suppossed that this will speed up the import The Converter instance reads a file that can range from 100mb to 800mb and each line of this file is a tab-delimitted value record that is imported to another destination like a database. The ConverterThread class simply runs inside the thread (new Thread(ConverterThread.StartThread)) and has event notification so when its work is done it can notify the Converter class and then I can sum up the progress for all these threads and notify the user (in the GUI for example) about how many of these records have been imported and how many bytes have been read. It seems, however that I'm having some trouble because I get random errors about the file not being able to be read or that the sum of the progress (percentage) went above 100% which is not possible and I think that happens because threads are not being well managed and probably the information returned by the event is malformed (since it "travels" from one thread to another) Do you have any advise on better practices of implementation of threads so I can accomplish this? Thanks in advance.

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• How to know if a device can be disabled or not?

  - by user326498

  I use the following code to enable/disable a device installed on my computer: SP_PROPCHANGE_PARAMS params; memset(&params, 0, sizeof(params)); devParams.cbSize = sizeof(devParams); params.ClassInstallHeader.cbSize = sizeof(params.ClassInstallHeader); params.ClassInstallHeader.InstallFunction = DIF_PROPERTYCHANGE; params.Scope = DICS_FLAG_GLOBAL; params.StateChange = DICS_DISABLE ; params.HwProfile = 0; // current profile if(!SetupDiSetClassInstallParams(m_hDev, &m_hDevInfo,&params.ClassInstallHeader,sizeof(SP_PROPCHANGE_PARAMS))) { dwErr = GetLastError(); return FALSE; } if(!SetupDiCallClassInstaller(DIF_PROPERTYCHANGE,m_hDev,&m_hDevInfo)) { dwErr = GetLastError(); return FALSE; } return TRUE; This code works perfectly only for those devices that can also be disabled by using Windows Device Manager, and won't work for some un-disabled devices such as my cpu device: Intel(R) Pentium(R) Dual CPU E2160 @ 1.80GHz. So the problem is how to determine if a device can be disabled or not programmatically? Is there any API to realize this goal? Thank you!

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• Parsing data with Clojure, interval problem.

  - by Andrea Di Persio

  Hello! I'm writing a little parser in clojure for learning purpose. basically is a TSV file parser that need to be put in a database, but I added a complication. The complication itself is that in the same file there are more intervals. The file look like this: ###andreadipersio 2010-03-19 16:10:00### USER COMM PID PPID %CPU %MEM TIME root launchd 1 0 0.0 0.0 2:46.97 root DirectoryService 11 1 0.0 0.2 0:34.59 root notifyd 12 1 0.0 0.0 0:20.83 root diskarbitrationd 13 1 0.0 0.0 0:02.84` .... ###andreadipersio 2010-03-19 16:20:00### USER COMM PID PPID %CPU %MEM TIME root launchd 1 0 0.0 0.0 2:46.97 root DirectoryService 11 1 0.0 0.2 0:34.59 root notifyd 12 1 0.0 0.0 0:20.83 root diskarbitrationd 13 1 0.0 0.0 0:02.84 I ended up with this code: (defn is-header? "Return true if a line is header" [line] (> (count (re-find #"^\#{3}" line)) 0)) (defn extract-fields "Return regex matches" [line pattern] (rest (re-find pattern line))) (defn process-lines [lines] (map process-line lines)) (defn process-line [line] (if (is-header? line) (extract-fields line header-pattern)) (extract-fields line data-pattern)) My idea is that in 'process-line' interval need to be merged with data so I have something like this: ('andreadipersio', '2010-03-19', '16:10:00', 'root', 'launchd', 1, 0, 0.0, 0.0, '2:46.97') for every row till the next interval, but I can't figure how to make this happen. I tried with something like this: (def process-line [line] (if is-header? line) (def header-data (extract-fields line header-pattern))) (cons header-data (extract-fields line data-pattern))) But this doesn't work as excepted. Any hints? Thanks!

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• Am I a discoverer of a bug in the WPF engine?

  - by bitbonk

  We have a MFC 8 application compiled with /CLR that contains a larger amount of Windows Forms UserControls wich again contain WPF user controls using ElementHost. Due to the architecture of our software we can not use HwndHost directly. We observed an extremely strange behavior here that we can not make any sense of: When the CPU load is very high during startup of the application and there are a lot live of ElementHost instances, the whole property engine completely stops working. For example animations that usually just work fine now never update the values of the bound properties, they just stay at some random value after startup. When I set a property that is not bound to anything the value is correctly stored in the dependency property (calling the getter returns the new value) but the visual representation never reflects that. I set the background to red but the background color does not change. We tested this on a lot of different machines all running Windows XP SP2 and it is pretty reproducible. The funny thing here is, that there is in fact one situation where the bound properties actually pickup a new value from the animation and the visual gets updated based on the property values. It is when I resize the ElementHost or when I hide and reshow the parent native control. As soon as I do this, properties that are bound to an animation pickup a new value and the visuals rerender based on the new property values - but just once - if I want to see another update I have to resize the ElementHost. Do you have any explanation of what could be happening here or how I could approach this problem to find it out? What can I do to debug this? Is there a way I can get more information about what WPF actually does or where WPF might have crashed? To me it currently seems like a bug in WPF itself since it only happens at high CPU load at startup.

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• Update SQL Server 2000 to SQL Server 2008: Benefits please?

  - by Ciaran Archer

  Hi there I'm looking for the benefits of upgrading from SQL Server 2000 to 2008. I was wondering: What database features can we leverage with 2008 that we can't now? What new TSQL features can we look forward to using? What performance benefits can we expect to see? What else will make management go for it? And the converse: What problems can we expect to encounter? What other problems have people found when migrating? Why fix something that isn't (technically) broken? We work in a Java shop, so any .NET / CLR stuff won't rock our world. We also use Eclipse as our main development so any integration with Visual Studio won't be a plus. We do use SQL Server Management Studio however. Some background: Our main database machine is a 32bit Dell Intel Xeon MP CPU 2.0GHz, 40MB of RAM with Physical Address Extension running Windows Server 2003 Enterprise Edition. We will not be changing our hardware. Our databases in total are under a TB with some having more than 200 tables. But they are busy and during busy times we see 60-80% CPU utilisation. Apart form the fact that SQL Server 2000 is coming close to end of life, why should we upgrade? Any and all contributions are appreciated!

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• AnyCPU/x86/x64 for C# application and it's C++/CLI dependency

  - by Soonts

  I'm Windows developer, I'm using Microsoft visual studio 2008 SP1. My developer machine is 64 bit. The software I'm currently working on is managed .exe written in C#. Unfortunately, I was unable to solve the whole problem solely in C#. That's why I also developed a small managed DLL in C++/CLI. Both projects are in the same solution. My C# .exe build target is "Any CPU". When my C++ DLL build target is "x86", the DLL is not loaded. As far as I understood when I googled, the reason is C++/CLI language, unlike other .NET languages, compiles to the native code, not managed code. I switched the C++ DLL build target to x64, and everything works now. However, AFAIK everything will stop working as soon as my client will install my product on a 32-bit OS. I have to support Windows Vista and 7, both 32 and 64 bit versions of each of them. I don't want to fall back to 32 bits. That 250 lines of C++ code in my DLL is only 2% of my codebase. And that DLL is only used in several places, so in the typical usage scenario it's not even loaded. My DLL implements two COM objects with ATL, so I can't use "/clr:safe" project setting. Is there way to configure the solution and the projects so that C# project builds "Any CPU" version, the C++ project builds both 32 bit and 64 bit versions, then in the runtime when the managed .EXE is starting up, it uses either 32-bit DLL or 64-bit DLL depending on the OS? Or maybe there's some better solution I'm not aware of? Thanks in advance!

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• Custom Controls Properties - C# , Forms - :(

  - by user353600

  Hi I m adding custom control to my flowlayoutpanel , its a sort of forex data , refresh every second , so on each timer tick , i m adding a control , changing controls button text , then adding it to flowlayout panel , i m doing it at each 100ms timer tick , it takeing tooo much CPU , here is my custom Control . public partial class UserControl1 : UserControl { public UserControl1() { InitializeComponent(); } private void UserControl1_Load(object sender, EventArgs e) { } public void displaydata(string name , string back3price , string back3 , string back2price , string back2 , string back1price , string back1 , string lay3price , string lay3 , string lay2price , string lay2 , string lay1price , string lay1 ) { lblrunnerName.Text = name.ToString(); btnback3.Text = back3.ToString() + "\n" + back3price.ToString(); btnback2.Text = back2.ToString() + "\n" + back2price.ToString(); btnback1.Text = back1.ToString() + "\n" + back1price.ToString(); btnlay1.Text = lay1.ToString() + "\n" + lay1price.ToString(); btnlay2.Text = lay2.ToString() + "\n" + lay2price.ToString(); btnlay3.Text = lay3.ToString() + "\n" + lay3price.ToString(); } and here is how i m adding control; private void timer1_Tick(object sender, EventArgs e) { localhost.marketData[] md; md = ser.getM1(); flowLayoutPanel1.Controls.Clear(); foreach (localhost.marketData item in md) { UserControl1 ur = new UserControl1(); ur.Name = item.runnerName + item.runnerID; ur.displaydata(item.runnerName, item.back3price, item.back3, item.back2price, item.back2, item.back1price, item.back1, item.lay3price, item.lay3, item.lay2price, item.lay2, item.lay1price, item.lay1); flowLayoutPanel1.SuspendLayout(); flowLayoutPanel1.Controls.Add(ur); flowLayoutPanel1.ResumeLayout(); } } now its happing on 10 times on each send , taking 60% of my Core2Duo cpu . is there any other way , i can just add contols first time , and then change the text of cutom controls buttons on runtime on each refresh or timer tick i m using c# .Net

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• Is there a reason why SSIS significantly slows down after a few minutes?

  - by Mark

  I'm running a fairly substantial SSIS package against SQL 2008 - and I'm getting the same results both in my dev environment (Win7-x64 + SQL-x64-Developer) and the production environment (Server 2008 x64 + SQL Std x64). The symptom is that initial data loading screams at between 50K - 500K records per second, but after a few minutes the speed drops off dramatically and eventually crawls embarrasingly slowly. The database is in Simple recovery model, the target tables are empty, and all of the prerequisites for minimally logged bulk inserts are being met. The data flow is a simple load from a RAW input file to a schema-matched table (i.e. no complex transforms of data, no sorting, no lookups, no SCDs, etc.) The problem has the following qualities and resiliences: Problem persists no matter what the target table is. RAM usage is lowish (45%) - there's plenty of spare RAM available for SSIS buffers or SQL Server to use. Perfmon shows buffers are not spooling, disk response times are normal, disk availability is high. CPU usage is low (hovers around 25% shared between sqlserver.exe and DtsDebugHost.exe) Disk activity primarily on TempDB.mdf, but I/O is very low (< 600 Kb/s) OLE DB destination and SQL Server Destination both exhibit this problem. To sum it up, I expect either disk, CPU or RAM to be exhausted before the package slows down, but instead its as if the SSIS package is taking an afternoon nap. SQL server remains responsive to other queries, and I can't find any performance counters or logged events that betray the cause of the problem. I'll gratefully reward any reasonable answers / suggestions.

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• Boost threading/mutexs, why does this work?

  - by Flamewires

  Code: #include <iostream> #include "stdafx.h" #include <boost/thread.hpp> #include <boost/thread/mutex.hpp> using namespace std; boost::mutex mut; double results[10]; void doubler(int x) { //boost::mutex::scoped_lock lck(mut); results[x] = x*2; } int _tmain(int argc, _TCHAR* argv[]) { boost::thread_group thds; for (int x = 10; x>0; x--) { boost::thread *Thread = new boost::thread(&doubler, x); thds.add_thread(Thread); } thds.join_all(); for (int x = 0; x<10; x++) { cout << results[x] << endl; } return 0; } Output: 0 2 4 6 8 10 12 14 16 18 Press any key to continue . . . So...my question is why does this work(as far as i can tell, i ran it about 20 times), producing the above output, even with the locking commented out? I thought the general idea was: in each thread: calculate 2*x copy results to CPU register(s) store calculation in correct part of array copy results back to main(shared) memory I would think that under all but perfect conditions this would result in some part of the results array having 0 values. Is it only copying the required double of the array to a cpu register? Or is it just too short of a calculation to get preempted before it writes the result back to ram? Thanks.

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• What's the most trivial function that would benfit from being computed on a GPU?

  - by hanDerPeder

  Hi. I'm just starting out learning OpenCL. I'm trying to get a feel for what performance gains to expect when moving functions/algorithms to the GPU. The most basic kernel given in most tutorials is a kernel that takes two arrays of numbers and sums the value at the corresponding indexes and adds them to a third array, like so: __kernel void add(__global float *a, __global float *b, __global float *answer) { int gid = get_global_id(0); answer[gid] = a[gid] + b[gid]; } __kernel void sub(__global float* n, __global float* answer) { int gid = get_global_id(0); answer[gid] = n[gid] - 2; } __kernel void ranksort(__global const float *a, __global float *answer) { int gid = get_global_id(0); int gSize = get_global_size(0); int x = 0; for(int i = 0; i < gSize; i++){ if(a[gid] > a[i]) x++; } answer[x] = a[gid]; } I am assuming that you could never justify computing this on the GPU, the memory transfer would out weight the time it would take computing this on the CPU by magnitudes (I might be wrong about this, hence this question). What I am wondering is what would be the most trivial example where you would expect significant speedup when using a OpenCL kernel instead of the CPU?

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• What OpenGL functions are not GPU accelerated?

  - by Xavier Ho

  I was shocked when I read this (from the OpenGL wiki): glTranslate, glRotate, glScale Are these hardware accelerated? No, there are no known GPUs that execute this. The driver computes the matrix on the CPU and uploads it to the GPU. All the other matrix operations are done on the CPU as well : glPushMatrix, glPopMatrix, glLoadIdentity, glFrustum, glOrtho. This is the reason why these functions are considered deprecated in GL 3.0. You should have your own math library, build your own matrix, upload your matrix to the shader. For a very, very long time I thought most of the OpenGL functions use the GPU to do computation. I'm not sure if this is a common misconception, but after a while of thinking, this makes sense. Old OpenGL functions (2.x and older) are really not suitable for real-world applications, due to too many state switches. This makes me realise that, possibly, many OpenGL functions do not use the GPU at all. So, the question is: Which OpenGL function calls don't use the GPU? I believe knowing the answer to the above question would help me become a better programmer with OpenGL. Please do share some of your insights.

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• 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?

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• What about parallelism across network using multiple PCs?

  - by MainMa

  Parallel computing is used more and more, and new framework features and shortcuts make it easier to use (for example Parallel extensions which are directly available in .NET 4). Now what about the parallelism across network? I mean, an abstraction of everything related to communications, creation of processes on remote machines, etc. Something like, in C#: NetworkParallel.ForEach(myEnumerable, () => { // Computing and/or access to web ressource or local network database here }); I understand that it is very different from the multi-core parallelism. The two most obvious differences would probably be: The fact that such parallel task will be limited to computing, without being able for example to use files stored locally (but why not a database?), or even to use local variables, because it would be rather two distinct applications than two threads of the same application, The very specific implementation, requiring not just a separate thread (which is quite easy), but spanning a process on different machines, then communicating with them over local network. Despite those differences, such parallelism is quite possible, even without speaking about distributed architecture. Do you think it will be implemented in a few years? Do you agree that it enables developers to easily develop extremely powerfull stuff with much less pain? Example: Think about a business application which extracts data from the database, transforms it, and displays statistics. Let's say this application takes ten seconds to load data, twenty seconds to transform data and ten seconds to build charts on a single machine in a company, using all the CPU, whereas ten other machines are used at 5% of CPU most of the time. In a such case, every action may be done in parallel, resulting in probably six to ten seconds for overall process instead of forty.

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• Which OpenGL functions are not GPU-accelerated?

  - by Xavier Ho

  I was shocked when I read this (from the OpenGL wiki): glTranslate, glRotate, glScale Are these hardware accelerated? No, there are no known GPUs that execute this. The driver computes the matrix on the CPU and uploads it to the GPU. All the other matrix operations are done on the CPU as well : glPushMatrix, glPopMatrix, glLoadIdentity, glFrustum, glOrtho. This is the reason why these functions are considered deprecated in GL 3.0. You should have your own math library, build your own matrix, upload your matrix to the shader. For a very, very long time I thought most of the OpenGL functions use the GPU to do computation. I'm not sure if this is a common misconception, but after a while of thinking, this makes sense. Old OpenGL functions (2.x and older) are really not suitable for real-world applications, due to too many state switches. This makes me realise that, possibly, many OpenGL functions do not use the GPU at all. So, the question is: Which OpenGL function calls don't use the GPU? I believe knowing the answer to the above question would help me become a better programmer with OpenGL. Please do share some of your insights.

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• How to speed up drawing of scaled image? Audio playback chokes during window resize.

  - by Paperflyer

  I am writing an audio player for OSX. One view is a custom view that displays a waveform. The waveform is stored as a instance variable of type NSImage with an NSBitmapImageRep. The view also displays a progress indicator (a thick red line). Therefore, it is updated/redrawn every 30 milliseconds. Since it takes a rather long time to recalculate the image, I do that in a background thread after every window resize and update the displayed image once the new image is ready. In the meantime, the original image is scaled to fit the view like this: // The drawing rectangle is slightly smaller than the view, defined by // the two margins. NSRect drawingRect; drawingRect.origin = NSMakePoint(sideEdgeMarginWidth, topEdgeMarginHeight); drawingRect.size = NSMakeSize([self bounds].size.width-2*sideEdgeMarginWidth, [self bounds].size.height-2*topEdgeMarginHeight); [waveform drawInRect:drawingRect fromRect:NSZeroRect operation:NSCompositeSourceOver fraction:1]; The view makes up the biggest part of the window. During live resize, audio starts choking. Selecting the "big" graphic card on my Macbook Pro makes it less bad, but not by much. CPU utilization is somewhere around 20-40% during live resizes. Instruments suggests that rescaling/redrawing of the image is the problem. Once I stop resizing the window, CPU utilization goes down and audio stops glitching. I already tried to disable image interpolation to speed up the drawing like this: [[NSGraphicsContext currentContext] setImageInterpolation:NSImageInterpolationNone]; That helps, but audio still chokes during live resizes. Do you have an idea how to improve this? The main thing is to prevent the audio from choking.

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• Java: GatheringByteChannel advantages?

  - by Jason S

  I'm wondering when the GatheringByteChannel's write methods (taking in an array of ByteBuffers) have advantages over the "regular" WritableByteChannel write methods. I tried a test where I could use the regular vs. the gathering write method on a FileChannel, with approx 400KB/sec total in ByteBuffers of between 23-27 bytes in length in both cases. Gathering writes used an array of 64. The regular method used up approx 12% of my CPU, and the gathering method used up approx 16% of my CPU (worse than the regular method!) This tells me it's NOT useful to use gathering writes on a FileChannel around this range of operating parameters. Why would this be the case, and when would you ever use GatheringByteChannel? (on network I/O?) Relevant differences here: public void log(Queue<Packet> packets) throws IOException { if (this.gather) { int Nbuf = 64; ByteBuffer[] bbufs = new ByteBuffer[Nbuf]; int i = 0; Packet p; while ((p = packets.poll()) != null) { bbufs[i++] = p.getBuffer(); if (i == Nbuf) { this.fc.write(bbufs); i = 0; } } if (i > 0) { this.fc.write(bbufs, 0, i); } } else { Packet p; while ((p = packets.poll()) != null) { this.fc.write(p.getBuffer()); } } }

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• android service using SystemClock.elapsedRealTime() instead of SystemClock.uptimeMillis() works in emulator but not in samsung captivate ?

  - by Aleadam

  First question here in stackoverflow :) I'm running a little android 2.2 app to log cpu frequency usage. It is set up as a service that will write the data every 10 seconds using a new thread. The code for that part is very basic (see below). It works fine, except that it would not keep track of time while the phone is asleep (which, I know, is the expected behavior). Thus, I changed the code to use SystemClock.elapsedRealTime() instead. Problem is, in emulator both commands are equivalent, but in the phone the app will start the thread but it will never execute the mHandler.postAtTime command. Any advice regarding why this is happening or how to overcome the issue is greatly appreciated. PS: stopLog() is not being called. That's not the problem. mUpdateTimeTask = new Runnable() { public void run() { long millis = SystemClock.uptimeMillis() - mStartTime; int seconds = (int) (millis / 1000); int minutes = seconds / 60; seconds = seconds % 60; String freq = readCPU (); if (freq == null) Toast.makeText(CPU_log_Service.this, "CPU frequency is unreadable.\nPlease make sure the file has read rights.", Toast.LENGTH_LONG).show(); String str = new String ((minutes*60 + seconds) + ", " + freq + "\n"); if (!writeLog (str)) stopLog(); mHandler.postAtTime(this, mStartTime + (((minutes * 60) + seconds + 10) * 1000)); }}; mStartTime = SystemClock.uptimeMillis(); mHandler.removeCallbacks(mUpdateTimeTask); mHandler.postDelayed(mUpdateTimeTask, 100);

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• Retrieving values from a table in HTML using jQuery?

  - by Mo

  Hi i was just wondering whats the best way to retrieve the following labels and values from this HTMl code using jquery and storing them in to a array or hash map of some sort where i have for e.g "DataSet:" : "prod" or ["Dataset", "Prod"]? <table id="metric_summary"> <tbody> <tr class="editable_metrics"> <td><label>DataSet:</label></td> <td><input name="DataSet" value="prod"></td> </tr> <tr class="editable_metrics"> <td><label>HostGroup:</label></td> <td><input name="HostGroup" value="MONITOR-PORTAL-IAD"></td> </tr> <tr class="editable_metrics"> <td><label>Host:</label></td> <td><input name="Host" value="ALL"></td> </tr> <tr class="editable_metrics"> <td><label>Class:</label></td> <td><input name="Class" value="CPU"></td> </tr> <tr class="editable_metrics"> <td><label>Object:</label></td> <td><input name="Object" value="cpu"></td> </tr> <tr class="editable_metrics"> <td><label>Metric:</label></td> <td><input name="Metric" value="CapacityCPUUtilization"></td> </tr> thanks

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• Database tables with dynamic information

  - by Tim Fennis

  I've googled this and found that it's almost impossible to create a database with dynamic collumns. I'll explain my problem first. I am making a webshop for a customer. It has multiple computer products for sale. CPU's HDD's RAM ect. All these products have different properties, a CPU has an FSB, RAM has a CAS latency. But this is very inconvenient because my orders table needs foreign keys to different tables which is impossible. An other option is to store all the product specific information in a varchar or blob field and let PHP figure it out. The problem with this solution is that the website needs a PC builder. A step-by-step guide to building your PC. So for instance if a customer decides he wants a new "i7 920" or whatever i want to be able to sellect all motherboards for socket 1366, which is impossible because all the data is stored in one field. I know it's possible to select all motherboards form the DB and let PHP figure out which ones are for socket 1366 but i was wondering, is there a better solution?

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