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• gmail app 504 server timeout

  - by Hui

  this is the part of code I use for getting info from gmail, it's working alright on my localhost, but somehow when i deploy it online, I got 504 gateway timeout error. Did I missed something in my code? can someone give some advices , thanks a lot public class GetGmail { static String last = null; public static ArrayList run(String username, String password, String lastloggin)throws Exception { ArrayList result = null; System.out.println("Getting Gmail......"); last = lastloggin; Properties props = System.getProperties(); props.setProperty("mail.store.protocol", "imaps"); try { Session session = Session.getDefaultInstance(props, null); Store store = session.getStore("imaps"); store.connect("imap.googlemail.com", username, password); result = readMessage(store); store.close(); } catch (NoSuchProviderException e) { e.printStackTrace(); return null; } catch (MessagingException e) { e.printStackTrace(); return null; } return result; } }

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• How can I use timer to stop another thread? [on hold]

  - by Haoda Fu

  How can we stop another thread based on a timer? I was trying to use timer to stop another thread. But I didn't got a success. To better illustrate my point and for your easy to understand the key issue. I made the following sample example. Your help is really appreciated using System; using System.Collections.Generic; using System.Text; using System.Threading; using System.Timers; namespace TestCodes { public static class Program { private static Thread nT = new Thread(PrintABC); private static System.Timers.Timer aTimer; public static void Main() { aTimer = new System.Timers.Timer(1000); aTimer.Elapsed += TimerCallback; aTimer.Interval = 1000; aTimer.Enabled = true; nT.Start(); Console.ReadLine(); } private static void TimerCallback(Object o, ElapsedEventArgs e) { nT.Join(); Console.WriteLine("Complete the PrintABC"); GC.Collect(); } private static void PrintABC() { for (int iter = 1; iter < 300; iter++) { Console.WriteLine(iter+"abc"); Console.ReadKey(); //Thread.Sleep(100); } } } }

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• Deadlock Analysis in NetBeans 8

  - by Geertjan

  Lock contention profiling is very important in multi-core environments. Lock contention occurs when a thread tries to acquire a lock while another thread is holding it, forcing it to wait. Lock contentions result in deadlocks. Multi-core environments have even more threads to deal with, causing an increased likelihood of lock contentions. In NetBeans 8, the NetBeans Profiler has new support for displaying detailed information about lock contention, i.e., the relationship between the threads that are locked. After all, whenever there's a deadlock, in any aspect of interaction, e.g., a political deadlock, it helps to be able to point to the responsible party or, at least, the order in which events happened resulting in the deadlock. As an example, let's take the handy Deadlock sample code from the Java Tutorial and look at the tools in NetBeans IDE for identifying and analyzing the code. The description of the deadlock is nice: Alphonse and Gaston are friends, and great believers in courtesy. A strict rule of courtesy is that when you bow to a friend, you must remain bowed until your friend has a chance to return the bow. Unfortunately, this rule does not account for the possibility that two friends might bow to each other at the same time. To help identify who bowed first or, at least, the order in which bowing took place, right-click the file and choose "Profile File". In the Profile Task Manager, make the choices below: When you have clicked Run, the Threads window shows the two threads are blocked, i.e., the red "Monitor" lines tell you that the related threads are blocked while trying to enter a synchronized method or block: But which thread is holding the lock? Which one is blocked by the other? The above visualization does not answer these questions. New in NetBeans 8 is that you can analyze the deadlock in the new Lock Contention window to determine which of the threads is responsible for the lock: Here is the code that simulates the lock, very slightly tweaked at the end, where I use "setName" on the threads, so that it's even easier to analyze the threads in the relevant NetBeans tools. Also, I converted the anonymous inner Runnables to lambda expressions. package org.demo; public class Deadlock { static class Friend { private final String name; public Friend(String name) { this.name = name; } public String getName() { return this.name; } public synchronized void bow(Friend bower) { System.out.format("%s: %s" + " has bowed to me!%n", this.name, bower.getName()); bower.bowBack(this); } public synchronized void bowBack(Friend bower) { System.out.format("%s: %s" + " has bowed back to me!%n", this.name, bower.getName()); } } public static void main(String[] args) { final Friend alphonse = new Friend("Alphonse"); final Friend gaston = new Friend("Gaston"); Thread t1 = new Thread(() -> { alphonse.bow(gaston); }); t1.setName("Alphonse bows to Gaston"); t1.start(); Thread t2 = new Thread(() -> { gaston.bow(alphonse); }); t2.setName("Gaston bows to Alphonse"); t2.start(); } } In the above code, it's extremely likely that both threads will block when they attempt to invoke bowBack. Neither block will ever end, because each thread is waiting for the other to exit bow. Note: As you can see, it really helps to use "Thread.setName", everywhere, wherever you're creating a Thread in your code, since the tools in the IDE become a lot more meaningful when you've defined the name of the thread because otherwise the Profiler will be forced to use thread names like "thread-5" and "thread-6", i.e., based on the order of the threads, which is kind of meaningless. (Normally, except in a simple demo scenario like the above, you're not starting the threads in the same class, so you have no idea at all what "thread-5" and "thread-6" mean because you don't know the order in which the threads were started.) Slightly more compact: Thread t1 = new Thread(() -> { alphonse.bow(gaston); },"Alphonse bows to Gaston"); t1.start(); Thread t2 = new Thread(() -> { gaston.bow(alphonse); },"Gaston bows to Alphonse"); t2.start();

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• Why does C# thread die?

  - by JackN

  This is my 1st C# project so I may be doing something obviously improper in the code below. I am using .NET, WinForms (I think), and this is a desktop application until I get the bugs out. UpdateGui() uses Invoke((MethodInvoker)delegate to update various GUI controls based on received serial data and sends a GetStatus() command out the serial port 4 times a second. Thread Read() reads the response from serial port whenever it arrives which should be near immediate. SerialPortFixer is a SerialPort IOException Workaround in C# I found at http://zachsaw.blogspot.com/2010/07/serialport-ioexception-workaround-in-c.html. After one or both threads die I'll see something like The thread 0x1288 has exited with code 0 (0x0). in the debug code output. Why do UpdateGui() and/or Read() eventually die? public partial class UpdateStatus : Form { private readonly byte[] Command = new byte[32]; private readonly byte[] Status = new byte[32]; readonly Thread readThread; private static readonly Mutex commandMutex = new Mutex(); private static readonly Mutex statusMutex = new Mutex(); ... public UpdateStatus() { InitializeComponent(); SerialPortFixer.Execute("COM2"); if (serialPort1.IsOpen) { serialPort1.Close(); } try { serialPort1.Open(); } catch (Exception e) { labelWarning.Text = LOST_COMMUNICATIONS + e; labelStatus.Text = LOST_COMMUNICATIONS + e; labelWarning.Visible = true; } readThread = new Thread(Read); readThread.Start(); new Timer(UpdateGui, null, 0, 250); } static void ProcessStatus(byte[] status) { Status.State = (State) status[4]; Status.Speed = status[6]; // MSB Status.Speed *= 256; Status.Speed += status[5]; var Speed = Status.Speed/GEAR_RATIO; Status.Speed = (int) Speed; ... } public void Read() { while (serialPort1 != null) { try { serialPort1.Read(Status, 0, 1); if (Status[0] != StartCharacter[0]) continue; serialPort1.Read(Status, 1, 1); if (Status[1] != StartCharacter[1]) continue; serialPort1.Read(Status, 2, 1); if (Status[2] != (int)Command.GetStatus) continue; serialPort1.Read(Status, 3, 1); ... statusMutex.WaitOne(); ProcessStatus(Status); Status.update = true; statusMutex.ReleaseMutex(); } catch (Exception e) { Console.WriteLine(@"ERROR! Read() " + e); } } } public void GetStatus() { const int parameterLength = 0; // For GetStatus statusMutex.WaitOne(); Status.update = false; statusMutex.ReleaseMutex(); commandMutex.WaitOne(); if (!SendCommand(Command.GetStatus, parameterLength)) { Console.WriteLine(@"ERROR! SendCommand(GetStatus)"); } commandMutex.ReleaseMutex(); } private void UpdateGui(object x) { try { Invoke((MethodInvoker)delegate { Text = DateTime.Now.ToLongTimeString(); statusMutex.WaitOne(); if (Status.update) { if (Status.Speed > progressBarSpeed.Maximum) { Status.Speed = progressBarSpeed.Maximum; } progressBarSpeed.Value = Status.Speed; labelSpeed.Text = Status.Speed + RPM; ... } else { labelWarning.Text = LOST_COMMUNICATIONS; labelStatus.Text = LOST_COMMUNICATIONS; labelWarning.Visible = true; } statusMutex.ReleaseMutex(); GetStatus(); }); } catch (Exception e) { Console.WriteLine(@"ERROR! UpdateGui() " + e); } } }

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• C# thread functions not properly sharing a static data member

  - by Umer

  I have a class as following public class ScheduledUpdater { private static Queue<int> PendingIDs = new Queue<int>(); private static bool UpdateThreadRunning = false; private static bool IsGetAndSaveScheduledUpdateRunning = false; private static DataTable ScheduleConfiguration; private static Thread updateRefTableThread; private static Thread threadToGetAndSaveScheduledUpdate; public static void ProcessScheduledUpdates(int ID) { //do some stuff // if ( updateRefTableThread not already running) // execute updateRefTableThread = new Thread(new ThreadStart(UpdateSchedulingRefTableInThrear)); // execute updateRefTableThread.Start(); //do some stuff GetAndSaveScheduledUpdate(ID) } private static void UpdateSchedulingRefTableInThrear() { UpdateSchedulingRefTable(); } public static void UpdateSchedulingRefTable() { // read DB and update ScheduleConfiguration string query = " SELECT ID,TimeToSendEmail FROM TBLa WHERE MODE = 'WebServiceOrder' AND BDELETE = false "; clsCommandBuilder commandBuilder = new clsCommandBuilder(); DataSet ds = commandBuilder.GetDataSet(query); if (ds != null && ds.Tables.Count > 0 && ds.Tables[0].Rows.Count > 0) { List<string> lstIDs = new List<string>(); for (int i = 0; i < ds.Tables[0].Rows.Count; i++) { lstIDs.Add(ds.Tables[0].Rows[i]["ID"].ToString()); if (LastEmailSend.Contains(ds.Tables[0].Rows[i]["ID"].ToString())) LastEmailSend[ds.Tables[0].Rows[i]["ID"].ToString()] = ds.Tables[0].Rows[i]["TimeToSendEmail"].ToString(); else LastEmailSend.Add(ds.Tables[0].Rows[i]["ID"].ToString(), ds.Tables[0].Rows[i]["TimeToSendEmail"].ToString()); } if (lstIDs.Count > 0) { string Ids = string.Join(",", lstIDs.ToArray()).Trim(','); dhDBNames dbNames = new dhDBNames(); dbNames.Default_DB_Name = dbNames.ControlDB; dhGeneralPurpose dhGeneral = new dhGeneralPurpose(); dhGeneral.StringDH = Ids; DataSet result = commandBuilder.GetDataSet(dbNames, (object)dhGeneral, "xmlGetConfigurations"); if (result != null && result.Tables.Count > 0) { if (ScheduleConfiguration != null) ScheduleConfiguration.Clear(); ScheduleConfiguration = result.Tables[0]; } } } } public static void GetAndSaveScheduledUpdate(int ID) { //use ScheduleConfiguration if (ScheduleConfiguration == null)[1] UpdateSchedulingRefTable(); DataRow[] result = ScheduleConfiguration.Select("ID = "+ID); //then for each result row, i add this to a static Queue PendingIDs } } The function UpdateSchedulingRefTable can be called any time from outside world (for instance if someone updates the schedule configuration manually) ProcessScheduledUpdates is called from a windows service every other minute. Problem: Datatable ScheduleConfiguration is updated in the UpdateSchedulingRefTable (called from outside world - say manually) but when i try to use Datatable ScheduleConfiguration in GetAndSaveScheduledUpdate, i get the older version of values.... What am I missing in this stuff??? About EDIT: I thought the stuff i have not shown is quite obvious and possibly not desired, perhaps my structure is wrong :) and sorry for incorrect code previously, i made a simple function call as a thread initialization... sorry for my code indentation too because i don't know how to format whole block...

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• Update UI from an event with a thread

  - by tyrone-tudehope

  Im working on a small application to try out an idea that I have. The idea is to periodically update the UI when event of some sort occurs. In the demo I've created, I'm updating a ProgressDialog every 2 seconds for 15 turns. The problem I am having, which I don't quite understand is that when an event is handled, I send a message to the handler which is supposed to update the message in the ProgressDialog. When this happens however, I get an exception which states that I can't update the UI from that thread. The following code appears in my Activity: ProgressDialog diag; String diagMessage = "Started loading..."; final static int MESSAGE_DATA_RECEIVED = 0; final static int MESSAGE_RECEIVE_COMPLETED = 1; final Handler handler = new Handler(){ @Override public void handleMessage(Message msg){ diag.setMessage(diagMessage); switch(msg.what){ case MESSAGE_DATA_RECEIVED: break; case MESSAGE_RECEIVE_COMPLETED: dismissDialog(); killDialog(); break; } } }; Boolean isRunning = false; /** * Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setupDialog(); if(isRunning){ showDialog(); } setContentView(R.layout.main); } void setupDialog(){ if(diag == null){ diag = new ProgressDialog(ThreadLoading.this); diag.setMessage(diagMessage); } } void showDialog(){ isRunning = true; if(diag != null && !diag.isShowing()){ diag.show(); } } void dismissDialog(){ if(diag != null && diag.isShowing()){ diag.dismiss(); } } void killDialog(){ isRunning = false; } public void onStart(){ super.onStart(); showDialog(); Thread background = new Thread(new Runnable(){ public void run(){ try{ final ThreadRunner tr = new ThreadRunner(); tr.setOnDataReceivedListener(new ThreadRunner.OnDataReceivedListener(){ public void onDataReceived(String message){ diagMessage = message; handler.handleMessage(handler.obtainMessage(MESSAGE_DATA_RECEIVED)); } }); tr.setOnDataDownloadCompletedEventListener(new ThreadRunner.OnDataDownloadCompletedListener(){ public void onDataDownloadCompleted(String message){ diagMessage = message; handler.handleMessage(handler.obtainMessage(MESSAGE_RECEIVE_COMPLETED)); } }); tr.runProcess(); } catch(Throwable t){ throw new RuntimeException(t); } } }); background.start(); } @Override public void onPause(){ super.onPause(); dismissDialog(); } For curiosity sake, here's the code for the ThreadRunner class: public interface OnDataReceivedListener { public void onDataReceived(String message); } public interface OnDataDownloadCompletedListener { public void onDataDownloadCompleted(String message); } private OnDataReceivedListener onDataReceivedEventListener; private OnDataDownloadCompletedListener onDataDownloadCompletedEventListener; int maxLoop = 15; int loopCount = 0; int sleepTime = 2000; public void setOnDataReceivedListener(OnDataReceivedListener onDataReceivedListener){ this.onDataReceivedEventListener = onDataReceivedListener; } public void setOnDataDownloadCompletedEventListener(OnDataDownloadCompletedListener onDataDownloadCompletedListener){ this.onDataDownloadCompletedEventListener = onDataDownloadCompletedListener; } public void runProcess(){ for(loopCount = 0; loopCount < maxLoop; loopCount++){ try{ Thread.sleep(sleepTime); onDataReceivedEventListener.onDataReceived(Integer.toString(loopCount)); } catch(Throwable t){ throw new RuntimeException(t); } } onDataDownloadCompletedEventListener.onDataDownloadCompleted("Download is completed"); } Am I missing something? The logic makes sense to me and it looks like everything should work, I'm using a handler to update the UI like it is recommended. Any help will be appreciated. Thanks, Tyrone P.S. I'm developing for Android 1.5

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• Handling a Long Running jsp request on the server using Ajax and threads

  - by John Blue

  I am trying to implement a solution for a long running process on the server where it is taking about 10 min to process a pdf generation request. The browser bored/timesout at the 5 mins. I was thinking to deal with this using a Ajax and threads. I am using regular javascript for ajax. But I am stuck with it. I have reached till the point where it sends the request to the servlet and the servlet starts the thread.Please see the below code public class HelloServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("POST request!!"); LongProcess longProcess = new LongProcess(); longProcess.setDaemon(true); longProcess.start(); request.getSession().setAttribute("longProcess", longProcess); request.getRequestDispatcher("index.jsp").forward(request, response); } } class LongProcess extends Thread { public void run() { System.out.println("Thread Started!!"); while (progress < 10) { try { sleep(2000); } catch (InterruptedException ignore) {} progress++; } } } Here is my AJax call <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html><head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>My Title</title> <script language="JavaScript" > function getXMLObject() //XML OBJECT { var xmlHttp = false; xmlHttp = new XMLHttpRequest(); //For Mozilla, Opera Browsers return xmlHttp; // Mandatory Statement returning the ajax object created } var xmlhttp = new getXMLObject(); //xmlhttp holds the ajax object function ajaxFunction() { xmlhttp.open("GET","HelloServlet" ,true); xmlhttp.onreadystatechange = handleServerResponse; xmlhttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded'); xmlhttp.send(null); } function handleServerResponse() { if (xmlhttp.readyState == 4) { if(xmlhttp.status == 200) { document.forms[0].myDiv.value = xmlhttp.responseText; setTimeout(ajaxFunction(), 2000); } else { alert("Error during AJAX call. Please try again"); } } } function openPDF() { document.forms[0].method = "POST"; document.forms[0].action = "HelloServlet"; document.forms[0].submit(); } function stopAjax(){ clearInterval(intervalID); } </script> </head> <body><form name="myForm"> <table><tr><td> <INPUT TYPE="BUTTON" NAME="Download" VALUE="Download Queue ( PDF )" onclick="openPDF();"> </td></tr> <tr><td> Current status: <div id="myDiv"></div>% </td></tr></table> </form></body></html> But I dont know how to proceed further like how will the thread communicate the browser that the process has complete and how should the ajax call me made and check the status of the request. Please let me know if I am missing some pieces. Any suggestion if helpful.

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• REST WCF service locks thread when called using AJAX in an ASP.Net site

  - by Jupaol

  I have a WCF REST service consumed in an ASP.Net site, from a page, using AJAX. I want to be able to call methods from my service async, which means I will have callback handlers in my javascript code and when the methods finish, the output will be updated. The methods should run in different threads, because each method will take different time to complete their task I have the code semi-working, but something strange is happening because the first time I execute the code after compiling, it works, running each call in a different threads but subsequent calls blocs the service, in such a way that each method call has to wait until the last call ends in order to execute the next one. And they are running on the same thread. I have had the same problem before when I was using Page Methods, and I solved it by disabling the session in the page but I have not figured it out how to do the same when consuming WCF REST services Note: Methods complete time (running them async should take only 7 sec and the result should be: Execute1 - Execute3 - Execute2) Execute1 -- 2 sec Execute2 -- 7 sec Execute3 -- 4 sec Output After compiling Output subsequent calls (this is the problem) I will post the code...I'll try to simplify it as much as I can Service Contract [ServiceContract( SessionMode = SessionMode.NotAllowed )] public interface IMyService { // I have other 3 methods like these: Execute2 and Execute3 [OperationContract] [WebInvoke( RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json, UriTemplate = "/Execute1", Method = "POST")] string Execute1(string param); } [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] [ServiceBehavior( InstanceContextMode = InstanceContextMode.PerCall )] public class MyService : IMyService { // I have other 3 methods like these: Execute2 (7 sec) and Execute3(4 sec) public string Execute1(string param) { var t = Observable.Start(() => Thread.Sleep(2000), Scheduler.NewThread); t.First(); return string.Format("Execute1 on: {0} count: {1} at: {2} thread: {3}", param, "0", DateTime.Now.ToString(), Thread.CurrentThread.ManagedThreadId.ToString()); } } ASPX page <%@ Page EnableSessionState="False" Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="RestService._Default" %> <asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent"> <script type="text/javascript"> function callMethodAsync(url, data) { $("#message").append("<br/>" + new Date()); $.ajax({ cache: false, type: "POST", async: true, url: url, data: '"de"', contentType: "application/json", dataType: "json", success: function (msg) { $("#message").append("<br/>&nbsp;&nbsp;&nbsp;" + msg); }, error: function (xhr) { alert(xhr.responseText); } }); } $(function () { $("#callMany").click(function () { $("#message").html(""); callMethodAsync("/Execute1", "hello"); callMethodAsync("/Execute2", "crazy"); callMethodAsync("/Execute3", "world"); }); }); </script> </asp:Content> <asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent"> <input type="button" id="callMany" value="Post Many" /> <div id="message"> </div> </asp:Content> Web.config (relevant) <system.webServer> <modules runAllManagedModulesForAllRequests="true" /> </system.webServer> <system.serviceModel> <serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" /> <standardEndpoints> <webHttpEndpoint> <standardEndpoint name="" helpEnabled="true" automaticFormatSelectionEnabled="true" /> </webHttpEndpoint> </standardEndpoints> </system.serviceModel> Global.asax void Application_Start(object sender, EventArgs e) { RouteTable.Routes.Ignore("{resource}.axd/{*pathInfo}"); RouteTable.Routes.Add(new ServiceRoute("", new WebServiceHostFactory(), typeof(MyService))); }

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• Java Thread execution on same data

  - by AR89

  first of all here is the code, you can just copy an paste import java.util.ArrayList; public class RepetionCounter implements Runnable{ private int x; private int y; private int[][] matrix; private int xCounter; private int yCounter; private ArrayList<Thread> threadArray; private int rowIndex; private boolean[] countCompleted; public RepetionCounter(int x, int y, int [][]matrix) { this.x = x; this.y = y; this.matrix = matrix; this.threadArray = new ArrayList<Thread>(matrix.length); this.rowIndex = 0; for(int i = 0; i < matrix.length; i++){ threadArray.add(new Thread(this)); } countCompleted = new boolean[matrix.length]; } public void start(){ for (int i = 0; i < threadArray.size(); i++){ threadArray.get(i).start(); this.rowIndex++; } } public void count(int rowIndex) { for(int i = 0; i < matrix[rowIndex].length; i++){ if (matrix[rowIndex][i] == x){ this.xCounter++; } else if (matrix[rowIndex][i] == y){ this.yCounter++; } } } @Override public void run() { count(this.rowIndex); countCompleted[this.rowIndex] = true; } public int getxCounter() { return xCounter; } public void setxCounter(int xCounter) { this.xCounter = xCounter; } public int getyCounter() { return yCounter; } public void setyCounter(int yCounter) { this.yCounter = yCounter; } public boolean[] getCountCompleted() { return countCompleted; } public void setCountCompleted(boolean[] countCompleted) { this.countCompleted = countCompleted; } public static void main(String args[]){ int[][] matrix = {{0,2,1}, {2,3,4}, {3,2,0}}; RepetionCounter rc = new RepetionCounter(0, 2, matrix); rc.start(); boolean ready = false; while(!ready){ for(int i = 0; i < matrix.length; i++){ if (rc.getCountCompleted()[i]){ ready = true; } else { ready = false; } } } if (rc.getxCounter() > rc.getyCounter()){ System.out.println("Thre are more x than y"); } else {System.out.println("There are:"+rc.getxCounter()+" x and:"+rc.getyCounter()+" y"); } } } What I want this code to do: I give to the object a matrix and tow numbers, and I want to know how much times these two numbers occurs in the matrix. I create as many thread as the number of rows of the matrix (that' why there is that ArrayList), so in this object I have k threads (supposing k is the number of rows), each of them count the occurrences of the two numbers. The problem is: if I run it for the first time everything work, but if I try to execute it another time I get and IndexOutOfBoundException, or a bad count of the occurrences, the odd thing is that if I get the error, and modify the code, after that it will works again just for once. Can you explain to me why is this happening?

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• Android GPS timeout

  - by Scott Saunders

  I'm writing an Android application that, among other things, needs to send the current GPS coordinates to a server when the user tells it to. From a context menu, I run the service below. The service is a LocationListener and requests updates from the LocationManager. When it gets a location (onLocationChanged()), it removes itself as a listener and sends the coordinates off to the server. All of this is working. However, if GPS coordinates are not quickly available, my service just keeps running until it gets some. It holds up the UI with a progress dialog, which is annoying. Worse, if the user has moved since starting the service, the first GPS coordinates might be wrong and the app will send bad data to the server. I need a timeout on the service. Is there a good way to do that? I'm not very experienced with threads. I think I can run a Runnable in the onStartCommand() method that will somehow count down 30 seconds and then, if there is no GPS result yet, call my service's stop() method. Does that sound like the best way to do this? Alternatively, is it possible to tell if the GPS cannot get a fix? How would I go about doing that? Edit: To further clarify, I'm looking for the best way to "give up" on getting a Location after some amount of time. public class AddCurrentLocation extends Service implements LocationListener { Application app; LocationManager mLocManager; ProgressDialog mDialog; @Override public int onStartCommand(Intent intent, int arg0, int arg1) { app = getApplication(); // show progress dialog if (app.getScreen() != null) { mDialog = ProgressDialog.show(app.getScreen(), "", "Adding Location. Please wait...", true); } // find GPS service and start listening Criteria criteria = new Criteria(); criteria.setAccuracy(Criteria.ACCURACY_FINE); mLocManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); String bestProvider = mLocManager.getBestProvider(criteria, true); mLocManager.requestLocationUpdates(bestProvider, 2000, 0, this); return START_NOT_STICKY; } private void stop() { mLocManager.removeUpdates(this); if (mDialog != null) { mDialog.dismiss(); } stopSelf(); } @Override public void onLocationChanged(Location location) { // done with GPS stop listening mLocManager.removeUpdates(this); sendLocation(location); // method to send info to server stop(); } // other required methods and sendLocation() ... }

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• Android threading and database locking

  - by Sena Gbeckor-Kove

  Hi, We are using AsyncTasks to access database tables and cursors. Unfortunately we are seeing occasional exceptions regarding the database being locked. E/SQLiteOpenHelper(15963): Couldn't open iviewnews.db for writing (will try read-only): E/SQLiteOpenHelper(15963): android.database.sqlite.SQLiteException: database is locked E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteDatabase.native_setLocale(Native Method) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteDatabase.setLocale(SQLiteDatabase.java:1637) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1587) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:638) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:659) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:652) E/SQLiteOpenHelper(15963): at android.app.ApplicationContext.openOrCreateDatabase(ApplicationContext.java:482) E/SQLiteOpenHelper(15963): at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:193) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:98) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:158) E/SQLiteOpenHelper(15963): at com.iview.android.widget.IViewNewsTopStoryWidget.initData(IViewNewsTopStoryWidget.java:73) E/SQLiteOpenHelper(15963): at com.iview.android.widget.IViewNewsTopStoryWidget.updateNewsWidgets(IViewNewsTopStoryWidget.java:121) E/SQLiteOpenHelper(15963): at com.iview.android.async.GetNewsTask.doInBackground(GetNewsTask.java:338) E/SQLiteOpenHelper(15963): at com.iview.android.async.GetNewsTask.doInBackground(GetNewsTask.java:1) E/SQLiteOpenHelper(15963): at android.os.AsyncTask$2.call(AsyncTask.java:185) E/SQLiteOpenHelper(15963): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:256) E/SQLiteOpenHelper(15963): at java.util.concurrent.FutureTask.run(FutureTask.java:122) E/SQLiteOpenHelper(15963): at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:648) E/SQLiteOpenHelper(15963): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:673) E/SQLiteOpenHelper(15963): at java.lang.Thread.run(Thread.java:1060) Does anybody have a general example for code which writes to a database from a different thread than the one reading and how can we ensure thread safety. One suggestion I've had is to use a ContentProvider, as this would handle the access of the database from multiple threads. I am going to look at this, but is this the recommended method of handling such a problem? It seems rather heavyweight considering we're talking about in front or behind Thanks in advance.

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• Python Socket Getting Connection Reset

  - by Ian

  I created a threaded socket listener that stores newly accepted connections in a queue. The socket threads then read from the queue and respond. For some reason, when doing benchmarking with 'ab' (apache benchmark) using a concurrency of 2 or more, I always get a connection reset before it's able to complete the benchmark (this is taking place locally, so there's no external connection issue). class server: _ip = '' _port = 8888 def __init__(self, ip=None, port=None): if ip is not None: self._ip = ip if port is not None: self._port = port self.server_listener(self._ip, self._port) def now(self): return time.ctime(time.time()) def http_responder(self, conn, addr): httpobj = http_builder() httpobj.header('HTTP/1.1 200 OK') httpobj.header('Content-Type: text/html; charset=UTF-8') httpobj.header('Connection: close') httpobj.body("Everything looks good") data = httpobj.generate() sent = conn.sendall(data) def http_thread(self, id): self.log("THREAD %d: Starting Up..." % id) while True: conn, addr = self.q.get() ip, port = addr self.log("THREAD %d: responding to request: %s:%s - %s" % (id, ip, port, self.now())) self.http_responder(conn, addr) self.q.task_done() conn.close() def server_listener(self, host, port): self.q = Queue.Queue(0) sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.bind( (host, port) ) sock.listen(5) for i in xrange(4): #thread count thread.start_new(self.http_thread, (i+1, )) while True: self.q.put(sock.accept()) sock.close() server('', 9999) When running the benchmark, I get totally random numbers of good requests before it errors out, usually between 4 and 500. Edit: Took me a while to figure it out, but the problem was in sock.listen(5). Because I was using apache benchmark with a higher concurrency (5 and up) it was causing the backlog of connections to pile up, at which point the connections started getting dropped by the socket.

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• Atomic Instructions and Variable Update visibility

  - by dsimcha

  On most common platforms (the most important being x86; I understand that some platforms have extremely difficult memory models that provide almost no guarantees useful for multithreading, but I don't care about rare counter-examples), is the following code safe? Thread 1: someVariable = doStuff(); atomicSet(stuffDoneFlag, 1); Thread 2: while(!atomicRead(stuffDoneFlag)) {} // Wait for stuffDoneFlag to be set. doMoreStuff(someVariable); Assuming standard, reasonable implementations of atomic ops: Is Thread 1's assignment to someVariable guaranteed to complete before atomicSet() is called? Is Thread 2 guaranteed to see the assignment to someVariable before calling doMoreStuff() provided it reads stuffDoneFlag atomically? Edits: The implementation of atomic ops I'm using contains the x86 LOCK instruction in each operation, if that helps. Assume stuffDoneFlag is properly cleared somehow. How isn't important. This is a very simplified example. I created it this way so that you wouldn't have to understand the whole context of the problem to answer it. I know it's not efficient.

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• synchronizing reads to a java collection

  - by jeff

  so i want to have an arraylist that stores a series of stock quotes. but i keep track of bid price, ask price and last price for each. of course at any time, the bid ask or last of a given stock can change. i have one thread that updates the prices and one that reads them. i want to make sure that when reading no other thread is updating a price. so i looked at synchronized collection. but that seems to only prevent reading while another thread is adding or deleting an entry to the arraylist. so now i'm onto the wrapper approach: public class Qte_List { private final ArrayList<Qte> the_list; public void UpdateBid(String p_sym, double p_bid){ synchronized (the_list){ Qte q = Qte.FindBySym(the_list, p_sym); q.bid=p_bid;} } public double ReadBid(String p_sym){ synchronized (the_list){ Qte q = Qte.FindBySym(the_list, p_sym); return q.bid;} } so what i want to accomplish with this is only one thread can be doing anything - reading or updating an the_list's contents - at one time. am i approach this right? thanks.

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• Display archived emails in inbox thread? (Gmail + Thunderbird 3.1)

  - by AndyL

  A features that I liked in GMail was that when an email arrived that was a reply to an earlier email, Gmail would display all of the previous emails along with the new one in a single thread in my inbox. Importantly, GMail would display emails in the thread even if they had been previously archived. Now I am using Thunderbird to access GMail. Thunderbird 3.1 supports Gmail-style archiving and threads, but it only dispalys messages in threads if they are in the same folder. If I have an email thread with someone and I archive that thread and then a new message arrives, only the new message appears in my inbox. This is really inconvenient. Before I could archive a thread without worrying that I would lose the contents of the thread should a new email arrive. Now, if an email arrives I must go through the All Mail box and find the rest of the thread. Is there any way to set Thunderbird so that it will automatically show the archived emails in the thread along with the new one? Perhaps there is some way to automatically un-archive the rest of the messages? Maybe this is an add-on waiting to be written?

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• Using CURL within a loop to download a file, 1st one works, 2nd one times out

  - by kitenski

  Morning all, I am using CURL to download an image file within a loop. The first time it runs fine and I see the image appear in the directory. The second time it fails with a timeout, despite it being a valid URL. Can anyone suggest why it always fails on the 2nd time and how to fix it? The snippet of code is: // download image $extension = "gif"; $ch = curl_init(); curl_setopt($ch, CURLOPT_TIMEOUT, 90); curl_setopt($ch, CURLOPT_URL, $imgurl); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true); echo $imgurl . " attempting to open URL "; $i = curl_exec($ch); if ( $i==false ) { echo curl_errno($ch).' '.curl_error($ch); } $image_name=time().'.'.$extension; $f = fopen('/fulldirectorypath/' . $image_name ,'w+'); fwrite($f,$i); fclose($f); I have put an echo in there to display the $IMGURL, to check it is valid, and upped the timeout to 90 secs, but it still fails. This is what I see on screen: http://images.eu-xmedia.de/thumbnails/34555861/5676051/pt=pic,lang=2,origfile=yes/image.gif attempting to open URL 28 Operation timed out after 90 seconds with 0 bytes received an empty file is created in my directory. thanks alot, Greg

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• Python's asyncore to periodically send data using a variable timeout. Is there a better way?

  - by Nick Sonneveld

  I wanted to write a server that a client could connect to and receive periodic updates without having to poll. The problem I have experienced with asyncore is that if you do not return true when dispatcher.writable() is called, you have to wait until after the asyncore.loop has timed out (default is 30s). The two ways I have tried to work around this is 1) reduce timeout to a low value or 2) query connections for when they will next update and generate an adequate timeout value. However if you refer to 'Select Law' in 'man 2 select_tut', it states, "You should always try to use select() without a timeout." Is there a better way to do this? Twisted maybe? I wanted to try and avoid extra threads. I'll include the variable timeout example here: #!/usr/bin/python import time import socket import asyncore # in seconds UPDATE_PERIOD = 4.0 class Channel(asyncore.dispatcher): def __init__(self, sock, sck_map): asyncore.dispatcher.__init__(self, sock=sock, map=sck_map) self.last_update = 0.0 # should update immediately self.send_buf = '' self.recv_buf = '' def writable(self): return len(self.send_buf) > 0 def handle_write(self): nbytes = self.send(self.send_buf) self.send_buf = self.send_buf[nbytes:] def handle_read(self): print 'read' print 'recv:', self.recv(4096) def handle_close(self): print 'close' self.close() # added for variable timeout def update(self): if time.time() >= self.next_update(): self.send_buf += 'hello %f\n'%(time.time()) self.last_update = time.time() def next_update(self): return self.last_update + UPDATE_PERIOD class Server(asyncore.dispatcher): def __init__(self, port, sck_map): asyncore.dispatcher.__init__(self, map=sck_map) self.port = port self.sck_map = sck_map self.create_socket(socket.AF_INET, socket.SOCK_STREAM) self.bind( ("", port)) self.listen(16) print "listening on port", self.port def handle_accept(self): (conn, addr) = self.accept() Channel(sock=conn, sck_map=self.sck_map) # added for variable timeout def update(self): pass def next_update(self): return None sck_map = {} server = Server(9090, sck_map) while True: next_update = time.time() + 30.0 for c in sck_map.values(): c.update() # <-- fill write buffers n = c.next_update() #print 'n:',n if n is not None: next_update = min(next_update, n) _timeout = max(0.1, next_update - time.time()) asyncore.loop(timeout=_timeout, count=1, map=sck_map)

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• NSTimer as a timeout mechanism

  - by alexantd

  I'm pretty sure this is really simple, and I'm just missing something obvious. I have an app that needs to download data from a web service for display in a UITableView, and I want to display a UIAlertView if the operation takes more than X seconds to complete. So this is what I've got (simplified for brevity): MyViewController.h @interface MyViewController : UIViewController <UITableViewDelegate, UITableViewDataSource> { NSTimer *timer; } @property (nonatomic, retain) NSTimer *timer; MyViewController.m @implementation MyViewController @synthesize timer; - (void)viewDidLoad { timer = [NSTimer scheduledTimerWithTimeInterval:20 target:self selector:@selector(initializationTimedOut:) userInfo:nil repeats:NO]; [self doSomethingThatTakesALongTime]; [timer invalidate]; } - (void)doSomethingThatTakesALongTime { sleep(30); // for testing only // web service calls etc. go here } - (void)initializationTimedOut:(NSTimer *)theTimer { // show the alert view } My problem is that I'm expecting the [self doSomethingThatTakesALongTime] call to block while the timer keeps counting, and I'm thinking that if it finishes before the timer is done counting down, it will return control of the thread to viewDidLoad where [timer invalidate] will proceed to cancel the timer. Obviously my understanding of how timers/threads work is flawed here because the way the code is written, the timer never goes off. However, if I remove the [timer invalidate], it does.

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• How to cancel a jquery.load()?

  - by Dirk Jönsson

  I'd like to cancel a .load() operation, when the load() does not return in 5 seconds. If it's so I show an error message like 'sorry, no picture loaded'. What I have is... ...the timeout handling: jQuery.fn.idle = function(time, postFunction){ var i = $(this); i.queue(function(){ setTimeout(function(){ i.dequeue(); postFunction(); }, time); }); return $(this); }; ... initializing of the error message timeout: var hasImage = false; $('#errorMessage') .idle(5000, function() { if(!hasImage) { // 1. cancel .load() // 2. show error message } }); ... the image loading: $('#myImage') .attr('src', '/url/anypath/image.png') .load(function(){ hasImage = true; // do something... }); The only thing I could not figure out is how to cancel the running load() (if it's possible). Please help. Thanks! Edit: Another way: How do I prevent the .load() method to call it's callback function when it's returning?

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• Database.ExecuteNonQuery does not return

  - by dan-waterbly

  I have a very odd issue. When I execute a specific database stored procedure from C# using SqlCommand.ExecuteNonQuery, my stored procedure is never executed. Furthermore, SQL Profiler does not register the command at all. I do not receive a command timeout, and no exeception is thrown. The weirdest thing is that this code has worked fine over 1,200,000 times, but for this one particular file I am inserting into the database, it just hangs forever. When I kill the application, I receive this error in the event log of the database server: "A fatal error occurued while reading the input stream from the network. The session will be terminated (input error: 64, output error: 0). Which makes me think that the database server is receiving the command, though SQL Profiler says otherwise. I know that the appropiate permissions are set, and that the connection string is right as this piece of code and stored procedure works fine with other files. Below is the code that calls the stored procedure, it may be important to note that the file I am trying to insert is 33.5MB, but I have added more than 10,000 files larger than 500MB, so I do not think the size is the issue: using (SqlConnection sqlconn = new SqlConnection(ConfigurationManager.ConnectionStrings["TheDatabase"].ConnectionString)) using (SqlCommand command = sqlconn.CreateCommand()) { command.CommandText = "Add_File"; command.CommandType = CommandType.StoredProcedure; command.CommandTimeout = 30 //should timeout in 30 seconds, but doesn't... command.Parameters.AddWithValue("@ID", ID).SqlDbType = SqlDbType.BigInt; command.Parameters.AddWithValue("@BinaryData", byteArr).SqlDbType = SqlDbType.VarBinary; command.Parameters.AddWithValue("@FileName", fileName).SqlDbType = SqlDbType.VarChar; sqlconn.Open(); command.ExecuteNonQuery(); } There is no firewall between the server making the call and the database server, and the windows firewalls have been disabled to troubleshoot this issue.

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• QTime or QTimer wait for timeout

  - by user968243

  I'm writting a Qt application, and I have a four hour loop (in a seperate thread). In that four hour loop, I have to: do stuff with the serial port; wait a fixed period of time; do some more stuff with the serial port; wait an arbitrary amount of time. when 500ms have past, do more stuff; Go to 1. and repeat for four hours. Currently, my method of doing this is really bad, and crashes some computers. I have a whole bunch of code, but the following snippet basically shows the problem. The CPU goes to ~100% and eventually can crash the computer. void CRelayduinoUserControl::wait(int timeMS) { int curTime = loopTimer->elapsed(); while(loopTimer->elapsed() < curTime + timeMS); } I need to somehow wait for a particular amount of time to pass before continuing on with the program. Is there some function which will just wait for some arbitrary period of time while keeping all the timers going?

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• Sd card bigger than 2gb is not recognized in ubuntu 12.04

  - by dex1

  When I insert a card up to 2gb it is immediately seen by the system but if try it with bigger one it's not seen. I presume the issue is not due to the card reader itself as it reads all cards under windows 7 but due to linux driver. I could see some people having similar issues but no solution. Any help appreciated. GParted doesnt see cards bigger than 2gb. After insertion small card ubuntu@ubuntu:~$ dmesg [10169.384481] mmc0: new SD card at address a95c [10169.384870] mmcblk0: mmc0:a95c SD016 14.0 MiB [10169.386715] mmcblk0: p1 everything worked fine then I removed the small one and put 8gb, waited for 2min [10295.736422] mmc0: card a95c removed [10362.448383] sdhci: Switching to 1.8V signalling voltage failed, retrying with S18R set to 0 [10372.480076] mmc0: Timeout waiting for hardware interrupt. [10382.496146] mmc0: Timeout waiting for hardware interrupt. [10392.512149] mmc0: Timeout waiting for hardware interrupt. [10402.528145] mmc0: Timeout waiting for hardware interrupt. [10402.529267] mmc0: error -110 whilst initialising SD card [10402.748807] sdhci: Switching to 1.8V signalling voltage failed, retrying with S18R set to 0 [10412.768063] mmc0: Timeout waiting for hardware interrupt. [10422.784051] mmc0: Timeout waiting for hardware interrupt. [10432.800076] mmc0: Timeout waiting for hardware interrupt. [10442.816067] mmc0: Timeout waiting for hardware interrupt. [10442.817165] mmc0: error -110 whilst initialising SD card [10443.040805] sdhci: Switching to 1.8V signalling voltage failed, retrying with S18R set to 0 [10453.056145] mmc0: Timeout waiting for hardware interrupt. [10463.072139] mmc0: Timeout waiting for hardware interrupt. [10473.088050] mmc0: Timeout waiting for hardware interrupt. [10483.104046] mmc0: Timeout waiting for hardware interrupt. [10483.104107] mmc0: error -110 whilst initialising SD card [10483.328960] sdhci: Switching to 1.8V signalling voltage failed, retrying with S18R set to 0 [10493.344144] mmc0: Timeout waiting for hardware interrupt. ubuntu@ubuntu:~$ lspci 00:00.0 Host bridge: Intel Corporation Mobile PM965/GM965/GL960 Memory Controller Hub (rev 03) 00:02.0 VGA compatible controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (primary) (rev 03) 00:02.1 Display controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (secondary) (rev 03) 00:1a.0 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #4 (rev 03) 00:1a.1 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #5 (rev 03) 00:1a.7 USB controller: Intel Corporation 82801H (ICH8 Family) USB2 EHCI Controller #2 (rev 03) 00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio Controller (rev 03) 00:1c.0 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 1 (rev 03) 00:1c.3 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 4 (rev 03) 00:1c.4 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 5 (rev 03) 00:1c.5 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 6 (rev 03) 00:1d.0 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #1 (rev 03) 00:1d.1 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #2 (rev 03) 00:1d.2 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #3 (rev 03) 00:1d.7 USB controller: Intel Corporation 82801H (ICH8 Family) USB2 EHCI Controller #1 (rev 03) 00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev f3) 00:1f.0 ISA bridge: Intel Corporation 82801HM (ICH8M) LPC Interface Controller (rev 03) 00:1f.1 IDE interface: Intel Corporation 82801HM/HEM (ICH8M/ICH8M-E) IDE Controller (rev 03) 00:1f.2 SATA controller: Intel Corporation 82801HM/HEM (ICH8M/ICH8M-E) SATA Controller [AHCI mode] (rev 03) 00:1f.3 SMBus: Intel Corporation 82801H (ICH8 Family) SMBus Controller (rev 03) 07:00.0 Ethernet controller: Marvell Technology Group Ltd. 88E8072 PCI-E Gigabit Ethernet Controller (rev 16) 0a:01.0 FireWire (IEEE 1394): O2 Micro, Inc. Firewire (IEEE 1394) (rev 02) 0a:01.2 SD Host controller: O2 Micro, Inc. Integrated MMC/SD Controller (rev 02) 0a:01.3 Mass storage controller: O2 Micro, Inc. Integrated MS/xD Controller (rev 01) Same cards, same machine (same reader) only different OS(win7) work flawlessly. Some interesting reading I came across but is Chinese for me http://www.mail-archive.com/[email protected]/msg14598.html and another bit http://article.gmane.org/gmane.linux.kernel.mmc/11973/match=sd+card+not+recognized

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• Cannot connect to MySQL with JDBC - Connection Timeout - Ubuntu 9.04

  - by gav

  I am running Ubuntu and am ultimately trying to connect Tomcat to my MySQL database using JDBC. It has worked previously but after a reboot the instance now fails to connect. Both Tomcat 6 and MySQL 5.0.75 are on the same machine Connection string: jdbc:mysql:///localhost:3306 I can connect to MySQL on the command line using the mysql command The my.cnf file is pretty standard (Available on request) has bind address: 127.0.0.1 I cannot Telnet to the MySQL port despite netstat saying MySQL is listening I have one IpTables rule to forward 80 - 8080 and no firewall I'm aware of. I'm pretty new to this and I'm not sure what else to test. I don't know whether I should be looking in etc/interfaces and if I did what to look for. It's weird because it used to work but after a reboot it's down so I must have changed something.... :). I realise a timeout indicates the server is not responding and I assume it's because the request isn't actually getting through. I installed MySQL via apt-get and Tomcat manually. MySqld processes root@88:/var/log/mysql# ps -ef | grep mysqld root 21753 1 0 May27 ? 00:00:00 /bin/sh /usr/bin/mysqld_safe mysql 21792 21753 0 May27 ? 00:00:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=/var/run/mysqld/mysqld.pid --skip-external-locking --port=3306 --socket=/var/run/mysqld/mysqld.sock root 21793 21753 0 May27 ? 00:00:00 logger -p daemon.err -t mysqld_safe -i -t mysqld root 21888 13676 0 11:23 pts/1 00:00:00 grep mysqld Netstat root@88:/var/log/mysql# netstat -lnp | grep mysql tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN 21792/mysqld unix 2 [ ACC ] STREAM LISTENING 1926205077 21792/mysqld /var/run/mysqld/mysqld.sock Toy Connection Class root@88:~# cat TestConnect/TestConnection.java import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; public class TestConnection { public static void main(String args[]) throws Exception { Connection con = null; try { Class.forName("com.mysql.jdbc.Driver").newInstance(); System.out.println("Got driver"); con = DriverManager.getConnection( "jdbc:mysql:///localhost:3306", "uname", "pass"); System.out.println("Got connection"); if(!con.isClosed()) System.out.println("Successfully connected to " + "MySQL server using TCP/IP..."); } finally { if(con != null) con.close(); } } } Toy Connection Class Output Note: This is the same error I get from Tomcat. root@88:~/TestConnect# java -cp mysql-connector-java-5.1.12-bin.jar:. TestConnection Got driver Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure The last packet sent successfully to the server was 1 milliseconds ago. The driver has not received any packets from the server. at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at com.mysql.jdbc.Util.handleNewInstance(Util.java:409) at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1122) at TestConnection.main(TestConnection.java:14) Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at com.mysql.jdbc.Util.handleNewInstance(Util.java:409) at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1122) at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:344) at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2181) ... 12 more Caused by: java.net.ConnectException: Connection timed out at java.net.PlainSocketImpl.socketConnect(Native Method) ... 13 more Telnet Output root@88:~/TestConnect# telnet localhost 3306 Trying 127.0.0.1... telnet: Unable to connect to remote host: Connection timed out

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• Database connection timeout

  - by Clinton Bosch

  Hi I have read so many articles on the Internet about this problem but none seem to have a clear solution. Please could someone give me a definite answer as to why I am getting database timeouts. The app is a GWT app that is being hosted on a Tomcat 5.5 server. I use spring and the session factory is created in the applicationContext.xml as follows <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">${connection.dialect}</prop> <prop key="hibernate.connection.username">${connection.username}</prop> <prop key="hibernate.connection.password">${connection.password}</prop> <prop key="hibernate.connection.url">${connection.url}</prop> <prop key="hibernate.connection.driver_class">${connection.driver.class}</prop> <prop key="hibernate.show_sql">${show.sql}</prop> <prop key="hibernate.hbm2ddl.auto">update</prop> <prop key="hibernate.c3p0.min_size">5</prop> <prop key="hibernate.c3p0.max_size">20</prop> <prop key="hibernate.c3p0.timeout">1800</prop> <prop key="hibernate.c3p0.max_statements">50</prop> <prop key="hibernate.c3p0.idle_test_period">300</prop> </props> </property> <property name="annotatedClasses"> <list> <value>za.co.xxxx.traintrack.server.model.Answer</value> <value>za.co.xxxx.traintrack.server.model.Company</value> <value>za.co.xxxx.traintrack.server.model.CompanyRegion</value> <value>za.co.xxxx.traintrack.server.model.Merchant</value> <value>za.co.xxxx.traintrack.server.model.Module</value> <value>za.co.xxxx.traintrack.server.model.Question</value> <value>za.co.xxxx.traintrack.server.model.User</value> <value>za.co.xxxx.traintrack.server.model.CompletedModule</value> </list> </property> </bean> <bean id="dao" class="za.co.xxxx.traintrack.server.DAO"> <property name="sessionFactory" ref="sessionFactory"/> <property name="adminUsername" value="${admin.user.name}"/> <property name="adminPassword" value="${admin.user.password}"/> <property name="godUsername" value="${god.user.name}"/> <property name="godPassword" value="${god.user.password}"/> </bean> All works fine untile the next day: INFO | jvm 1 | 2010/06/15 14:42:27 | 2010-06-15 18:42:27,804 WARN [JDBCExceptionReporter] : SQL Error: 0, SQLState: 08S01 INFO | jvm 1 | 2010/06/15 14:42:27 | 2010-06-15 18:42:27,821 ERROR [JDBCExceptionReporter] : The last packet successfully received from the server was 38729 seconds ago.The last packet sent successfully to the server was 38729 seconds ago, which is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem. INFO | jvm 1 | 2010/06/15 14:42:27 | Jun 15, 2010 6:42:27 PM org.apache.catalina.core.ApplicationContext log INFO | jvm 1 | 2010/06/15 14:42:27 | SEVERE: Exception while dispatching incoming RPC call I have read so many different things (none of which worked), please help

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• Can't figure out where race condition is occuring

  - by Nik

  I'm using Valgrind --tool=drd to check my application that uses Boost::thread. Basically, the application populates a set of "Book" values with "Kehai" values based on inputs through a socket connection. On a seperate thread, a user can connect and get the books send to them. Its fairly simple, so i figured using a boost::mutex::scoped_lock on the location that serializes the book and the location that clears out the book data should be suffice to prevent any race conditions. Here is the code: void Book::clear() { boost::mutex::scoped_lock lock(dataMutex); for(int i =NUM_KEHAI-1; i >= 0; --i) { bid[i].clear(); ask[i].clear(); } } int Book::copyChangedKehaiToString(char* dst) const { boost::mutex::scoped_lock lock(dataMutex); sprintf(dst, "%-4s%-13s",market.c_str(),meigara.c_str()); int loc = 17; for(int i = 0; i < Book::NUM_KEHAI; ++i) { if(ask[i].changed > 0) { sprintf(dst+loc,"A%i%-21s%-21s%-21s%-8s%-4s",i,ask[i].price.c_str(),ask[i].volume.c_str(),ask[i].number.c_str(),ask[i].postTime.c_str(),ask[i].status.c_str()); loc += 77; } } for(int i = 0; i < Book::NUM_KEHAI; ++i) { if(bid[i].changed > 0) { sprintf(dst+loc,"B%i%-21s%-21s%-21s%-8s%-4s",i,bid[i].price.c_str(),bid[i].volume.c_str(),bid[i].number.c_str(),bid[i].postTime.c_str(),bid[i].status.c_str()); loc += 77; } } return loc; } The clear() function and the copyChangedKehaiToString() function are called in the datagetting thread and data sending thread,respectively. Also, as a note, the class Book: struct Book { private: Book(const Book&); Book& operator=(const Book&); public: static const int NUM_KEHAI=10; struct Kehai; friend struct Book::Kehai; struct Kehai { private: Kehai& operator=(const Kehai&); public: std::string price; std::string volume; std::string number; std::string postTime; std::string status; int changed; Kehai(); void copyFrom(const Kehai& other); Kehai(const Kehai& other); inline void clear() { price.assign(""); volume.assign(""); number.assign(""); postTime.assign(""); status.assign(""); changed = -1; } }; std::vector<Kehai> bid; std::vector<Kehai> ask; tm recTime; mutable boost::mutex dataMutex; Book(); void clear(); int copyChangedKehaiToString(char * dst) const; }; When using valgrind --tool=drd, i get race condition errors such as the one below: ==26330== Conflicting store by thread 1 at 0x0658fbb0 size 4 ==26330== at 0x653AE68: std::string::_M_mutate(unsigned int, unsigned int, unsigned int) (in /usr/lib/libstdc++.so.6.0.8) ==26330== by 0x653AFC9: std::string::_M_replace_safe(unsigned int, unsigned int, char const*, unsigned int) (in /usr/lib/libstdc++.so.6.0.8) ==26330== by 0x653B064: std::string::assign(char const*, unsigned int) (in /usr/lib/libstdc++.so.6.0.8) ==26330== by 0x653B134: std::string::assign(char const*) (in /usr/lib/libstdc++.so.6.0.8) ==26330== by 0x8055D64: Book::Kehai::clear() (Book.h:50) ==26330== by 0x8094A29: Book::clear() (Book.cpp:78) ==26330== by 0x808537E: RealKernel::start() (RealKernel.cpp:86) ==26330== by 0x804D15A: main (main.cpp:164) ==26330== Allocation context: BSS section of /usr/lib/libstdc++.so.6.0.8 ==26330== Other segment start (thread 2) ==26330== at 0x400BB59: pthread_mutex_unlock (drd_pthread_intercepts.c:633) ==26330== by 0xC59565: pthread_mutex_unlock (in /lib/libc-2.5.so) ==26330== by 0x805477C: boost::mutex::unlock() (mutex.hpp:56) ==26330== by 0x80547C9: boost::unique_lock<boost::mutex>::~unique_lock() (locks.hpp:340) ==26330== by 0x80949BA: Book::copyChangedKehaiToString(char*) const (Book.cpp:134) ==26330== by 0x80937EE: BookSerializer::serializeBook(Book const&, std::string const&) (BookSerializer.cpp:41) ==26330== by 0x8092D05: BookSnapshotManager::getSnaphotDataList() (BookSnapshotManager.cpp:72) ==26330== by 0x8088179: SnapshotServer::getDataList() (SnapshotServer.cpp:246) ==26330== by 0x808870F: SnapshotServer::run() (SnapshotServer.cpp:183) ==26330== by 0x808BAF5: boost::_mfi::mf0<void, RealThread>::operator()(RealThread*) const (mem_fn_template.hpp:49) ==26330== by 0x808BB4D: void boost::_bi::list1<boost::_bi::value<RealThread*> >::operator()<boost::_mfi::mf0<void, RealThread>, boost::_bi::list0>(boost::_bi::type<void>, boost::_mfi::mf0<void, RealThread>&, boost::_bi::list0&, int) (bind.hpp:253) ==26330== by 0x808BB90: boost::_bi::bind_t<void, boost::_mfi::mf0<void, RealThread>, boost::_bi::list1<boost::_bi::value<RealThread*> > >::operator()() (bind_template.hpp:20) ==26330== Other segment end (thread 2) ==26330== at 0x400B62A: pthread_mutex_lock (drd_pthread_intercepts.c:580) ==26330== by 0xC59535: pthread_mutex_lock (in /lib/libc-2.5.so) ==26330== by 0x80546B8: boost::mutex::lock() (mutex.hpp:51) ==26330== by 0x805473B: boost::unique_lock<boost::mutex>::lock() (locks.hpp:349) ==26330== by 0x8054769: boost::unique_lock<boost::mutex>::unique_lock(boost::mutex&) (locks.hpp:227) ==26330== by 0x8094711: Book::copyChangedKehaiToString(char*) const (Book.cpp:113) ==26330== by 0x80937EE: BookSerializer::serializeBook(Book const&, std::string const&) (BookSerializer.cpp:41) ==26330== by 0x808870F: SnapshotServer::run() (SnapshotServer.cpp:183) ==26330== by 0x808BAF5: boost::_mfi::mf0<void, RealThread>::operator()(RealThread*) const (mem_fn_template.hpp:49) ==26330== by 0x808BB4D: void boost::_bi::list1<boost::_bi::value<RealThread*> >::operator()<boost::_mfi::mf0<void, RealThread>, boost::_bi::list0>(boost::_bi::type<void>, boost::_mfi::mf0<void, RealThread>&, boost::_bi::list0&, int) (bind.hpp:253) For the life of me, i can't figure out where the race condition is. As far as I can tell, clearing the kehai is done only after having taken the mutex, and the same holds true with copying it to a string. Does anyone have any ideas what could be causing this, or where I should look? Thank you kindly.

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