Search Results

Search found 1977 results on 80 pages for 'concurrent modification'.

Page 49/80 | < Previous Page | 45 46 47 48 49 50 51 52 53 54 55 56  | Next Page >

  • best practice for passing many arguments to method ?

    - by Tony
    Occasionally , we have to write methods that receive many many arguments , for example : public void doSomething(Object objA , Object objectB ,Date date1 ,Date date2 ,String str1 ,String str2 ) { } When I encounter this kind of problem , I often encapsulate arguments into a map. Map<Object,Object> params = new HashMap<Object,Object>(); params.put("objA",ObjA) ; ...... public void doSomething(Map<Object,Object> params) { // extracting params Object objA = (Object)params.get("objA"); ...... } This is not a good practice , encapsulate params into a map is totally a waste of efficiency. The good thing is , the clean signature , easy to add other params with fewest modification . what's the best practice for this kind of problem ?

    Read the article

  • While using ConcurrentQueue, trying to dequeue while looping through in parallel

    - by James Black
    I am using the parallel data structures in my .NET 4 application and I have a ConcurrentQueue that gets added to while I am processing through it. I want to do something like: personqueue.AsParallel().WithDegreeOfParallelism(20).ForAll(i => ... ); as I make database calls to save the data, so I am limiting the number of concurrent threads. But, I expect that the ForAll isn't going to dequeue, and I am concerned about just doing ForAll(i => { personqueue.personqueue.TryDequeue(...); ... }); as there is no guarantee that I am popping off the correct one. So, how can I iterate through the collection and dequeue, in a parallel fashion. Or, would it be better to use PLINQ to do this processing, in parallel?

    Read the article

  • Script Speed vs Memory Usage

    - by Doug Neiner
    I am working on an image generation script in PHP and have gotten it working two ways. One way is slow but uses a limited amount of memory, the second is much faster, but uses 6x the memory . There is no leakage in either script (as far as I can tell). In a limited benchmark, here is how they performed: -------------------------------------------- METHOD | TOTAL TIME | PEAK MEMORY | IMAGES -------------------------------------------- One | 65.626 | 540,036 | 200 Two | 20.207 | 3,269,600 | 200 -------------------------------------------- And here is the average of the previous numbers (if you don't want to do your own math): -------------------------------------------- METHOD | TOTAL TIME | PEAK MEMORY | IMAGES -------------------------------------------- One | 0.328 | 540,036 | 1 Two | 0.101 | 3,269,600 | 1 -------------------------------------------- Which method should I use and why? I anticipate this being used by a high volume of users, with each user making 10-20 requests to this script during a normal visit. I am leaning toward the faster method because though it uses more memory, it is for a 1/3 of the time and would reduce the number of concurrent requests.

    Read the article

  • What is the best way to make a schedule in MFC

    - by Vanwaril
    I have a list of items that are each associated with a start and end time and date. What I want to do is, given a time and date range, display only the items that fall within that window, even partially. What I'm doing is creating a CListCtrl with all the items in it and the CListCtrl is sorted by start time by default. But given a time range, I don't know how to search for the first item that is within the range. Another problem with the list control is it displays as a list, whereas it would be nice if there was a control that could also show things that are concurrent side by side. I'm doing this within a dialog application.

    Read the article

  • Why doesn't ConcurrentQueue<T>.Count return 0 when IsEmpty == true?

    - by DanTup - Danny Tuppeny
    I was reading about the new concurrent collection classes in .NET 4 on James Michael Hare's blog, and the page talking about ConcurrentQueue<T> says: It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. I'm curious - if there is a reason to use IsEmpty instead of comparing Count to 0, why does the class not internally check IsEmpty and return 0 before doing any of the expensive work to count? E.g.: public int Count { get { // Check IsEmpty so we can bail out quicker if (this.IsEmpty) return 0; // Rest of "expensive" counting code } } It seems strange to suggest this if it could be "fixed" so easily with no side-effects?

    Read the article

  • HBase as web app backend

    - by NathanD
    Can anyone advise if it is a good idea to have HBase as primary data source for web-based application? My primary concern is HBase's response time to queries. Is it possible to have sub-second response? edit: more details about the app itself. Amount of data: ~500GB of text data, expect to reach 1TB soon Number of concurrent users using the app: up to 50 The app will be used to present reports about data stored in HBase, like how many times keyword "X" occured in last 24h. For ~80% of requests from that app I will know the exact key, 20% will be scans (I'm looking into HBase schema design related topics to make it run fast)

    Read the article

  • Threads to make video out of images

    - by masood
    updates: I think/ suspect the imageIO is not thread safe. shared by all threads. the read() call might use resources that are also shared. Thus it will give the performance of a single thread no matter how many threads used. ? if its correct . what is the solution (in practical code) Single request and response model at one time do not utilizes full network/internet bandwidth, thus resulting in low performance. (benchmark is of half speed utilization or even lower) This is to make a video out of an IP cam that gives a new image on each request. http://149.5.43.10:8001/snapshot.jpg It makes a delay of 3 - 8 seconds no matter what I do. Changed thread no. and thread time intervals, debugged the code by System.out.println statements to see if threads work. All seems normal. Any help? Please show some practical code. You may modify mine. This code works (javascript) with much smoother frame rate and max bandwidth usage. but the later code (java) dont. same 3 to 8 seconds gap. <!DOCTYPE html> <html> <head> <script type="text/javascript"> (function(){ var img="/*url*/"; var interval=50; var pointer=0; function showImg(image,idx) { if(idx<=pointer) return; document.body.replaceChild(image,document.getElementsByTagName("img")[0]); pointer=idx; preload(); } function preload() { var cache=null,idx=0;; for(var i=0;i<5;i++) { idx=Date.now()+interval*(i+1); cache=new Image(); cache.onload=(function(ele,idx){return function(){showImg(ele,idx);};})(cache,idx); cache.src=img+"?"+idx; } } window.onload=function(){ document.getElementsByTagName("img")[0].onload=preload; document.getElementsByTagName("img")[0].src="/*initial url*/"; }; })(); </script> </head> <body> <img /> </body> </html> and of java (with problem) : package camba; import java.applet.Applet; import java.awt.Button; import java.awt.Graphics; import java.awt.Image; import java.awt.Label; import java.awt.Panel; import java.awt.TextField; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.net.URL; import java.security.Timestamp; import java.util.Date; import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicBoolean; import javax.imageio.ImageIO; public class Camba extends Applet implements ActionListener{ Image img; TextField textField; Label label; Button start,stop; boolean terminate = false; long viewTime; public void init(){ label = new Label("please enter camera URL "); add(label); textField = new TextField(30); add(textField); start = new Button("Start"); add(start); start.addActionListener(this); stop = new Button("Stop"); add(stop); stop.addActionListener(this); } public void actionPerformed(ActionEvent e){ Button source = (Button)e.getSource(); if(source.getLabel() == "Start"){ for (int i = 0; i < 7; i++) { myThread(50*i); } System.out.println("start..."); } if(source.getLabel() == "Stop"){ terminate = true; System.out.println("stop..."); } } public void paint(Graphics g) { update(g); } public void update(Graphics g){ try{ viewTime = System.currentTimeMillis(); g.drawImage(img, 100, 100, this); } catch(Exception e) { e.printStackTrace(); } } public void myThread(final int sleepTime){ new Thread(new Runnable() { public void run() { while(!terminate){ try { TimeUnit.MILLISECONDS.sleep(sleepTime); } catch (InterruptedException ex) { ex.printStackTrace(); } long requestTime= 0; Image tempImage = null; try { URL pic = null; requestTime= System.currentTimeMillis(); pic = new URL(getDocumentBase(), textField.getText()); tempImage = ImageIO.read(pic); } catch(Exception e) { e.printStackTrace(); } if(requestTime >= /*last view time*/viewTime){ img = tempImage; Camba.this.repaint(); } } }}).start(); System.out.println("thread started..."); } }

    Read the article

  • Setting creation or change timestamps

    - by Thanatos
    Using utimes, futimes, futimens, etc., it is possible to set the access and modification timestamps on a file. Is there a function to set change timestamps? (I understand the cyclic nature of wanting to change the change timestamp, but think archiving software - it would be nice to restore a file exactly as it was.) Are there any functions at all for creation timestamps? (I realize that ext2 does not support this, but I was wondering if Linux did, for those filesystems that do support it.) If it's not possible, what is the reasoning behind it not being so?

    Read the article

  • Uniquely identify two instances of one browser that share Session state?

    - by jdk
    I want to make sure that a user isn't editing the same form data in two different browser tabs or windows (of the same web browser instance). It's to stop the user from stupidly overwriting their own data as they continue through a very long form process. On the server ongoing data input through the screens is collected into the Session. Assume for any browser, all tabs and windows run in the same instance of it (i.e. not each in a separate process). Obviously the browser tabs and windows share the same cookies in this scenario so cookie modification seems out of the question for viable solutions. This is also the reason they shared the same session. Considering that the form is already created and this is one of the final touches, how can I use ASP.NET, hopefully easily, to oversee this "feature"?

    Read the article

  • Python: Taking an array and break it into subarrays based on some criteria

    - by randombits
    I have an array of files. I'd like to be able to break that array down into one array with multiple subarrays, each subarray contains files that were created on the same day. So right now if the array contains files from March 1 - March 31, I'd like to have an array with 31 subarrays (assuming there is at least 1 file for each day). In the long run, I'm trying to find the file from each day with the latest creation/modification time. If there is a way to bundle that into the iterations that are required above to save some CPU cycles, that would be even more ideal. Then I'd have one flat array with 31 files, one for each day, for the latest file created on each individual day.

    Read the article

  • How to manage db connections on server?

    - by simpatico
    I have a severe problem with my database connection in my web application. Since I use a single database connection for the whole application from singleton Database class, if i try concurrent db operations (two users) the database rollsback the transactions. This is my static method used: All threads/servlets call static Database.doSomething(...) methods, which in turn call the the below method. private static /* synchronized*/ Connection getConnection(final boolean autoCommit) throws SQLException { if (con == null) { con = new MyRegistrationBean().getConnection(); } con.setAutoCommit(true); //TODO return con; } What's the recommended way to manage this db connection/s I have, so that I don't incurr in the same problem.

    Read the article

  • ASP.NET Thread Safety in aspx.cs code behind file

    - by Tim Michalski
    I am thinking of adding a DataContext as a member variable to my aspx.cs code-behind class for executing LinqToSql queries. Is this thread safe? I am not sure if a new instance of this code-behind class is created for each HTTP request, or if the instance is shared amongst all request threads? My fear is that I will get 10 simultaneous concurrent http requests that will be using the same database session. public partial class MyPage : System.Web.UI.Page { private DataContext myDB = new DataContext(); protected void MyAction_Click(object sender, EventArgs e) { myDB.DoWork(); } }

    Read the article

  • Why avoid pessimistic locking in a version control system?

    - by raven
    Based on a few posts I've read concerning version control, it seems people think pessimistic locking in a version control system is a bad thing. Why? I understand that it prevents one developer from submitting a change while another has the file checked out, but so what? If your code files are so big that you constantly have more than one person working on them at the same time, I submit that you should reorganize your code. Break it up into smaller functional units. Integration of concurrent code changes is a tedious and error-prone process even with the tools a good version control system provides to make it easier. I think it should be avoided if at all possible. So, why is pessimistic locking discouraged?

    Read the article

  • Flymake quits right ahead after loading with js2-mode

    - by artistoex
    When opening .js files, js2-mode and, subsequently, flymake-js is automatically loaded. But flymake unloads right ahead with the message Toggling flymake-mode off; better pass an explicit argument. However, when enabling it manually, using M-x flymake-mode, it keeps activated. Has anybody encountered similar behavior and has fixed it? My setup: I followed the instructions on emacswiki to set up Flymake to work with the most recent js2-mode with a little modification: (add-hook 'js2-mode-hook '(lambda () (flymake-js-load))) instead of (add-hook 'javascript-mode-hook '(lambda () (flymake-js-load)))

    Read the article

  • Which one is better apporach comet or ajax?

    - by Rajesh Rolen- DotNet Developer
    i need to update client on any changes occurred on server. for that i found 2 approach. 1. using ajax which is also known as reverse ajax for this purpose. 2. using COMET. but i don't know exact difference in both. my site contains news content and i want that news to be automatically updates when new news is entered by my CMS application. i have got hundreds of concurrent users on my web application. please suggest me which approach should i use to get best solution. also please provide me good example's like for that so that i can implement it. NOTE: i am using .net framework 2.0 but if its not possible in 2.0 then can also move to 3.5 Thanks.

    Read the article

  • How do I modify gitstats to only utilize a specified file extension for it's statistics?

    - by Fake Code Monkey Rashid
    Hello good people! The website of the statistics generator in question is: http://gitstats.sourceforge.net/ It's git repo can be cloned from: git clone git://repo.or.cz/gitstats.git What I want to do is something like: ./gitstatus --ext=".py" /input/foo /output/bar Failing being able to easily pass the above option without heavy modification, I'd just hardcore the file extentsion I want to be included. However, I'm unsure of the relevant section of code to modify and even if I did no, I'm unsure of how to start such modifications. It's seems like it'd be rather simple but alas...

    Read the article

  • Chat Server with sockets in C

    - by Andrew
    I'm trying to write a chat server in C that allows communication between two clients using POSIX sockets. I'm not sure I have a good grasp on this concept or how I should set up the communication protocol between the clients and the server. I know I need one socket to bind() the server port to so I can accept incoming connections from clients, but in order to have two clients connected at the same time do I need to create a socket for each of these clients when I accept() or should I accept() a client and then fork() so I can have another client accept? I'm not worried about concurrent chatting yet, it's more of a ping-pong approach where the clients need to wait for a recv() after they send() before they can type a new message.

    Read the article

  • designing data structures for an address book in C program??

    - by osabri
    i want that the number of address book item is not known in advance, i am thinking to use linked list is it the right choice?? "the user can enter new person data, or print the data for a given name, the asking data need not be a name but also an address on a telephone number, the program prints the whole information about a person, print the content of the book in alphabetical order. Store some data in a file; retrieve it and safe it after modification Program should write a file to the disk and retrieve the file from it. Program should be called with arguments. i will use malloc but i don't know when and how? somebody did similar task or have an idea can help me plz

    Read the article

  • oracle display for every stored procedure the execution time

    - by CC
    Hi all. I'm working on a stored procedure. Inside this one, there are many call to the other stored procedures. There are a bunch of them. I was wondering if there is a option to be able to have the execution time of every stored procedure involved, every function (with a start and end time, ior something like that). The idea is that I need to optimise it and I should touch every part, and since I not sure where is the longest execution time, is a bit difficult. And after a modification I would like the see the hole process if it's shorter or not. If I call the procedure from unix, using sql plus, I have no log. If I call it from TOAD, it's blocked until the end. Any idea? I'm not a dba, so I don't have many rights on the database, I'm just a regular user. Thanks for any advice. C.C.

    Read the article

  • What is my problem with ASP.NET pubslishing?

    - by Shankarooni
    I am done testing my site and I want to upload it to a site like this http://www.university.edu/mydepartment/myname the admin told me the server runs on .NET 3.5. So i used Linq ... now i tried to upload the site by two ways: when i just copy everything (with modification of web.config database settings) i get an error: CS0246: The type or namespace name 'DataClassesDataContext' could not be found (are you missing a using directive or an assembly reference?) Version Information: Microsoft .NET Framework Version:2.0.50727.3082; ASP.NET Version:2.0.50727.3082 Note here it says version 2.0 did he just lie to me? or its my configuration mistake? anyway, i added the reference, nothing changes. I tried also publishing (Build, publish) with option to keep the pre-comiled site updatable, and I get one line saying: this is a makefile and should be deleted! what is going on?

    Read the article

  • iPhone: One Object, One Thread

    - by GingerBreadMane
    On the iPhone, I would like to do some operations on an image in a separate thread. Rather than dealing with semiphores, locking, etc., I'd like to use the 'One Object, One Thread' method of safely writing this concurrent operation. I'm not sure what is the correct way to copy my object into a new thread so that the object is not accessed in the main thread. Do I use the 'copy' method? If so, do I do this before the thread or inside the thread? ... -(void)someMethod{ UIImage *myImage; [NSThread detachNewThreadSelector:@selector(getRotatedImage:) toTarget:self withObject:myImage]; } -(void)getRotatedImage:(UIImage *)image{ ... ... UIImage *copiedImage = [image copy]; ... ... }

    Read the article

  • (win32) What to do when a file remains left open when a remote application crashes or forgets to clo

    - by Stephane R.
    Hi I have not worked so much with files: I am wondering about possible issues with accessing remote files on another computer. What if the distant application crashes and doesn't close the file ? My aim is to use this win32 function: HFILE WINAPI OpenFile(LPCSTR lpFileName, LPOFSTRUCT lpReOpenBuff, UINT uStyle); Using the flag OF_SHARE_EXCLUSIVE assures me that any concurrent access will be denied (because several machines are writing to this file from time to time). But what if the file is left open ? (application crash for example ?) How to put the file back to normal ?

    Read the article

  • MySQL with Java: Open connection only if possible

    - by emempe
    I'm running a database-heavy Java application on a cluster, using Connector/J 5.1.14. Therefore, I have up to 150 concurrent tasks accessing the same MySQL database. I get the following error: Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Too many connections This happens because the server can't handle so many connections. I can't change anything on the database server. So my question is: Can I check if a connection is possible BEFORE I actually connect to the database? Something like this (pseudo code): check database for open connection slots if (slot is free) { Connection cn = DriverManager.getConnection(url, username, password); } else { wait ... } Cheers

    Read the article

  • Query for Joining Two Tables With Possible Multiple Mapping

    - by Dharmendra Mohapatra
    First_table srno wono Actual_Start_Date Actual_End_Date 1 31 2012-06-02 2012-06-05 2 32 2012-06-05 2012-06-22 3 33 2012-06-11 2012-06-23 4 34 2012-06-23 2012-06-30 5 A-2 2012-06-24 2012-06-25 6 BU 2012-06-24 2012-06-26 7 40 2012-06-25 2012-06-27 second_table srno wono Base_start_date Base_end_date uploadhistoryid 1 31 2012-06-05 2012-06-05 1 2 32 2012-06-11 2012-06-12 2 3 32 2012-06-15 2012-06-17 3 4 32 2012-06-18 2012-06-20 4 5 33 2012-06-22 2012-06-25 5 5 33 2012-06-23 2012-06-25 5 Result Required SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO ALTER PROCEDURE [dbo].[Reports_Subanalysis] ( @WONo VARCHAR(20) ) AS BEGIN SELECT 'SAT' AS stage, s.Base_start_date AS start_date, s.Base_end_date AS end_date, f.Actual_Start_Date AS Actual_Start_Date, f.Actual_end_Date AS Actual_End_Date FROM First_table f, second_table B WHERE A.wOno=B.nOno AND f.uploadhistoryid in (SELECT min(uploadhistoryid) FROM second_table C WHERE f.wono = C.wono) AND b.wono=@WONo END when I pass '32' Result stage start_date end_date Actual_Start_Date Actual_End_Date SAT 2012-06-11 2012-06-12 2012-06-05 2012-06-05 how Can I get the result like this when I pass non matching value like 'BU' stage start_date end_date Actual_Start_Date Actual_End_Date SAT NULL NULL 2012-06-24 2012-06-26 What modification do I need in my routine?

    Read the article

  • How do I choose a database?

    - by liamzebedee
    I need a comparison table of some sort for database varieties (MySQL, SQLite etc.). I can't find one. My use case is, I am implementing storage of objects in a distributed hash table. I need a database solution that is: Fast for sorting Simplistic (no users, preferably no additional structures like multiple tables etc.) Concurrent (if possible) Multi-platform File based (not stored in memory primarily) Centralized I will be programming in Go. As I understand, I believe I need what is called a Document Orientated Database, because I am storing objects, identified by keys. EDIT: While I am implementing a DHT, I will also be storing metadata about the objects, such as access counts etc. It would also be preferable to have TLL (time to live)

    Read the article

< Previous Page | 45 46 47 48 49 50 51 52 53 54 55 56  | Next Page >