Search Results

Search found 15939 results on 638 pages for 'low memory'.

Page 469/638 | < Previous Page | 465 466 467 468 469 470 471 472 473 474 475 476  | Next Page >

  • Resizing JPEG image during decoding

    - by Thomas
    I'm working on a program that creates thumbnails of JPEG images on the fly. Now I was thinking: since a JPEG image is built from 8x8-pixel blocks (Wikipedia has a great explanation), would it be possible to skip part of the decoding? Let's say that my thumbnails are at least 8 times smaller than the original image. We could then map each 8x8 block in the input file to 1 pixel in the decoding output, by including only the constant term of the discrete cosine transform. Most of the image data can be discarded right away, and need not be processed. Moreover, the memory usage is reduced by a factor of 64. I don't want to implement this from scratch; that'll easily take a week. Is there any code out there that can do this? If not, is this because this approach isn't worthwhile, or simply because nobody has thought of it yet?

    Read the article

  • MVVM Good Design. DataSet or a RowViewModel

    - by LnDCobra
    I have just started learning MVVM and having a dilemna. If I have a a main ViewModel and inside this model I have a number of datasets. Now should I be creating a new ViewModel for each row inside the dataset? Or expose the DataSet itself as a DependencyProperty? For now the dataset has about 20 rows inside it, and the thought of iterating through each row to create a ViewModel binding to each row.... might not be the best option for performance reasons and memory reasons in the future, like when there are 1000+ rows. Should I still go ahead and create a RowViewModel and iterate through the dataset? And have an ObservableCollection of it or just expose the dataset? Any help would be greatly appreciated.

    Read the article

  • Sparse matrices / arrays in Java

    - by DanM
    I'm working on a project, written in Java, which requires that I build a very large 2-D sparse array. Very sparse, if that makes a difference. Anyway: the most crucial aspect for this application is efficency in terms of time (assume loads of memory, though not nearly so unlimited as to allow me to use a standard 2-D array -- the key range is in the billions in both dimensions). Out of the kajillion cells in the array, there will be several hundred thousand cells which contain an object. I need to be able to modify cell contents VERY quickly. Anyway: Does anyone know a particularly good library for this purpose? It would have to be Berkeley, LGPL or similar license (no GPL, as the product can't be entirely open-sourced). Or if there's just a very simple way to make a homebrew sparse array object, that'd be fine too. I'm considering MTJ, but haven't heard any opinions on its quality. Thanks!! -Dan

    Read the article

  • Studying MySQL, SQLite source code to learn about RDBMS implementation

    - by Yang
    I know implementing database is a huge topic, but I want to have a basic understanding of how database systems work (e.g. memory management, binary tree, transaction, sql parsing, multi-threading, partitions, etc) by investigating the source code of the database. Since there are a few already proven very robust open source databases like mysql, sqlite and so on. However, the code are very complicated and I have no clue where to start. Also I find that the old school database textbooks are only explaining the theory, not the implementation details. Can anyone suggest how I should get started and if there are any books that emphasis on the technology and techniques of building dbms used in modern database industry?

    Read the article

  • XSL Template outputting massive chunk of text, rather than HTML. But only on one section

    - by Throlkim
    I'm having a slightly odd situation with an XSL template. Most of it outputs fine, but a certain for-each loop is causing me problems. Here's the XML: <area> <feature type="Hall"> <Heading><![CDATA[Hall]]></Heading> <Para><![CDATA[Communal gardens, pathway leading to PVCu double glazed communal front door to]]></Para> </feature> <feature type="Entrance Hall"> <Heading><![CDATA[Communal Entrance Hall]]></Heading> <Para><![CDATA[Plain ceiling, centre light fitting, fire door through to inner hallway, wood and glazed panelled front door to]]></Para> </feature> <feature type="Inner Hall"> <Heading><![CDATA[Inner Hall]]></Heading> <Para><![CDATA[Plain ceiling with pendant light fitting and covings, security telephone, airing cupboard housing gas boiler serving domestic hot water and central heating, telephone point, storage cupboard housing gas and electric meters, wooden panelled doors off to all rooms.]]></Para> </feature> <feature type="Lounge (Reception)" width="3.05" length="4.57" units="metre"> <Heading><![CDATA[Lounge (Reception)]]></Heading> <Para><![CDATA[15' 6" x 10' 7" (4.72m x 3.23m) Window to the side and rear elevation, papered ceiling with pendant light fitting and covings, two double panelled radiators, power points, wall mounted security entry phone, TV aerial point.]]></Para> </feature> <feature type="Kitchen" width="3.05" length="3.66" units="metre"> <Heading><![CDATA[Kitchen]]></Heading> <Para><![CDATA[12' x 10' (3.66m x 3.05m) Double glazed window to the rear elevation, textured ceiling with strip lighting, range of base and wall units in Beech with brushed aluminium handles, co-ordinated working surfaces with inset stainless steel sink with mixer taps over, co-ordinated tiled splashbacks, gas and electric cooker points, large storage cupboard with shelving, power points.]]></Para> </feature> <feature type="Entrance Porch"> <Heading><![CDATA[Balcony]]></Heading> <Para><![CDATA[Views across the communal South facing garden, wrought iron balustrade.]]></Para> </feature> <feature type="Bedroom" width="3.35" length="3.96" units="metre"> <Heading><![CDATA[Bedroom One]]></Heading> <Para><![CDATA[13' 6" x 11' 5" (4.11m x 3.48m) Double glazed windows to the front and side elevations, papered ceiling with pendant light fittings and covings, single panelled radiator, power points, telephone point, security entry phone.]]></Para> </feature> <feature type="Bedroom" width="3.05" length="3.35" units="metre"> <Heading><![CDATA[Bedroom Two]]></Heading> <Para><![CDATA[11' 4" x 10' 1" (3.45m x 3.07m) Double glazed window to the front elevation, plain ceiling with centre light fitting and covings, power points.]]></Para> </feature> <feature type="bathroom"> <Heading><![CDATA[Bathroom]]></Heading> <Para><![CDATA[Obscure double glazed window to the rear elevation, textured ceiling with centre light fitting and extractor fan, suite in white comprising of low level WC, wall mounted wash hand basin and walk in shower housing 'Triton T80' electric shower, co-ordinated tiled splashbacks.]]></Para> </feature> </area> And here's the section of my template that processes it: <xsl:for-each select="area"> <li> <xsl:for-each select="feature"> <li> <h5> <xsl:value-of select="Heading"/> </h5> <xsl:value-of select="Para"/> </li> </xsl:for-each> </li> </xsl:for-each> And here's the output: Hall Communal gardens, pathway leading to PVCu double glazed communal front door to Communal Entrance Hall Plain ceiling, centre light fitting, fire door through to inner hallway, wood and glazed panelled front door to Inner Hall Plain ceiling with pendant light fitting and covings, security telephone, airing cupboard housing gas boiler serving domestic hot water and central heating, telephone point, storage cupboard housing gas and electric meters, wooden panelled doors off to all rooms. Lounge (Reception) 15' 6" x 10' 7" (4.72m x 3.23m) Window to the side and rear elevation, papered ceiling with pendant light fitting and covings, two double panelled radiators, power points, wall mounted security entry phone, TV aerial point. Kitchen 12' x 10' (3.66m x 3.05m) Double glazed window to the rear elevation, textured ceiling with strip lighting, range of base and wall units in Beech with brushed aluminium handles, co-ordinated working surfaces with inset stainless steel sink with mixer taps over, co-ordinated tiled splashbacks, gas and electric cooker points, large storage cupboard with shelving, power points. Balcony Views across the communal South facing garden, wrought iron balustrade. Bedroom One 13' 6" x 11' 5" (4.11m x 3.48m) Double glazed windows to the front and side elevations, papered ceiling with pendant light fittings and covings, single panelled radiator, power points, telephone point, security entry phone. Bedroom Two 11' 4" x 10' 1" (3.45m x 3.07m) Double glazed window to the front elevation, plain ceiling with centre light fitting and covings, power points. Bathroom Obscure double glazed window to the rear elevation, textured ceiling with centre light fitting and extractor fan, suite in white comprising of low level WC, wall mounted wash hand basin and walk in shower housing 'Triton T80' electric shower, co-ordinated tiled splashbacks. For reference, here's the entire XSLT: http://pastie.org/private/eq4gjvqoc1amg9ynyf6wzg The rest of it all outputs fine - what am I missing from the above section?

    Read the article

  • Best practice to display POI in iPhone's MapKit?

    - by iamj4de
    Assuming I have a database of POI with their respective coordinates (longitude & latitude). What would be the "standard" way to display the POI as annotations around the user's current location? To elaborate: Given a zoom level, I guess I have to search through the database for all POI whose distance to the current location < a certain threshold, then create annotations for them. Or is there any smarter way? If the user zooms in/out, moves the map... I will need to redo the whole thing again? It seems that MapKit has a mechanism to cache/reuse annotations. Should I create a lot of them right away and let MapKit decides what to render when the visible region changes? I guess this would make the transition smoother, but also consumes more memory. What is your experience with this? Thanks.

    Read the article

  • com.sun.management.OperatingSystemMXBean use in an OSGi bundle

    - by Paul Whelan
    I have some legacy code that was used to monitor my applications cpu,memory etc that I want to convert to a bundle. Now when i start this bundle its complaining Missing Constraint: Import-Package: com.sun.management; version="0.0.0" I had used the OperatingSystemMXBean to get access to stats on the JVM. My question is can I use this class inside an OSGI container and if so how? Or should I use some other way to monitor my application. I was making an RMI call to the application from a web frontend to get the nodes performance figures pre OSGi.

    Read the article

  • Best tools to monitor Tomcat

    - by Pier Luigi
    Hi all, I'm searching free tools for monitor tomcat (traffic, memory usage, threads, requests, CPU, logs,...). I'm currently using lambdaprobe on Tomcat 5.5.x, but it seems that is no more developed (or not? the site lambdaprobe.org is always down for me...). Has someone good experiences to share? In lambdaprobe there are some info available only if tomcat is instrumented with JMX. Well, JMX is something of strange and mysterious for me. Is a good solution in a production server? It's worth to spend my (little) time to learn it?

    Read the article

  • How can I walk through two files simultaneously in Perl?

    - by Alex Reynolds
    I have two text files that contain columnar data of the variety position-value, sorted by position. Here is an example of the first file (file A): 100 1 101 1 102 0 103 2 104 1 ... Here is an example of the second file (B): 20 0 21 0 ... 100 2 101 1 192 3 193 1 ... Instead of reading one of the two files into a hash table, which is prohibitive due to memory constraints, what I would like to do is walk through two files simultaneously, in a stepwise fashion. What this means is that I would like to stream through lines of either A or B and compare position values. If the two positions are equal, then I perform a calculation on the values associated with that position. Otherwise, if the positions are not equal, I move through lines of file A or file B until the positions are equal (when I again perform my calculation) or I reach EOF of both files. Is there a way to do this in Perl?

    Read the article

  • Core Data iPhone how often should I call [managedObjectContext save:&error] when doing 50k record in

    - by jamone
    I will be doing an occiasional import from XML into core data. I have around 50k entities that will be added. My question is how often should I call [managedObjectContext save:&error]. For every new entity added, or every x entities, or just at the end of the 50k import? I currently am calling it for each entity and tried only doing it for around every 10k and import speed went up drastically but after the first 30k it would crash with: *** Terminating app due to uncaught exception 'NSGenericException', reason: '*** Collection <NSCFSet: 0x13e760> was mutated while being enumerated.' Before I spend too much time trying to diagnose what is going on there I figured I'd check if its ok to not call save on every entity? Is the # of entities before calling save limited by the amount of memory those entities are using?

    Read the article

  • C++ wrapper for posix and linux specific functions

    - by Libzajc
    Hi Do you know about any good library wrapping posix and linux functions and structures ( eg. sockets or file descriptors ) into C++ classes? For example I'm thinking about a base FileDescriptor class and some inheriting classes ( unix sockets etc ) with methods like write, read or even some syscalls ( sendfile, splice ) - all throwing exceptions instead of setting errno. Or some shared memory class etc. I can't seem to find anything like that and by now I consider writing it myself, as I often have to write a C++ app for linux and either use C functions ( painful error checking ), or wrap them myself every time.

    Read the article

  • NameValueCollection vs Dictionary<string,string>

    - by frankadelic
    Any reason I should use Dictionary<string,string instead of NameValueCollection? (in C# / .NET Framework) Option 1, using NameValueCollection: //enter values: NameValueCollection nvc = new NameValueCollection() { {"key1", "value1"}, {"key2", "value2"}, {"key3", "value3"} }; // retrieve values: foreach(string key in nvc.AllKeys) { string value = nvc[key]; // do something } Option 2, using Dictionary<string,string... //enter values: Dictionary<string, string> dict = new Dictionary<string, string>() { {"key1", "value1"}, {"key2", "value2"}, {"key3", "value3"} }; // retrieve values: foreach (KeyValuePair<string, string> kvp in dict) { string key = kvp.Key; string val = kvp.Value; // do something } For these use cases, is there any advantage to use one versus the other? Any difference in performance, memory use, sort order, etc.?

    Read the article

  • Windows System Tray icons - controlling position

    - by Jamo
    I have a few old apps I've written (in Delphi) which for various reasons use a system tray icon. Most are using AppControls TacTrayIcon or some other similar component. Here's my question: How does one control the position of a tray icon? (i.e. where it is, say, relative to the system time -- 1st position/"slot", 2nd position/"slot", etc). I recall seeing a demo (C#, if memory serves) that allowed the user to "shift icon to the left" and "shift icon to the right", but don't recall how it was done. I'd like to allow the user to select what position they want to icon to appear in, for Windows 2000 - Windows 7. (I understand Windows 7 handles system tray stuff a little differently, but haven't tested that out yet). Thanks for any and all help.

    Read the article

  • ASP.NET Session expires in no time?

    - by Galilyou
    Weired problem! ASP.NET Session expires instantly. In my web.config I have this session settings: <sessionState mode="InProc" timeout="10000" /> AFAIK the timeout attribute's value is in minutes and can't be greater than 525,600 minutes (1 year). I don't understand what I am doing wrong here. Why is the session expiring. Is it a server memory issue? I don't think so, the server is pretty descent and it has only one site which isn't doing much after all. Ideas? EDIT: After setting the cookiless attribute to true, and while noticing the session id on the url, I can see that the session id CHANGING. I assume that this means the session is expiring. The IIS Settings are correct AFAIK (the enable session state checkbox is checked, and the value of the time is 20). A Picture is worth 100 words:

    Read the article

  • Passing a SAFEARRAY from C# to COM

    - by SlavaGu
    I use 3rd party COM to find faces in a picture. One of the methods has the following signature, from SDK: long FindMultipleFaces( IUnknown* pIDibImage, VARIANTARG* FacePositionArray ); Parameters: pIDibImage[in] - The image to search. FacePositionArray[out]- The array of FacePosition2 objects into which face information is placed. This array is in a safe array (VARIANT) of type VT_UNKNOWN. The size of the array dictates the maximum number of faces for which to search. which translates into the following C# method signature (from metadata): int FindMultipleFaces(object pIDibImage, ref object pIFacePositions); Being optimistic I call it the following way but get an exception that the memory is corrupt. The exception is thrown only when a face is present in the image. FacePosition2[] facePositions = new FacePosition2[10]; object positions = facePositions; int faceCount = FaceLocator.FindMultipleFaces(dibImage, ref positions); What's the right way to pass SAFEARRAY to unmanaged code?

    Read the article

  • Parsing Wiki XML Dumps ver0.4 just got tough

    - by syed
    Hello, I am trying to parse Wikipedia XML Dump using "Parse-MediaWikiDump-1.0.4" along with "Wikiprep.pl" script. I guess this script works fine with ver0.3 Wiki XML Dumps but not with the latest ver0.4 Dumps. I get the following error. Can't locate object method "page" via package "Parse::MediaWikiDump::Pages" at wikiprep.pl line 390. Also, under the "Parse-MediaWikiDump-1.0.4" documentation @ http://search.cpan.org/~triddle/Parse-MediaWikiDump-1.0.4/lib/Parse/MediaWikiDump/Pages.pm, I read "LIMITATIONS Version 0.4 This class was updated to support version 0.4 dump files from a MediaWiki instance but it does not currently support any of the new information available in those files." Any work arounds would help me get to the next level. Note: one may wonder why cannot we directly use SAX or STAX parser instead, wikipedia dump is a 25GB plus single file, stack/memory issues are obvious. Hence, the above perl script resolves this issue but currently I am stuck with this version problem.

    Read the article

  • SQL Server, temporary tables with truncate vs table variable with delete

    - by Richard
    I have a stored procedure inside which I create a temporary table that typically contains between 1 and 10 rows. This table is truncated and filled many times during the stored procedure. It is truncated as this is faster than delete. Do I get any performance increase by replacing this temporary table with a table variable when I suffer a penalty for using delete (truncate does not work on table variables) Whilst table variables are mainly in memory and are generally faster than temp tables do I loose any benefit by having to delete rather than truncate?

    Read the article

  • What's the best way to create a Windows Mobile application with multiple screens in C#

    - by Joseph Earl
    I am creating a Windows Mobile Application in C# and Visual Studio 2008. The application will have 5-6 main 'screens'. There will also be bar (/area) with information (e.g. a title, whether the app is busy, etc) above the screens, and a toolbar (or similar control) below the screens with 5-6 buttons (with images) to change the active screen (i.e. the screens will share the top bar and toolbar) What is the best way to implement this? Use multiple forms, and just include the toolbar and top-bar in each Use a single form and something like the Tab control (but customised) to contain the screens Something else? Keeping in mind a) memory usage and b) time to switch screens. Thanks in advance. Any links, pointers etc are much appreciated.

    Read the article

  • Thread and two dimensional array in objective C?

    - by mactonny
    Hey, guys, I am just starting to wrap my head around objective C and I am doing a little project on Iphone. And I just encountered a weird problem. I had to deal with images in my program so I have a lot local variables declared like temp[width][height]. If I am not using NSThread to perform image processing, it works all fine. However, if I use NSThread, it'll keep giving me EXC_BAD_ACCESS on whenever I try to access a 2-D array declared like temp[widht][height]. So I have to allocate memory from heap in order to have a 2-D array. That'll solve the problem but I still don't get it. My first thought would be stack over flow, but it worked all fine with one thread. I just don't get it.

    Read the article

  • Animation on the iPhone - use image sequence or rotation?

    - by user157733
    I am creating a basic animation for my iPhone app. I have a choice to make between 2 different types of animation. I can use this... NSArray *myImages = [NSArray arrayWithObjects: [UIImage imageNamed:@"myImage1.png"], [UIImage imageNamed:@"myImage2.png"], [UIImage imageNamed:@"myImage3.png"], [UIImage imageNamed:@"myImage4.gif"], nil]; UIImageView *myAnimatedView = [UIImageView alloc]; [myAnimatedView initWithFrame:[self bounds]]; myAnimatedView.animationImages = myImages; myAnimatedView.animationDuration = 0.25; [self addSubview:myAnimatedView]; [myAnimatedView release]; or something like this... [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:1.5]; // other animations goes here myImage.transform = CGAffineTransformMakeRotation(M_PI*0.5); // other animations goes here [UIView commitAnimations]; I have quite a few of these parts to animate so I want to choose an option which uses the least amount of memory and runds the quickest. Any advice would be great, thanks

    Read the article

  • What is the fastest cyclic synchronization in Java (ExecutorService vs. CyclicBarrier vs. X)?

    - by Alex Dunlop
    Which Java synchronization construct is likely to provide the best performance for a concurrent, iterative processing scenario with a fixed number of threads like the one outlined below? After experimenting on my own for a while (using ExecutorService and CyclicBarrier) and being somewhat surprised by the results, I would be grateful for some expert advice and maybe some new ideas. Existing questions here do not seem to focus primarily on performance, hence this new one. Thanks in advance! The core of the app is a simple iterative data processing algorithm, parallelized to the spread the computational load across 8 cores on a Mac Pro, running OS X 10.6 and Java 1.6.0_07. The data to be processed is split into 8 blocks and each block is fed to a Runnable to be executed by one of a fixed number of threads. Parallelizing the algorithm was fairly straightforward, and it functionally works as desired, but its performance is not yet what I think it could be. The app seems to spend a lot of time in system calls synchronizing, so after some profiling I wonder whether I selected the most appropriate synchronization mechanism(s). A key requirement of the algorithm is that it needs to proceed in stages, so the threads need to sync up at the end of each stage. The main thread prepares the work (very low overhead), passes it to the threads, lets them work on it, then proceeds when all threads are done, rearranges the work (again very low overhead) and repeats the cycle. The machine is dedicated to this task, Garbage Collection is minimized by using per-thread pools of pre-allocated items, and the number of threads can be fixed (no incoming requests or the like, just one thread per CPU core). V1 - ExecutorService My first implementation used an ExecutorService with 8 worker threads. The program creates 8 tasks holding the work and then lets them work on it, roughly like this: // create one thread per CPU executorService = Executors.newFixedThreadPool( 8 ); ... // now process data in cycles while( ...) { // package data into 8 work items ... // create one Callable task per work item ... // submit the Callables to the worker threads executorService.invokeAll( taskList ); } This works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as much as the processing algorithm would be expected to allow (some work items will finish faster than others, then idle). However, as the work items become smaller (and this is not really under the program's control), the user CPU load shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.8% 85% 1.30 64k 2.5% 77% 5.6 16k 4% 64% 22.5 4096 8% 56% 86 1024 13% 38% 227 256 17% 19% 420 64 19% 17% 948 16 19% 13% 1626 Legend: - block size = size of the work item (= computational steps) - system = system load, as shown in OS X Activity Monitor (red bar) - user = user load, as shown in OS X Activity Monitor (green bar) - cycles/sec = iterations through the main while loop, more is better The primary area of concern here is the high percentage of time spent in the system, which appears to be driven by thread synchronization calls. As expected, for smaller work items, ExecutorService.invokeAll() will require relatively more effort to sync up the threads versus the amount of work being performed in each thread. But since ExecutorService is more generic than it would need to be for this use case (it can queue tasks for threads if there are more tasks than cores), I though maybe there would be a leaner synchronization construct. V2 - CyclicBarrier The next implementation used a CyclicBarrier to sync up the threads before receiving work and after completing it, roughly as follows: main() { // create the barrier barrier = new CyclicBarrier( 8 + 1 ); // create Runable for thread, tell it about the barrier Runnable task = new WorkerThreadRunnable( barrier ); // start the threads for( int i = 0; i < 8; i++ ) { // create one thread per core new Thread( task ).start(); } while( ... ) { // tell threads about the work ... // N threads + this will call await(), then system proceeds barrier.await(); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; } public void run() { while( true ) { // wait for work barrier.await(); // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should), and for very large work items indeed all 8 CPUs become highly loaded, as before. However, as the work items become smaller, the load still shrinks dramatically: blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.7% 78% 6.1 16k 5.5% 52% 25 4096 9% 29% 64 1024 11% 15% 117 256 12% 8% 169 64 12% 6.5% 285 16 12% 6% 377 For large work items, synchronization is negligible and the performance is identical to V1. But unexpectedly, the results of the (highly specialized) CyclicBarrier seem MUCH WORSE than those for the (generic) ExecutorService: throughput (cycles/sec) is only about 1/4th of V1. A preliminary conclusion would be that even though this seems to be the advertised ideal use case for CyclicBarrier, it performs much worse than the generic ExecutorService. V3 - Wait/Notify + CyclicBarrier It seemed worth a try to replace the first cyclic barrier await() with a simple wait/notify mechanism: main() { // create the barrier // create Runable for thread, tell it about the barrier // start the threads while( ... ) { // tell threads about the work // for each: workerThreadRunnable.setWorkItem( ... ); // ... now worker threads work on the work... // wait for worker threads to finish barrier.await(); } } class WorkerThreadRunnable implements Runnable { CyclicBarrier barrier; @NotNull volatile private Callable<Integer> workItem; WorkerThreadRunnable( CyclicBarrier barrier ) { this.barrier = barrier; this.workItem = NO_WORK; } final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { synchronized( this ) { workItem = callable; notify(); } } public void run() { while( true ) { // wait for work while( true ) { synchronized( this ) { if( workItem != NO_WORK ) break; try { wait(); } catch( InterruptedException e ) { e.printStackTrace(); } } } // do the work ... // wait for everyone else to finish barrier.await(); } } } Again, this works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.4% 80% 6.3 16k 4.6% 60% 30.1 4096 8.6% 41% 98.5 1024 12% 23% 202 256 14% 11.6% 299 64 14% 10.0% 518 16 14.8% 8.7% 679 The throughput for small work items is still much worse than that of the ExecutorService, but about 2x that of the CyclicBarrier. Eliminating one CyclicBarrier eliminates half of the gap. V4 - Busy wait instead of wait/notify Since this app is the primary one running on the system and the cores idle anyway if they're not busy with a work item, why not try a busy wait for work items in each thread, even if that spins the CPU needlessly. The worker thread code changes as follows: class WorkerThreadRunnable implements Runnable { // as before final protected void setWorkItem( @NotNull final Callable<Integer> callable ) { workItem = callable; } public void run() { while( true ) { // busy-wait for work while( true ) { if( workItem != NO_WORK ) break; } // do the work ... // wait for everyone else to finish barrier.await(); } } } Also works well functionally (it does what it should). blocksize | system | user | cycles/sec 256k 1.9% 85% 1.30 64k 2.2% 81% 6.3 16k 4.2% 62% 33 4096 7.5% 40% 107 1024 10.4% 23% 210 256 12.0% 12.0% 310 64 11.9% 10.2% 550 16 12.2% 8.6% 741 For small work items, this increases throughput by a further 10% over the CyclicBarrier + wait/notify variant, which is not insignificant. But it is still much lower-throughput than V1 with the ExecutorService. V5 - ? So what is the best synchronization mechanism for such a (presumably not uncommon) problem? I am weary of writing my own sync mechanism to completely replace ExecutorService (assuming that it is too generic and there has to be something that can still be taken out to make it more efficient). It is not my area of expertise and I'm concerned that I'd spend a lot of time debugging it (since I'm not even sure my wait/notify and busy wait variants are correct) for uncertain gain. Any advice would be greatly appreciated.

    Read the article

  • Flex URLRequest Timeout

    - by MooCow
    I have a Flex program that gets a JSON array from a PHP script. The PHP script doesn't contain just a simple JSON array but it grabs data from Activecollab and do some work on the data before encoding the data. The first test involve a small JSON array that took a short time to encode by PHP. However, when I try to scale up the test, the Flash movie will crash trying to load the JSON data from PHP. There's no code difference between the tests, just the amount of data and amount of time it takes PHP to encode. Am I looking at a memory problem or a time out problem? PS: When I call the PHP script in Firefox, it doesn't time out and still return a JSON array. It just took awhile to return the array.

    Read the article

  • Doubt about the Intel's IA-32 software developer manual

    - by Francesco Turco
    I'm studying the Intel's IA-32 software developer manual. In particular, I'm reading the following manual: http://www.intel.com/Assets/PDF/manual/253666.pdf. Let's take for example the ADD instruction. On page 79 it is written that you can an r8 (8-bit register) to an r/m8 (8-bit register or memory location). A few rows below, it is also written that you can add an r/m8 to an r8. The question is: if I add two 8-bit registers, which instruction I am using? Thanks.

    Read the article

  • Is it possible to stream a file to and from servers without holding the data in ram?

    - by Chris Denman
    Hi everyone! PHP question (new to PHP after 10 years of Perl, arrggghhh!). I have a 100mb file that I want to send to another server. I have managed to read the file in and "post" it without curl (cannot use curl for this app). Everything is working fine on smaller files. However, with the larger files, PHP complains about not being able to allocate memory. Is there a way to open a file, line by line, and send it as a post ALSO line by line? This way nothing is held in ram thus preventing my errors and getting around strict limitations. Chris

    Read the article

  • Why is Visual Studio 2008 stuck in debug mode when compiling

    - by Mark
    I have a .NET project that for some reason gets stuck in debug mode. I've changed the compile mode from debug to release in the toolbar, but my project ends up in the debug directory anyway. Seems like VS is not updating the SLN file or something. Please help! The reason I am asking about this is because it seems that there are weak references "ENCList" clogging up memory when my program runs, and they seem to be created when .NET apps are compiled in debug (or so says other sources I've found online). -Mark

    Read the article

< Previous Page | 465 466 467 468 469 470 471 472 473 474 475 476  | Next Page >