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• Moving delegate-related function to a different thread

  - by Chris

  Hello everybody. We are developing a library in C# that communicates with the serial port. We have a function that is given to a delegate. The problem is that we want it to be run in a different thread. We tried creating a new thread (called DatafromBot) but keep using it as follows (first line): comPort.DataReceived += new SerialDataReceivedEventHandler(comPort_DataReceived); DatafromBot = new Thread(comPort_DataReceived); DatafromBot.Start(); comPort_DataReceived is defined as: Thread DatafromBot; public void comPort_DataReceived(object sender, SerialDataReceivedEventArgs e) { ... } The following errors occur: Error 3 The best overloaded method match for 'System.Threading.Thread.Thread(System.Threading.ThreadStart)' has some invalid arguments C:...\IR52cLow\CommunicationManager.cs 180 27 IR52cLow Error 4 Argument '1': cannot convert from 'method group' to 'System.Threading.ThreadStart' C:...\IR52cLow\CommunicationManager.cs 180 38 IR52cLow Any ideas of how we should convert this to get it to compile? Please note that comPort.DataReceived (pay attention to "." instead of "_") lies within a system library and cannot be modified. Thanks for your time! Chris

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• Is NSPasteboard thread-safe?

  - by Joe

  Is it safe to write data to an NSPasteboard object from a background thread? I can't seem to find a definitive answer anywhere. I think the assumption is that the data will be written to the pasteboard before the drag begins. Background: I have an application that is fetching data from Evernote. When the application first loads, it gets the meta data for each note, but not the note content. The note stubs are then listed in an outline view. When the user starts to drag a note, the notes are passed to the background thread that handles getting the note content from Evernote. Having the main thread block until the data is gotten results in a significant delay and a poor user experience, so I have the [outlineView:writeItems:toPasteboard:] function return YES while the background thread processes the data and invokes the main thread to write the data to the pasteboard object. If the note content gets transferred before the user drops the note somewhere, everything works perfectly. If the user drops the note somewhere before the data has been processed... well, everything blocks forever. Is it safe to just have the background thread write the data to the pasteboard?

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• Static variables and long running thread on IIS 7.5

  - by Dmitry

  Hello people. Help me solve next problem. I have ASP .NET MVC2 application. I run it on IIS 7.5. In one page user clicks button and handler for this button sends request to server (jquery.ajax). At server action in controller starts new thread (it makes long time import): var thread = new Thread(RefreshCitiesInDatabase); thread.Start(); State of import is available in static variable. New thread changes value of variable in the begin of work. User can check state of import too with the help of this variable, which is used in view. And user sees import's state. When I start this function few minutes everything is okey. On page I see right state of import, quantity of imported records is changed, I see changes in logs. But after few minutes begin troubles. When I refresh page with import state sometimes I see that import is okey but sometimes I see page with default values about import (like application is just started), but after that again I can see page with normal import's state. I tried to attach Visual Studio to IIS process and debug application. But when request comes to controller sometimes static variables have right values and sometimes they have default values (static int has 0, static string has "" etc.). Tell me what I do wrong. May be I must start additional thread in other way? Thanks in advance, Dmitry

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• How to know if all the Thread Pool's thread are already done with its tasks?

  - by mcxiand

  I have this application that will recurse all folders in a given directory and look for PDF. If a PDF file is found, the application will count its pages using ITextSharp. I did this by using a thread to recursively scan all the folders for pdf, then if then PDF is found, this will be queued to the thread pool. The code looks like this: //spawn a thread to handle the processing of pdf on each folder. var th = new Thread(() => { pdfDirectories = Directory.GetDirectories(pdfPath); processDir(pdfDirectories); }); th.Start(); private void processDir(string[] dirs) { foreach (var dir in dirs) { pdfFiles = Directory.GetFiles(dir, "*.pdf"); processFiles(pdfFiles); string[] newdir = Directory.GetDirectories(dir); processDir(newdir); } } private void processFiles(string[] files) { foreach (var pdf in files) { ThreadPoolHelper.QueueUserWorkItem( new { path = pdf }, (data) => { processPDF(data.path); } ); } } My problem is, how do i know that the thread pool's thread has finished processing all the queued items so i can tell the user that the application is done with its intended task?

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• c++ multithread

  - by chnet

  I use c++ to implement a thread class. The code is in the following. I initialize two objects, wish it will start two threads (I use pthread_self() to look the thread Id). But the result shows that there is only one thread beside the main thread. I am a bit confused... class Thread { public: int mask; pthread_t thread; Thread( int ); void start(); static void * EntryPoint (void *); void Run(); }; Thread::Thread( int a) { mask =a; } void Thread::Run() { cout<<"thread begin to run" <<endl; cout <<" Thread Id is: "<< pthread_self() << endl; // the same thread Id. } void * Thread::EntryPoint(void * pthis) { cout << "entry" <<endl; Thread *pt = (Thread *) pthis; pt->Run(); } void Thread::start() { pthread_create(&thread, NULL, EntryPoint, (void *)ThreadId ); pthread_join(thread, NULL); } int main() { int input_array[8]={3,1,2,5,6,8,7,4}; Thread t1(1); Thread t2(2); t1.start(); t2.start() }

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• c++ multithread

  - by chnet

  I use C++ to implement a thread class. My code shows in the following. I have a problem about how to access thread data. In the class Thread, I create a thread use pthread_create() function. then it calls EntryPoint() function to start thread created. In the Run function, I want to access the mask variable, it always shows segment fault. So, my question is whether the new created thread copy the data in original class? How to access the thread own data? class Thread { public: int mask; pthread_t thread; Thread( int ); void start(); static void * EntryPoint (void *); void Run(); }; Thread::Thread( int a) { mask =a; } void Thread::Run() { cout<<"thread begin to run" <<endl; cout << mask <<endl; // it always show segmentfault here } void * Thread::EntryPoint(void * pthis) { cout << "entry" <<endl; Thread *pt = (Thread *) pthis; pt->Run(); } void Thread::start() { pthread_create(&thread, NULL, EntryPoint, (void *)ThreadId ); pthread_join(thread, NULL); } int main() { int input_array[8]={3,1,2,5,6,8,7,4}; Thread t1(1); t1.start(); }

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• Determine if the current thread has low I/O priority

  - by Magnus Hoff

  I have a background thread that does some I/O-intensive background type work. To please the other threads and processes running, I set the thread priority to "background mode" using SetThreadPriority, like this: SetThreadPriority(GetCurrentThread(), THREAD_MODE_BACKGROUND_BEGIN); However, THREAD_MODE_BACKGROUND_BEGIN is only available in Windows Server 2008 or newer, as well as Windows Vista and newer, but the program needs to work well on Windows Server 2003 and XP as well. So the real code is more like this: if (!SetThreadPriority(GetCurrentThread(), THREAD_MODE_BACKGROUND_BEGIN)) { SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_LOWEST); } The problem with this is that on Windows XP it will totally disrupt the system by using too much I/O. I have a plan for a ugly and shameful way of mitigating this problem, but that depends on me being able to determine if the current thread has low I/O priority or not. Now, I know I can store which thread priority I ended up setting, but the control flow in the program is not really well suited for this. I would rather like to be able to test later whether or not the current thread has low I/O priority -- if it is in "background mode". GetThreadPriority does not seem to give me this information. Is there any way to determine if the current thread has low I/O priority?

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• Disposing ActiveX resources owned by another thread

  - by Stefan Teitge

  I've got a problem problem with threading and disposing resources. I've got a C# Windows Forms application which runs expensive operation in a thread. This thread instantiates an ActiveX control (AxControl). This control must be disposed as it uses a high amount of memory. So I implemented a Dispose() method and even a destructor. After the thread ends the destructor is called. This is sadly called by the UI thread. So invoking activexControl.Dispose(); fails with the message "COM object that has been separated from its underlying RCW", as the object belongs to another thread. How to do this correctly or is it just a bad design I use? (I stripped the code down to the minimum including removing any safety concerns.) class Program { [STAThread] static void Main() { // do stuff here, e.g. open a form new Thread(new ThreadStart(RunStuff); // do more stuff } private void RunStuff() { DoStuff stuff = new DoStuff(); stuff.PerformStuff(); } } class DoStuff : IDisposable { private AxControl activexControl; DoStuff() { activexControl = new AxControl(); activexControl.CreateControl(); // force instance } ~DoStuff() { Dispose(); } public void Dispose() { activexControl.Dispose(); } public void PerformStuff() { // invent perpetuum mobile here, takes time } }

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• Why do InterruptedExceptions clear a thread's interrupted status?

  - by Hanno Fietz

  If a thread is interrupted while inside Object.wait() or Thread.join(), it throws an InterruptedException, which resets the thread's interrupted status. I. e., if I have a loop like this inside a Runnable.run(): while (!this._workerThread.isInterrupted()) { // do something try { synchronized (this) { this.wait(this._waitPeriod); } } catch (InterruptedException e) { if (!this._isStopping()) { this._handleFault(e); } } } the thread will continue to run after calling interrupt(). This means I have to explicitly break out of the loop by checking for my own stop flag in the loop condition, rethrow the exception, or add a break. Now, this is not exactly a problem, since this behaviour is well documented and doesn't prevent me from doing anything the way I want. However, I don't seem to understand the concept behind it: Why is a thread not considered interrupted anymore once the exception has been thrown? A similar behaviour also occurs if you get the interrupted status with interrupted() instead of isInterrupted(), then, too, the thread will only appear interrupted once. Am I doing something unusual here? For example, is it more common to catch the InterruptedException outside the loop? (Even though I'm not exactly a beginner, I tagged this "beginner", because it seems like a very basic question to me, looking at it.)

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• how to call the method in thread with aruguments and return some value

  - by ratty

  i like to call the method in thread with aruguments and return some value here example class Program { static void Main() { Stopwatch stop = new Stopwatch(); stop.Start(); Thread FirstThread = new Thread(new ThreadStart(Fun1)); Thread SecondThread = new Thread(new ThreadStart(Fun2)); FirstThread.Start(); SecondThread.Start(); } public static void Fun1() { for (int i = 1; i <= 1000; i++) { Console.WriteLine("Fun1 writes:{0}", i); } } public static void Fun2() { for (int i = 1000; i >= 6; i--) { Console.WriteLine("Fun2 writes:{0}", i); } } } i know this above example run successfully but if method fun1 like this public int fun1(int i) { for (int n = i; n >= i+10; n++) { Console.WriteLine("Fun2 writes:{0}", i); } } then how can i call this in thread. Is it possible .Any body Help for me

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• Call event from original thread ??

  - by user311883

  Hi all, Here is my problem, I have a class which have a object who throw an event and in this event I throw a custom event from my class. But unfortunately the original object throw the event from another thread and so my event is also throw on another thread. This cause a exception when my custom event try to access from controls. Here is a code sample to better understand : class MyClass { // Original object private OriginalObject myObject; // My event public delegate void StatsUpdatedDelegate(object sender, StatsArgs args); public event StatsUpdatedDelegate StatsUpdated; public MyClass() { // Original object event myObject.AnEvent += new EventHandler(myObject_AnEvent); } // This event is called on another thread private void myObject_AnEvent(object sender, EventArgs e) { // Throw my custom event here StatsArgs args = new StatsArgs(..........); StatsUpdated(this, args); } } So when on my windows form I call try to update a control from the event StatsUpdated I get a cross thread exception cause it has been called on another thread. What I want to do is throw my custom event on the original class thread, so control can be used within it. Anyone can help me ?

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• How to end a thread in perl

  - by user1672190

  I am new to perl and i have a question about perl thread. I am trying to create a new thread to check if the running function is timed out, and my way of doing it is as below. Logic is 1.create a new thread 2.run the main function and see if it is timed out, if ture, kill it Sample code: $exit_tread = false; # a flag to make sure timeout thread will run my $thr_timeout = threads->new( \&timeout ); execute main function here; $exit_thread = true # set the flag to true to force thread ends $thr_timeout->join(); #wait for the timeout thread ends Code of timeout function sub timeout { $timeout = false; my $start_time = time(); while (!$exit_thread) { sleep(1); last if (main function is executed); if (time() - $start_time >= configured time ) { logmsg "process is killed as request timed out"; _kill_remote_process(); $timeout = true; last; } } } now the code is running as i expected, but i am just not very clear if the code $exit_thread = true works because there is a "last" at the end of while loop. Can anybody give me a answer? Thanks

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• The cross-thread usage of "HttpContext.Current" property and related things

  - by smwikipedia

  I read from < Essential ASP.NET with Examples in C# the following statement: Another useful property to know about is the static Current property of the HttpContext class. This property always points to the current instance of the HttpContext class for the request being serviced. This can be convenient if you are writing helper classes that will be used from pages or other pipeline classes and may need to access the context for whatever reason. By using the static Current property to retrieve the context, you can avoid passing a reference to it to helper classes. For example, the class shown in Listing 4-1 uses the Current property of the context to access the QueryString and print something to the current response buffer. Note that for this static property to be correctly initialized, the caller must be executing on the original request thread, so if you have spawned additional threads to perform work during a request, you must take care to provide access to the context class yourself. I am wondering about the root cause of the bold part, and one thing leads to another, here is my thoughts: We know that a process can have multiple threads. Each of these threads have their own stacks, respectively. These threads also have access to a shared memory area, the heap. The stack then, as I understand it, is kind of where all the context for that thread is stored. For a thread to access something in the heap it must use a pointer, and the pointer is stored on its stack. So when we make some cross-thread calls, we must make sure that all the necessary context info is passed from the caller thread's stack to the callee thread's stack. But I am not quite sure if I made any mistake. Any comments will be deeply appreciated. Thanks. ADD Here the stack is limited to user stack.

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• Why are my thread being terminated ?

  - by Sephy

  Hi, I'm trying to repeat calls to methods through 3 differents threads. But after I start my threads, during the next iteration of my loop, they are all terminated so nothing is executed... The code is as follows : public static void main(String[] args) { main = new Main(); pollingThread.start(); } static Thread pollingThread = new Thread() { @Override public void run() { while (isRunning) { main.poll(); // test the state of the threads try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } }; }; public void poll() { if (clientThread == null) { clientThread = new Thread(new Runnable() { @Override public void run() { //create some objects } }); clientThread.start(); } else if (clientThread.isAlive()) { // do some treatment } if (gestionnaireThread == null) { gestionnaireThread = new Thread(new Runnable() { @Override public void run() { //create some objects }; }); gestionnaireThread.start(); } else if (gestionnaireThread.isAlive()) { // do some treatment } if (marchandThread == null) { marchandThread = new Thread(new Runnable() { @Override public void run() { // create some objects }; }); marchandThread.start(); } else if (marchandThread.isAlive()) { // do some treatment } } And for some reason, when I test the state of my different threads, they appear as runnable and then a the 2nd iteration, they are all terminated... What am I doing wrong? I actually have no error, but the threads are terminated and so my loop keeps looping and telling me the threads are terminated.... Thanks for any help.

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• run two thread at the same time in java

  - by user1805005

  i have used timertask to schedule my java program. now when the run method of timertask is in process, i want to run two threads which run at the same time and do different functions. here is my code.. please help me.. import java.util.Calendar; import java.util.Date; import java.util.Timer; import java.util.TimerTask; public class timercheck extends TimerTask{ // my first thread Thread t1 = new Thread(){ public void run(){ for(int i = 1;i <= 10;i++) { System.out.println(i); } } }; // my second thread Thread t2 = new Thread(){ public void run(){ for(int i = 11;i <= 20;i++) { System.out.println(i); } } }; public static void main(String[] args){ long ONCE_PER_DAY = 1000*60*60*24; Calendar calendar = Calendar.getInstance(); calendar.set(Calendar.HOUR_OF_DAY, 12); calendar.set(Calendar.MINUTE, 05); calendar.set(Calendar.SECOND, 00); Date time = calendar.getTime(); TimerTask check = new timercheck(); Timer timer = new Timer(); timer.scheduleAtFixedRate(check, time ,ONCE_PER_DAY); } @Override // run method of timer task public void run() { t1.start(); t2.start(); } }

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• Getting a per thread cpu stats

  - by viraptor

  I'm interested in the current usage of cpu - precisely cpu% and wait% - for each thread in a specific application. Is it possible to get that information from somewhere? I know that top can split information per real thread (ones with pid), but it doesn't show the system/user/wait cpu usage split for each of them. I would also like some way to log that info. Do you know any apps (or apis) that can do that?

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• Oracle Coherence, Split-Brain and Recovery Protocols In Detail

  - by Ricardo Ferreira

  This article provides a high level conceptual overview of Split-Brain scenarios in distributed systems. It will focus on a specific example of cluster communication failure and recovery in Oracle Coherence. This includes a discussion on the witness protocol (used to remove failed cluster members) and the panic protocol (used to resolve Split-Brain scenarios). Note that the removal of cluster members does not necessarily indicate a Split-Brain condition. Oracle Coherence does not (and cannot) detect a Split-Brain as it occurs, the condition is only detected when cluster members that previously lost contact with each other regain contact. Cluster Topology and Configuration In order to create an good didactic for the article, let's assume a cluster topology and configuration. In this example we have a six member cluster, consisting of one JVM on each physical machine. The member IDs are as follows: Member ID  IP Address  1  10.149.155.76  2  10.149.155.77  3  10.149.155.236  4  10.149.155.75  5  10.149.155.79  6  10.149.155.78 Members 1, 2, and 3 are connected to a switch, and members 4, 5, and 6 are connected to a second switch. There is a link between the two switches, which provides network connectivity between all of the machines. Member 1 is the first member to join this cluster, thus making it the senior member. Member 6 is the last member to join this cluster. Here is a log snippet from Member 6 showing the complete member set: 2010-02-26 15:27:57.390/3.062 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=main, member=6): Started DefaultCacheServer... SafeCluster: Name=cluster:0xDDEB Group{Address=224.3.5.3, Port=35465, TTL=4} MasterMemberSet ( ThisMember=Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) OldestMember=Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) ActualMemberSet=MemberSet(Size=6, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=5, Timestamp=2010-02-26 15:27:49.095, Address=10.149.155.79:8088, MachineId=1103, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:3229, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) RecycleMillis=120000 RecycleSet=MemberSet(Size=0, BitSetCount=0 ) ) At approximately 15:30, the connection between the two switches is severed: Thirty seconds later (the default packet timeout in development mode) the logs indicate communication failures across the cluster. In this example, the communication failure was caused by a network failure. In a production setting, this type of communication failure can have many root causes, including (but not limited to) network failures, excessive GC, high CPU utilization, swapping/virtual memory, and exceeding maximum network bandwidth. In addition, this type of failure is not necessarily indicative of a split brain. Any communication failure will be logged in this fashion. Member 2 logs a communication failure with Member 5: 2010-02-26 15:30:32.638/196.928 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=2): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=5, Timestamp=2010-02-26 15:27:49.095, Address=10.149.155.79:8088, MachineId=1103, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:3229, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) ) The Coherence clustering protocol (TCMP) is a reliable transport mechanism built on UDP. In order for the protocol to be reliable, it requires an acknowledgement (ACK) for each packet delivered. If a packet fails to be acknowledged within the configured timeout period, the Coherence cluster member will log a packet timeout (as seen in the log message above). When this occurs, the cluster member will consult with other members to determine who is at fault for the communication failure. If the witness members agree that the suspect member is at fault, the suspect is removed from the cluster. If the witnesses unanimously disagree, the accuser is removed. This process is known as the witness protocol. Since Member 2 cannot communicate with Member 5, it selects two witnesses (Members 1 and 4) to determine if the communication issue is with Member 5 or with itself (Member 2). However, Member 4 is on the switch that is no longer accessible by Members 1, 2 and 3; thus a packet timeout for member 4 is recorded as well: 2010-02-26 15:30:35.648/199.938 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=2): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) Member 1 has the ability to confirm the departure of member 4, however Member 6 cannot as it is also inaccessible. At the same time, Member 3 sends a request to remove Member 6, which is followed by a report from Member 3 indicating that Member 6 has departed the cluster: 2010-02-26 15:30:35.706/199.996 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=2): MemberLeft request for Member 6 received from Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) 2010-02-26 15:30:35.709/199.999 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=2): MemberLeft notification for Member 6 received from Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) The log for Member 3 determines how Member 6 departed the cluster: 2010-02-26 15:30:35.161/191.694 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=3): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) ) 2010-02-26 15:30:35.165/191.698 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=3): Member departure confirmed by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) ); removing Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) In this case, Member 3 happened to select two witnesses that it still had connectivity with (Members 1 and 2) thus resulting in a simple decision to remove Member 6. Given the departure of Member 6, Member 2 is left with a single witness to confirm the departure of Member 4: 2010-02-26 15:30:35.713/200.003 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=2): Member departure confirmed by MemberSet(Size=1, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) ); removing Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) In the meantime, Member 4 logs a missing heartbeat from the senior member. This message is also logged on Members 5 and 6. 2010-02-26 15:30:07.906/150.453 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=PacketListenerN, member=4): Scheduled senior member heartbeat is overdue; rejoining multicast group. Next, Member 4 logs a TcpRing failure with Member 2, thus resulting in the termination of Member 2: 2010-02-26 15:30:21.421/163.968 Oracle Coherence GE 3.5.3/465p2 <D4> (thread=Cluster, member=4): TcpRing: Number of socket exceptions exceeded maximum; last was "java.net.SocketTimeoutException: connect timed out"; removing the member: 2 For quick process termination detection, Oracle Coherence utilizes a feature called TcpRing which is a sparse collection of TCP/IP-based connections between different members in the cluster. Each member in the cluster is connected to at least one other member, which (if at all possible) is running on a different physical box. This connection is not used for any data transfer, only heartbeat communications are sent once a second per each link. If a certain number of exceptions are thrown while trying to re-establish a connection, the member throwing the exceptions is removed from the cluster. Member 5 logs a packet timeout with Member 3 and cites witnesses Members 4 and 6: 2010-02-26 15:30:29.791/165.037 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=5): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) 2010-02-26 15:30:29.798/165.044 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=5): Member departure confirmed by MemberSet(Size=2, BitSetCount=2 Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ); removing Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) Eventually we are left with two distinct clusters consisting of Members 1, 2, 3 and Members 4, 5, 6, respectively. In the latter cluster, Member 4 is promoted to senior member. The connection between the two switches is restored at 15:33. Upon the restoration of the connection, the cluster members immediately receive cluster heartbeats from the two senior members. In the case of Members 1, 2, and 3, the following is logged: 2010-02-26 15:33:14.970/369.066 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=1): The member formerly known as Member(Id=4, Timestamp=2010-02-26 15:30:35.341, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) has been forcefully evicted from the cluster, but continues to emit a cluster heartbeat; henceforth, the member will be shunned and its messages will be ignored. Likewise for Members 4, 5, and 6: 2010-02-26 15:33:14.343/336.890 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=4): The member formerly known as Member(Id=1, Timestamp=2010-02-26 15:30:31.64, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) has been forcefully evicted from the cluster, but continues to emit a cluster heartbeat; henceforth, the member will be shunned and its messages will be ignored. This message indicates that a senior heartbeat is being received from members that were previously removed from the cluster, in other words, something that should not be possible. For this reason, the recipients of these messages will initially ignore them. After several iterations of these messages, the existence of multiple clusters is acknowledged, thus triggering the panic protocol to reconcile this situation. When the presence of more than one cluster (i.e. Split-Brain) is detected by a Coherence member, the panic protocol is invoked in order to resolve the conflicting clusters and consolidate into a single cluster. The protocol consists of the removal of smaller clusters until there is one cluster remaining. In the case of equal size clusters, the one with the older Senior Member will survive. Member 1, being the oldest member, initiates the protocol: 2010-02-26 15:33:45.970/400.066 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=1): An existence of a cluster island with senior Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) containing 3 nodes have been detected. Since this Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) is the senior of an older cluster island, the panic protocol is being activated to stop the other island's senior and all junior nodes that belong to it. Member 3 receives the panic: 2010-02-26 15:33:45.803/382.336 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=3): Received panic from senior Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) caused by Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member 4, the senior member of the younger cluster, receives the kill message from Member 3: 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. In turn, Member 4 requests the departure of its junior members 5 and 6: 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. 2010-02-26 15:33:43.343/349.015 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=6): Received a Kill message from a valid Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer); stopping cluster service. Once Members 4, 5, and 6 restart, they rejoin the original cluster with senior member 1. The log below is from Member 4. Note that it receives a different member id when it rejoins the cluster. 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. 2010-02-26 15:33:46.921/369.468 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Service Cluster left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Invocation:InvocationService, member=4): Service InvocationService left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=OptimisticCache, member=4): Service OptimisticCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=ReplicatedCache, member=4): Service ReplicatedCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=DistributedCache, member=4): Service DistributedCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Invocation:Management, member=4): Service Management left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service Management with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service DistributedCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service ReplicatedCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service OptimisticCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service InvocationService with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member(Id=6, Timestamp=2010-02-26 15:33:47.046, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) left Cluster with senior member 4 2010-02-26 15:33:49.218/371.765 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=main, member=n/a): Restarting cluster 2010-02-26 15:33:49.421/371.968 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=n/a): Service Cluster joined the cluster with senior service member n/a 2010-02-26 15:33:49.625/372.172 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=n/a): This Member(Id=5, Timestamp=2010-02-26 15:33:50.499, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer, Edition=Grid Edition, Mode=Development, CpuCount=2, SocketCount=1) joined cluster "cluster:0xDDEB" with senior Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer, Edition=Grid Edition, Mode=Development, CpuCount=2, SocketCount=2) Cool isn't it?

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• Creating STA COM compatible ASP.NET Applications

  - by Rick Strahl

  When building ASP.NET applications that interface with old school COM objects like those created with VB6 or Visual FoxPro (MTDLL), it's extremely important that the threads that are serving requests use Single Threaded Apartment Threading. STA is a COM built-in technology that allows essentially single threaded components to operate reliably in a multi-threaded environment. STA's guarantee that COM objects instantiated on a specific thread stay on that specific thread and any access to a COM object from another thread automatically marshals that thread to the STA thread. The end effect is that you can have multiple threads, but a COM object instance lives on a fixed never changing thread. ASP.NET by default uses MTA (multi-threaded apartment) threads which are truly free spinning threads that pay no heed to COM object marshaling. This is vastly more efficient than STA threading which has a bit of overhead in determining whether it's OK to run code on a given thread or whether some sort of thread/COM marshaling needs to occur. MTA COM components can be very efficient, but STA COM components in a multi-threaded environment always tend to have a fair amount of overhead. It's amazing how much COM Interop I still see today so while it seems really old school to be talking about this topic, it's actually quite apropos for me as I have many customers using legacy COM systems that need to interface with other .NET applications. In this post I'm consolidating some of the hacks I've used to integrate with various ASP.NET technologies when using STA COM Components. STA in ASP.NET Support for STA threading in the ASP.NET framework is fairly limited. Specifically only the original ASP.NET WebForms technology supports STA threading directly via its STA Page Handler implementation or what you might know as ASPCOMPAT mode. For WebForms running STA components is as easy as specifying the ASPCOMPAT attribute in the @Page tag:<%@ Page Language="C#" AspCompat="true" %> which runs the page in STA mode. Removing it runs in MTA mode. Simple. Unfortunately all other ASP.NET technologies built on top of the core ASP.NET engine do not support STA natively. So if you want to use STA COM components in MVC or with class ASMX Web Services, there's no automatic way like the ASPCOMPAT keyword available. So what happens when you run an STA COM component in an MTA application? In low volume environments - nothing much will happen. The COM objects will appear to work just fine as there are no simultaneous thread interactions and the COM component will happily run on a single thread or multiple single threads one at a time. So for testing running components in MTA environments may appear to work just fine. However as load increases and threads get re-used by ASP.NET COM objects will end up getting created on multiple different threads. This can result in crashes or hangs, or data corruption in the STA components which store their state in thread local storage on the STA thread. If threads overlap this global store can easily get corrupted which in turn causes problems. STA ensures that any COM object instance loaded always stays on the same thread it was instantiated on. What about COM+? COM+ is supposed to address the problem of STA in MTA applications by providing an abstraction with it's own thread pool manager for COM objects. It steps in to the COM instantiation pipeline and hands out COM instances from its own internally maintained STA Thread pool. This guarantees that the COM instantiation threads are STA threads if using STA components. COM+ works, but in my experience the technology is very, very slow for STA components. It adds a ton of overhead and reduces COM performance noticably in load tests in IIS. COM+ can make sense in some situations but for Web apps with STA components it falls short. In addition there's also the need to ensure that COM+ is set up and configured on the target machine and the fact that components have to be registered in COM+. COM+ also keeps components up at all times, so if a component needs to be replaced the COM+ package needs to be unloaded (same is true for IIS hosted components but it's more common to manage that). COM+ is an option for well established components, but native STA support tends to provide better performance and more consistent usability, IMHO. STA for non supporting ASP.NET Technologies As mentioned above only WebForms supports STA natively. However, by utilizing the WebForms ASP.NET Page handler internally it's actually possible to trick various other ASP.NET technologies and let them work with STA components. This is ugly but I've used each of these in various applications and I've had minimal problems making them work with FoxPro STA COM components which is about as dififcult as it gets for COM Interop in .NET. In this post I summarize several STA workarounds that enable you to use STA threading with these ASP.NET Technologies: ASMX Web Services ASP.NET MVC WCF Web Services ASP.NET Web API ASMX Web Services I start with classic ASP.NET ASMX Web Services because it's the easiest mechanism that allows for STA modification. It also clearly demonstrates how the WebForms STA Page Handler is the key technology to enable the various other solutions to create STA components. Essentially the way this works is to override the WebForms Page class and hijack it's init functionality for processing requests. Here's what this looks like for Web Services:namespace FoxProAspNet { public class WebServiceStaHandler : System.Web.UI.Page, IHttpAsyncHandler { protected override void OnInit(EventArgs e) { IHttpHandler handler = new WebServiceHandlerFactory().GetHandler( this.Context, this.Context.Request.HttpMethod, this.Context.Request.FilePath, this.Context.Request.PhysicalPath); handler.ProcessRequest(this.Context); this.Context.ApplicationInstance.CompleteRequest(); } public IAsyncResult BeginProcessRequest( HttpContext context, AsyncCallback cb, object extraData) { return this.AspCompatBeginProcessRequest(context, cb, extraData); } public void EndProcessRequest(IAsyncResult result) { this.AspCompatEndProcessRequest(result); } } public class AspCompatWebServiceStaHandlerWithSessionState : WebServiceStaHandler, IRequiresSessionState { } } This class overrides the ASP.NET WebForms Page class which has a little known AspCompatBeginProcessRequest() and AspCompatEndProcessRequest() method that is responsible for providing the WebForms ASPCOMPAT functionality. These methods handle routing requests to STA threads. Note there are two classes - one that includes session state and one that does not. If you plan on using ASP.NET Session state use the latter class, otherwise stick to the former. This maps to the EnableSessionState page setting in WebForms. This class simply hooks into this functionality by overriding the BeginProcessRequest and EndProcessRequest methods and always forcing it into the AspCompat methods. The way this works is that BeginProcessRequest() fires first to set up the threads and starts intializing the handler. As part of that process the OnInit() method is fired which is now already running on an STA thread. The code then creates an instance of the actual WebService handler factory and calls its ProcessRequest method to start executing which generates the Web Service result. Immediately after ProcessRequest the request is stopped with Application.CompletRequest() which ensures that the rest of the Page handler logic doesn't fire. This means that even though the fairly heavy Page class is overridden here, it doesn't end up executing any of its internal processing which makes this code fairly efficient. In a nutshell, we're highjacking the Page HttpHandler and forcing it to process the WebService process handler in the context of the AspCompat handler behavior. Hooking up the Handler Because the above is an HttpHandler implementation you need to hook up the custom handler and replace the standard ASMX handler. To do this you need to modify the web.config file (here for IIS 7 and IIS Express): <configuration> <system.webServer> <handlers> <remove name="WebServiceHandlerFactory-Integrated-4.0" /> <add name="Asmx STA Web Service Handler" path="*.asmx" verb="*" type="FoxProAspNet.WebServiceStaHandler" precondition="integrated"/> </handlers> </system.webServer> </configuration> (Note: The name for the WebServiceHandlerFactory-Integrated-4.0 might be slightly different depending on your server version. Check the IIS Handler configuration in the IIS Management Console for the exact name or simply remove the handler from the list there which will propagate to your web.config). For IIS 5 & 6 (Windows XP/2003) or the Visual Studio Web Server use:<configuration> <system.web> <httpHandlers> <remove path="*.asmx" verb="*" /> <add path="*.asmx" verb="*" type="FoxProAspNet.WebServiceStaHandler" /> </httpHandlers> </system.web></configuration> To test, create a new ASMX Web Service and create a method like this: [WebService(Namespace = "http://foxaspnet.org/")] [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)] public class FoxWebService : System.Web.Services.WebService { [WebMethod] public string HelloWorld() { return "Hello World. Threading mode is: " + System.Threading.Thread.CurrentThread.GetApartmentState(); } } Run this before you put in the web.config configuration changes and you should get: Hello World. Threading mode is: MTA Then put the handler mapping into Web.config and you should see: Hello World. Threading mode is: STA And you're on your way to using STA COM components. It's a hack but it works well! I've used this with several high volume Web Service installations with various customers and it's been fast and reliable. ASP.NET MVC ASP.NET MVC has quickly become the most popular ASP.NET technology, replacing WebForms for creating HTML output. MVC is more complex to get started with, but once you understand the basic structure of how requests flow through the MVC pipeline it's easy to use and amazingly flexible in manipulating HTML requests. In addition, MVC has great support for non-HTML output sources like JSON and XML, making it an excellent choice for AJAX requests without any additional tools. Unlike WebForms ASP.NET MVC doesn't support STA threads natively and so some trickery is needed to make it work with STA threads as well. MVC gets its handler implementation through custom route handlers using ASP.NET's built in routing semantics. To work in an STA handler requires working in the Page Handler as part of the Route Handler implementation. As with the Web Service handler the first step is to create a custom HttpHandler that can instantiate an MVC request pipeline properly:public class MvcStaThreadHttpAsyncHandler : Page, IHttpAsyncHandler, IRequiresSessionState { private RequestContext _requestContext; public MvcStaThreadHttpAsyncHandler(RequestContext requestContext) { if (requestContext == null) throw new ArgumentNullException("requestContext"); _requestContext = requestContext; } public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, object extraData) { return this.AspCompatBeginProcessRequest(context, cb, extraData); } protected override void OnInit(EventArgs e) { var controllerName = _requestContext.RouteData.GetRequiredString("controller"); var controllerFactory = ControllerBuilder.Current.GetControllerFactory(); var controller = controllerFactory.CreateController(_requestContext, controllerName); if (controller == null) throw new InvalidOperationException("Could not find controller: " + controllerName); try { controller.Execute(_requestContext); } finally { controllerFactory.ReleaseController(controller); } this.Context.ApplicationInstance.CompleteRequest(); } public void EndProcessRequest(IAsyncResult result) { this.AspCompatEndProcessRequest(result); } public override void ProcessRequest(HttpContext httpContext) { throw new NotSupportedException("STAThreadRouteHandler does not support ProcessRequest called (only BeginProcessRequest)"); } } This handler code figures out which controller to load and then executes the controller. MVC internally provides the information needed to route to the appropriate method and pass the right parameters. Like the Web Service handler the logic occurs in the OnInit() and performs all the processing in that part of the request. Next, we need a RouteHandler that can actually pick up this handler. Unlike the Web Service handler where we simply registered the handler, MVC requires a RouteHandler to pick up the handler. RouteHandlers look at the URL's path and based on that decide on what handler to invoke. The route handler is pretty simple - all it does is load our custom handler: public class MvcStaThreadRouteHandler : IRouteHandler { public IHttpHandler GetHttpHandler(RequestContext requestContext) { if (requestContext == null) throw new ArgumentNullException("requestContext"); return new MvcStaThreadHttpAsyncHandler(requestContext); } } At this point you can instantiate this route handler and force STA requests to MVC by specifying a route. The following sets up the ASP.NET Default Route:Route mvcRoute = new Route("{controller}/{action}/{id}", new RouteValueDictionary( new { controller = "Home", action = "Index", id = UrlParameter.Optional }), new MvcStaThreadRouteHandler()); RouteTable.Routes.Add(mvcRoute);   To make this code a little easier to work with and mimic the behavior of the routes.MapRoute() functionality extension method that MVC provides, here is an extension method for MapMvcStaRoute(): public static class RouteCollectionExtensions { public static void MapMvcStaRoute(this RouteCollection routeTable, string name, string url, object defaults = null) { Route mvcRoute = new Route(url, new RouteValueDictionary(defaults), new MvcStaThreadRouteHandler()); RouteTable.Routes.Add(mvcRoute); } } With this the syntax to add  route becomes a little easier and matches the MapRoute() method:RouteTable.Routes.MapMvcStaRoute( name: "Default", url: "{controller}/{action}/{id}", defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional } ); The nice thing about this route handler, STA Handler and extension method is that it's fully self contained. You can put all three into a single class file and stick it into your Web app, and then simply call MapMvcStaRoute() and it just works. Easy! To see whether this works create an MVC controller like this: public class ThreadTestController : Controller { public string ThreadingMode() { return Thread.CurrentThread.GetApartmentState().ToString(); } } Try this test both with only the MapRoute() hookup in the RouteConfiguration in which case you should get MTA as the value. Then change the MapRoute() call to MapMvcStaRoute() leaving all the parameters the same and re-run the request. You now should see STA as the result. You're on your way using STA COM components reliably in ASP.NET MVC. WCF Web Services running through IIS WCF Web Services provide a more robust and wider range of services for Web Services. You can use WCF over HTTP, TCP, and Pipes, and WCF services support WS* secure services. There are many features in WCF that go way beyond what ASMX can do. But it's also a bit more complex than ASMX. As a basic rule if you need to serve straight SOAP Services over HTTP I 'd recommend sticking with the simpler ASMX services especially if COM is involved. If you need WS* support or want to serve data over non-HTTP protocols then WCF makes more sense. WCF is not my forte but I found a solution from Scott Seely on his blog that describes the progress and that seems to work well. I'm copying his code below so this STA information is all in one place and quickly explain. Scott's code basically works by creating a custom OperationBehavior which can be specified via an [STAOperation] attribute on every method. Using his attribute you end up with a class (or Interface if you separate the contract and class) that looks like this: [ServiceContract] public class WcfService { [OperationContract] public string HelloWorldMta() { return Thread.CurrentThread.GetApartmentState().ToString(); } // Make sure you use this custom STAOperationBehavior // attribute to force STA operation of service methods [STAOperationBehavior] [OperationContract] public string HelloWorldSta() { return Thread.CurrentThread.GetApartmentState().ToString(); } } Pretty straight forward. The latter method returns STA while the former returns MTA. To make STA work every method needs to be marked up. The implementation consists of the attribute and OperationInvoker implementation. Here are the two classes required to make this work from Scott's post:public class STAOperationBehaviorAttribute : Attribute, IOperationBehavior { public void AddBindingParameters(OperationDescription operationDescription, System.ServiceModel.Channels.BindingParameterCollection bindingParameters) { } public void ApplyClientBehavior(OperationDescription operationDescription, System.ServiceModel.Dispatcher.ClientOperation clientOperation) { // If this is applied on the client, well, it just doesn’t make sense. // Don’t throw in case this attribute was applied on the contract // instead of the implementation. } public void ApplyDispatchBehavior(OperationDescription operationDescription, System.ServiceModel.Dispatcher.DispatchOperation dispatchOperation) { // Change the IOperationInvoker for this operation. dispatchOperation.Invoker = new STAOperationInvoker(dispatchOperation.Invoker); } public void Validate(OperationDescription operationDescription) { if (operationDescription.SyncMethod == null) { throw new InvalidOperationException("The STAOperationBehaviorAttribute " + "only works for synchronous method invocations."); } } } public class STAOperationInvoker : IOperationInvoker { IOperationInvoker _innerInvoker; public STAOperationInvoker(IOperationInvoker invoker) { _innerInvoker = invoker; } public object[] AllocateInputs() { return _innerInvoker.AllocateInputs(); } public object Invoke(object instance, object[] inputs, out object[] outputs) { // Create a new, STA thread object[] staOutputs = null; object retval = null; Thread thread = new Thread( delegate() { retval = _innerInvoker.Invoke(instance, inputs, out staOutputs); }); thread.SetApartmentState(ApartmentState.STA); thread.Start(); thread.Join(); outputs = staOutputs; return retval; } public IAsyncResult InvokeBegin(object instance, object[] inputs, AsyncCallback callback, object state) { // We don’t handle async… throw new NotImplementedException(); } public object InvokeEnd(object instance, out object[] outputs, IAsyncResult result) { // We don’t handle async… throw new NotImplementedException(); } public bool IsSynchronous { get { return true; } } } The key in this setup is the Invoker and the Invoke method which creates a new thread and then fires the request on this new thread. Because this approach creates a new thread for every request it's not super efficient. There's a bunch of overhead involved in creating the thread and throwing it away after each thread, but it'll work for low volume requests and insure each thread runs in STA mode. If better performance is required it would be useful to create a custom thread manager that can pool a number of STA threads and hand off threads as needed rather than creating new threads on every request. If your Web Service needs are simple and you need only to serve standard SOAP 1.x requests, I would recommend sticking with ASMX services. It's easier to set up and work with and for STA component use it'll be significantly better performing since ASP.NET manages the STA thread pool for you rather than firing new threads for each request. One nice thing about Scotts code is though that it works in any WCF environment including self hosting. It has no dependency on ASP.NET or WebForms for that matter. STA - If you must STA components are a  pain in the ass and thankfully there isn't too much stuff out there anymore that requires it. But when you need it and you need to access STA functionality from .NET at least there are a few options available to make it happen. Each of these solutions is a bit hacky, but they work - I've used all of them in production with good results with FoxPro components. I hope compiling all of these in one place here makes it STA consumption a little bit easier. I feel your pain :-) Resources Download STA Handler Code Examples Scott Seely's original STA WCF OperationBehavior Article© Rick Strahl, West Wind Technologies, 2005-2012Posted in FoxPro   ASP.NET  .NET  COM   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• EMERGENCY - Major Problems After Perl Module Installed via WHM

  - by Russell C.

  I attempted to install the perl module Net::Twitter::Role::API::Lists using WHM and after doing so my whole site came down. It seems that something that was updated with the install isn't functioning correctly and since our website it written in Perl none of our site scripts will run. In almost 8 years of working with Perl I've never had any issues arise after installing a perl module so I have no idea how to even start troubleshooting. The error I see when trying to compile any of our Perl scripts is below. I'd appreciate any advice on what might be wrong and steps on how I can go about resolve it. Thanks in advance for your help! Attribute (+type_constraint) of class MooseX::AttributeHelpers::Counter has no associated methods (did you mean to provide an "is" argument?) at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Attribute.pm line 551 Moose::Meta::Attribute::_check_associated_methods('Moose::Meta::Attribute=HASH(0x9ae35b4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Class.pm line 303 Moose::Meta::Class::add_attribute('Moose::Meta::Class=HASH(0xa4d7718)', 'Moose::Meta::Attribute=HASH(0x9ae35b4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 142 Moose::Meta::Role::Application::ToClass::apply_attributes('Moose::Meta::Role::Application::ToClass=HASH(0xa4dfb38)', 'Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application.pm line 72 Moose::Meta::Role::Application::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4dfb38)', 'Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 31 Moose::Meta::Role::Application::ToClass::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4dfb38)', 'Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role.pm line 419 Moose::Meta::Role::apply('Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 132 Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0xa4d7718)', 'undef', 'MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 86 Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0xa4d7718)', 'MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose.pm line 57 Moose::with('Moose::Meta::Class=HASH(0xa4d7718)', 'MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Exporter.pm line 293 Moose::with('MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 10 require MooseX/AttributeHelpers/Counter.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers.pm line 23 MooseX::AttributeHelpers::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/AttributeHelpers.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute/Role/Meta/Class.pm line 6 MooseX::ClassAttribute::Role::Meta::Class::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/ClassAttribute/Role/Meta/Class.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute.pm line 11 MooseX::ClassAttribute::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/ClassAttribute.pm called at /usr/lib/perl5/site_perl/5.8.8/Olson/Abbreviations.pm line 6 Olson::Abbreviations::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require Olson/Abbreviations.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTime/ButMaintained.pm line 10 MooseX::Types::DateTime::ButMaintained::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/Types/DateTime/ButMaintained.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTimeX.pm line 9 MooseX::Types::DateTimeX::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/Types/DateTimeX.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3/Client/Bucket.pm line 5 Net::Amazon::S3::Client::Bucket::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require Net/Amazon/S3/Client/Bucket.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3.pm line 111 Net::Amazon::S3::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require Net/Amazon/S3.pm called at /home/atrails/www/cgi-bin/main.pm line 1633 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require main.pm called at /home/atrails/cron/meetup.pl line 20 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 Attribute (+default) of class MooseX::AttributeHelpers::Counter has no associated methods (did you mean to provide an "is" argument?) at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Attribute.pm line 551 Moose::Meta::Attribute::_check_associated_methods('Moose::Meta::Attribute=HASH(0xa4df4b4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Class.pm line 303 Moose::Meta::Class::add_attribute('Moose::Meta::Class=HASH(0xa4d7718)', 'Moose::Meta::Attribute=HASH(0xa4df4b4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 142 Moose::Meta::Role::Application::ToClass::apply_attributes('Moose::Meta::Role::Application::ToClass=HASH(0xa4dfb38)', 'Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application.pm line 72 Moose::Meta::Role::Application::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4dfb38)', 'Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 31 Moose::Meta::Role::Application::ToClass::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4dfb38)', 'Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role.pm line 419 Moose::Meta::Role::apply('Moose::Meta::Role=HASH(0xa3dbdec)', 'Moose::Meta::Class=HASH(0xa4d7718)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 132 Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0xa4d7718)', 'undef', 'MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 86 Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0xa4d7718)', 'MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose.pm line 57 Moose::with('Moose::Meta::Class=HASH(0xa4d7718)', 'MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Exporter.pm line 293 Moose::with('MooseX::AttributeHelpers::Trait::Counter') called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 10 require MooseX/AttributeHelpers/Counter.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers.pm line 23 MooseX::AttributeHelpers::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/AttributeHelpers.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute/Role/Meta/Class.pm line 6 MooseX::ClassAttribute::Role::Meta::Class::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/ClassAttribute/Role/Meta/Class.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute.pm line 11 MooseX::ClassAttribute::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/ClassAttribute.pm called at /usr/lib/perl5/site_perl/5.8.8/Olson/Abbreviations.pm line 6 Olson::Abbreviations::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require Olson/Abbreviations.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTime/ButMaintained.pm line 10 MooseX::Types::DateTime::ButMaintained::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/Types/DateTime/ButMaintained.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTimeX.pm line 9 MooseX::Types::DateTimeX::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require MooseX/Types/DateTimeX.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3/Client/Bucket.pm line 5 Net::Amazon::S3::Client::Bucket::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require Net/Amazon/S3/Client/Bucket.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3.pm line 111 Net::Amazon::S3::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require Net/Amazon/S3.pm called at /home/atrails/www/cgi-bin/main.pm line 1633 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 require main.pm called at /home/atrails/cron/meetup.pl line 20 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Counter.pm line 0 Attribute (+type_constraint) of class MooseX::AttributeHelpers::Number has no associated methods (did you mean to provide an "is" argument?) at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Attribute.pm line 551 Moose::Meta::Attribute::_check_associated_methods('Moose::Meta::Attribute=HASH(0xa4ea48c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Class.pm line 303 Moose::Meta::Class::add_attribute('Moose::Meta::Class=HASH(0xa4f778c)', 'Moose::Meta::Attribute=HASH(0xa4ea48c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 142 Moose::Meta::Role::Application::ToClass::apply_attributes('Moose::Meta::Role::Application::ToClass=HASH(0xa4f8014)', 'Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application.pm line 72 Moose::Meta::Role::Application::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4f8014)', 'Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 31 Moose::Meta::Role::Application::ToClass::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4f8014)', 'Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role.pm line 419 Moose::Meta::Role::apply('Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 132 Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0xa4f778c)', 'undef', 'MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 86 Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0xa4f778c)', 'MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose.pm line 57 Moose::with('Moose::Meta::Class=HASH(0xa4f778c)', 'MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Exporter.pm line 293 Moose::with('MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 9 require MooseX/AttributeHelpers/Number.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers.pm line 24 MooseX::AttributeHelpers::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/AttributeHelpers.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute/Role/Meta/Class.pm line 6 MooseX::ClassAttribute::Role::Meta::Class::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/ClassAttribute/Role/Meta/Class.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute.pm line 11 MooseX::ClassAttribute::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/ClassAttribute.pm called at /usr/lib/perl5/site_perl/5.8.8/Olson/Abbreviations.pm line 6 Olson::Abbreviations::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require Olson/Abbreviations.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTime/ButMaintained.pm line 10 MooseX::Types::DateTime::ButMaintained::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/Types/DateTime/ButMaintained.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTimeX.pm line 9 MooseX::Types::DateTimeX::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/Types/DateTimeX.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3/Client/Bucket.pm line 5 Net::Amazon::S3::Client::Bucket::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require Net/Amazon/S3/Client/Bucket.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3.pm line 111 Net::Amazon::S3::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require Net/Amazon/S3.pm called at /home/atrails/www/cgi-bin/main.pm line 1633 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require main.pm called at /home/atrails/cron/meetup.pl line 20 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 Attribute (+default) of class MooseX::AttributeHelpers::Number has no associated methods (did you mean to provide an "is" argument?) at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Attribute.pm line 551 Moose::Meta::Attribute::_check_associated_methods('Moose::Meta::Attribute=HASH(0xa4f7804)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Class.pm line 303 Moose::Meta::Class::add_attribute('Moose::Meta::Class=HASH(0xa4f778c)', 'Moose::Meta::Attribute=HASH(0xa4f7804)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 142 Moose::Meta::Role::Application::ToClass::apply_attributes('Moose::Meta::Role::Application::ToClass=HASH(0xa4f8014)', 'Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application.pm line 72 Moose::Meta::Role::Application::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4f8014)', 'Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 31 Moose::Meta::Role::Application::ToClass::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa4f8014)', 'Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role.pm line 419 Moose::Meta::Role::apply('Moose::Meta::Role=HASH(0xa38b764)', 'Moose::Meta::Class=HASH(0xa4f778c)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 132 Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0xa4f778c)', 'undef', 'MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 86 Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0xa4f778c)', 'MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose.pm line 57 Moose::with('Moose::Meta::Class=HASH(0xa4f778c)', 'MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Exporter.pm line 293 Moose::with('MooseX::AttributeHelpers::Trait::Number') called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 9 require MooseX/AttributeHelpers/Number.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers.pm line 24 MooseX::AttributeHelpers::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/AttributeHelpers.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute/Role/Meta/Class.pm line 6 MooseX::ClassAttribute::Role::Meta::Class::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/ClassAttribute/Role/Meta/Class.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute.pm line 11 MooseX::ClassAttribute::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/ClassAttribute.pm called at /usr/lib/perl5/site_perl/5.8.8/Olson/Abbreviations.pm line 6 Olson::Abbreviations::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require Olson/Abbreviations.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTime/ButMaintained.pm line 10 MooseX::Types::DateTime::ButMaintained::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/Types/DateTime/ButMaintained.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTimeX.pm line 9 MooseX::Types::DateTimeX::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require MooseX/Types/DateTimeX.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3/Client/Bucket.pm line 5 Net::Amazon::S3::Client::Bucket::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require Net/Amazon/S3/Client/Bucket.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3.pm line 111 Net::Amazon::S3::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require Net/Amazon/S3.pm called at /home/atrails/www/cgi-bin/main.pm line 1633 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 require main.pm called at /home/atrails/cron/meetup.pl line 20 main::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/Number.pm line 0 Attribute (+type_constraint) of class MooseX::AttributeHelpers::String has no associated methods (did you mean to provide an "is" argument?) at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Attribute.pm line 551 Moose::Meta::Attribute::_check_associated_methods('Moose::Meta::Attribute=HASH(0xa4fdae0)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Class.pm line 303 Moose::Meta::Class::add_attribute('Moose::Meta::Class=HASH(0xa4fd5c4)', 'Moose::Meta::Attribute=HASH(0xa4fdae0)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 142 Moose::Meta::Role::Application::ToClass::apply_attributes('Moose::Meta::Role::Application::ToClass=HASH(0xa5002d8)', 'Moose::Meta::Role=HASH(0xa42a690)', 'Moose::Meta::Class=HASH(0xa4fd5c4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application.pm line 72 Moose::Meta::Role::Application::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa5002d8)', 'Moose::Meta::Role=HASH(0xa42a690)', 'Moose::Meta::Class=HASH(0xa4fd5c4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role/Application/ToClass.pm line 31 Moose::Meta::Role::Application::ToClass::apply('Moose::Meta::Role::Application::ToClass=HASH(0xa5002d8)', 'Moose::Meta::Role=HASH(0xa42a690)', 'Moose::Meta::Class=HASH(0xa4fd5c4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Meta/Role.pm line 419 Moose::Meta::Role::apply('Moose::Meta::Role=HASH(0xa42a690)', 'Moose::Meta::Class=HASH(0xa4fd5c4)') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 132 Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0xa4fd5c4)', 'undef', 'MooseX::AttributeHelpers::Trait::String') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Util.pm line 86 Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0xa4fd5c4)', 'MooseX::AttributeHelpers::Trait::String') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose.pm line 57 Moose::with('Moose::Meta::Class=HASH(0xa4fd5c4)', 'MooseX::AttributeHelpers::Trait::String') called at /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-multi/Moose/Exporter.pm line 293 Moose::with('MooseX::AttributeHelpers::Trait::String') called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 10 require MooseX/AttributeHelpers/String.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers.pm line 25 MooseX::AttributeHelpers::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 require MooseX/AttributeHelpers.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute/Role/Meta/Class.pm line 6 MooseX::ClassAttribute::Role::Meta::Class::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 require MooseX/ClassAttribute/Role/Meta/Class.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/ClassAttribute.pm line 11 MooseX::ClassAttribute::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 require MooseX/ClassAttribute.pm called at /usr/lib/perl5/site_perl/5.8.8/Olson/Abbreviations.pm line 6 Olson::Abbreviations::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 require Olson/Abbreviations.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTime/ButMaintained.pm line 10 MooseX::Types::DateTime::ButMaintained::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 require MooseX/Types/DateTime/ButMaintained.pm called at /usr/lib/perl5/site_perl/5.8.8/MooseX/Types/DateTimeX.pm line 9 MooseX::Types::DateTimeX::BEGIN() called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 eval {...} called at /usr/lib/perl5/site_perl/5.8.8/MooseX/AttributeHelpers/String.pm line 0 require MooseX/Types/DateTimeX.pm called at /usr/lib/perl5/site_perl/5.8.8/Net/Amazon/S3/Client/Bucket.pm line 5 Net::Amazon::S3::Client::Bucket::BEGIN() called at /usr/lib/perl5/site_per

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• Java Thread Management and Application Flow

  - by user119179

  I have a Java application that downloads information (Entities) from our server. I use a Download thread to download the data. The flow of the download process is as follows: Log in - The user entity is downloaded Based on the User Entity, download a 'Community' entities List and Display in drop down Based on Community drop down selection, Download and show 'Org Tree' in a JTree Based on Node selection, download Category entities and display in drop down Based on Category selection, download Sub Category entities and display in drop down Based on Sub Category selection download a large data set and save it The download occurs in a thread so the GUI does not 'freeze'. It also allows me to update a Progress Bar. I need help with managing this process. The main problem is when I download entity data I have to find a way to wait for the thread to finish before attempting to get the entity and move to the next step in the app flow. So far I have used a modal dialog to control flow. I start the thread, pop up a modal and then dispose of the modal when the thread is finished. The modal/thread are Observer/Observable the thread does a set changed when it is finished and the dialog disposes. Displaying a modal effectively stops the flow of the application so it can wait for the download to finish. I also tried just moving all the work flow to Observers. All relevant GUI in the process are Observers. Each update method waits for the download to finish and then calls the next piece of GUI which does its own downloading. So far I found these two methods produce code that is hard to follow. I would like to 'centralize' this work flow so other developers are not pulling out their hair when they try to follow it. My Question is: Do you have any suggestions/examples where a work flow such as this can be managed in a way that produces code that is easy to follow? I know 'easy' is a relative term and I know my both my options already work but I would like to get some ideas from other coders while I still have time to change it. Thank you very much.

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• Updating a deallocated UIWebView from a background thread

  - by Dan Ray

  As you can see from the title, I've programmed myself into a corner and I've got several things working against me... In a UIViewController subclass that manages a large and complex view. One part of it is a UIWebView that contains output from a web request that I had to build and execute, and manually assemble HTML from. Since it takes a second or two to run, I dropped it into the background by calling self performSelectorInBackground:. Then from that method I call there, I use self performSelectorOnMainThread: to get back to the surface of the thread stack to update the UIWebView with what I just got. Like this (which I've cut down to show only the relevant issues): -(void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { //then get mapquest directions NSLog(@"Got called to handle new location!"); [manager stopUpdatingLocation]; [self performSelectorInBackground:@selector(getDirectionsFromHere:) withObject:newLocation]; } - (void)getDirectionsFromHere:(CLLocation *)newLocation { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; CLLocationCoordinate2D here = newLocation.coordinate; // assemble a call to the MapQuest directions API in NSString *dirURL // ...cut for brevity NSLog(@"Query is %@", dirURL); NSString *response = [NSString stringWithContentsOfURL:[NSURL URLWithString:dirURL] encoding:NSUTF8StringEncoding error:NULL]; NSMutableString *directionsOutput = [[NSMutableString alloc] init]; // assemble response into an HTML table in NSString *directionsOutput // ...cut for brevity [self performSelectorOnMainThread:@selector(updateDirectionsWithHtml:) withObject:directionsOutput waitUntilDone:NO]; [directionsOutput release]; [pool drain]; [pool release]; } - (void)updateDirectionsWithHtml:(NSString *)directionsOutput { [self.directionsWebView loadHTMLString:directionsOutput baseURL:nil]; } This all works totally great, UNLESS I've backed out of this view controller before CLLocationManager hits its delegate method. If this happens after I've already left this view, I get: 2010-06-07 16:38:08.508 EverWondr[180:760b] bool _WebTryThreadLock(bool), 0x1b6830: Tried to obtain the web lock from a thread other than the main thread or the web thread. This may be a result of calling to UIKit from a secondary thread. Crashing now... Despite what this says, I can repeatably cause this crash when I back out too early. I'm not at all convinced that attempting a UI update from a background thread is really the issue; I think it's that my UIWebView is deallocated. I suspect that the fact I was just IN a background thread makes the runtime suspect something's up about that, but I feel fairly sure that's not it. So how do I tell CLLocationManager not to worry about it, when I'm backing out of that view? I tried [self.locationManager stopUpdatingLocation] inside my viewWillDisappear method, but that didn't do it. (Incidentally, MapQuest's apis are FANTASTIC. Way WAY better than anything Google provides. I can't recommend them highly enough.)

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• waiting for 2 different events in a single thread

  - by João Portela

  component A (in C++) - is blocked waiting for alarm signals (not relevant) and IO signals (1 udp socket). has one handler for each of these. component B (java) - has to receive the same information the component A udp socket receives. periodicaly gives instructions that should be sent through component A udp socket. How to join both components? it is strongly desirable that: the changes to attach component B to component A are minimal (its not my code and it is not very pleasent to mess with). the time taken by the new operations (usually communicating with component B) interfere very little with the usual processing time of component A - this means that if the operations are going to take a "some" time I would rather use a thread or something to do them. note: since component A receives udp packets more frequently that it has component B instructions to forward, if necessary, it can only forward the instructions (when available) from the IO handler. my initial ideia was to develop a component C (in C++) that would sit inside the component A code (is this called an adapter?) that when instanciated starts the java process and makes the necessary connections (that not so little overhead in the initialization is not a problem). It would have 2 stacks, one for the data to give component B (lets call it Bstack) and for the data to give component A (lets call it Astack). It would sit on its thread (lets call it new-thread) waiting for data to be available in Bstack to send it over udp, and listen on the udp socket to put data on the Astack. This means that the changes to component A are only: when it receives a new UDP packet put it on the Bstack, and if there is something on the Astack sent it over its UDP socket (I decided for this because this socket would only be used in the main thread). One of the problems is that I don't know how to wait for both of these events at the same time using only one thread. so my questions are: Do I really need to use the main thread to send the data over component A socket or can I do it from the new-thread? (I think the answer is no, but I'm not sure about race conditions on sockets) how to I wait for both events? boost::condition_variable or something similar seems the solution in the case of the stack and boost::asio::io_service io_service.run() seems like the thing to use for the socket. Is there any other alternative solution for this problem that I'm not aware of? Thanks for reading this long text but I really wanted you to understand the problem.

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• Thread class closing from other Class (Activity) with protected void onStop() Android

  - by user1761337

  I have a Problem with Closing the Thread. I will Closing the Thread with onStop,onPause and onDestroy. This is my Source in the Activity Class: @Override protected void onStop(){ super.onStop(); finish(); } @Override protected void onPause() { super.onPause(); finish(); } @Override public void onDestroy() { this.mWakeLock.release(); super.onDestroy(); } And the Thread Class: public class GameThread extends Thread { private SurfaceHolder mSurfaceHolder; private Handler mHandler; private Context mContext; private Paint mLinePaint; private Paint blackPaint; //for consistent rendering private long sleepTime; //amount of time to sleep for (in milliseconds) private long delay=1000/30; //state of game (Running or Paused). int state = 1; public final static int RUNNING = 1; public final static int PAUSED = 2; public final static int STOPED = 3; GameSurface gEngine; public GameThread(SurfaceHolder surfaceHolder, Context context, Handler handler,GameSurface gEngineS){ //data about the screen mSurfaceHolder = surfaceHolder; mHandler = handler; mContext = context; gEngine=gEngineS; } //This is the most important part of the code. It is invoked when the call to start() is //made from the SurfaceView class. It loops continuously until the game is finished or //the application is suspended. private long beforeTime; @Override public void run() { //UPDATE while (state==RUNNING) { Log.d("State","Thread is runnig"); //time before update beforeTime = System.nanoTime(); //This is where we update the game engine gEngine.Update(); //DRAW Canvas c = null; try { //lock canvas so nothing else can use it c = mSurfaceHolder.lockCanvas(null); synchronized (mSurfaceHolder) { //clear the screen with the black painter. //reset the canvas c.drawColor(Color.BLACK); //This is where we draw the game engine. gEngine.doDraw(c); } } finally { // do this in a finally so that if an exception is thrown // during the above, we don't leave the Surface in an // inconsistent state if (c != null) { mSurfaceHolder.unlockCanvasAndPost(c); } } this.sleepTime = delay-((System.nanoTime()-beforeTime)/1000000L); try { //actual sleep code if(sleepTime>0){ this.sleep(sleepTime); } } catch (InterruptedException ex) { Logger.getLogger(GameThread.class.getName()).log(Level.SEVERE, null, ex); } while (state==PAUSED){ Log.d("State","Thread is pausing"); try { this.sleep(1000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }} How i can close the Thread from Activity Class??

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• Signals and threads - good or bad design decision?

  - by Jens

  I have to write a program that performs highly computationally intensive calculations. The program might run for several days. The calculation can be separated easily in different threads without the need of shared data. I want a GUI or a web service that informs me of the current status. My current design uses BOOST::signals2 and BOOST::thread. It compiles and so far works as expected. If a thread finished one iteration and new data is available it calls a signal which is connected to a slot in the GUI class. My question(s): Is this combination of signals and threads a wise idea? I another forum somebody advised someone else not to "go down this road". Are there potential deadly pitfalls nearby that I failed to see? Is my expectation realistic that it will be "easy" to use my GUI class to provide a web interface or a QT, a VTK or a whatever window? Is there a more clever alternative (like other boost libs) that I overlooked? following code compiles with g++ -Wall -o main -lboost_thread-mt <filename>.cpp code follows: #include <boost/signals2.hpp> #include <boost/thread.hpp> #include <boost/bind.hpp> #include <iostream> #include <iterator> #include <string> using std::cout; using std::cerr; using std::string; /** * Called when a CalcThread finished a new bunch of data. */ boost::signals2::signal<void(string)> signal_new_data; /** * The whole data will be stored here. */ class DataCollector { typedef boost::mutex::scoped_lock scoped_lock; boost::mutex mutex; public: /** * Called by CalcThreads call the to store their data. */ void push(const string &s, const string &caller_name) { scoped_lock lock(mutex); _data.push_back(s); signal_new_data(caller_name); } /** * Output everything collected so far to std::out. */ void out() { typedef std::vector<string>::const_iterator iter; for (iter i = _data.begin(); i != _data.end(); ++i) cout << " " << *i << "\n"; } private: std::vector<string> _data; }; /** * Several of those can calculate stuff. * No data sharing needed. */ struct CalcThread { CalcThread(string name, DataCollector &datcol) : _name(name), _datcol(datcol) { } /** * Expensive algorithms will be implemented here. * @param num_results how many data sets are to be calculated by this thread. */ void operator()(int num_results) { for (int i = 1; i <= num_results; ++i) { std::stringstream s; s << "["; if (i == num_results) s << "LAST "; s << "DATA " << i << " from thread " << _name << "]"; _datcol.push(s.str(), _name); } } private: string _name; DataCollector &_datcol; }; /** * Maybe some VTK or QT or both will be used someday. */ class GuiClass { public: GuiClass(DataCollector &datcol) : _datcol(datcol) { } /** * If the GUI wants to present or at least count the data collected so far. * @param caller_name is the name of the thread whose data is new. */ void slot_data_changed(string caller_name) const { cout << "GuiClass knows: new data from " << caller_name << std::endl; } private: DataCollector & _datcol; }; int main() { DataCollector datcol; GuiClass mc(datcol); signal_new_data.connect(boost::bind(&GuiClass::slot_data_changed, &mc, _1)); CalcThread r1("A", datcol), r2("B", datcol), r3("C", datcol), r4("D", datcol), r5("E", datcol); boost::thread t1(r1, 3); boost::thread t2(r2, 1); boost::thread t3(r3, 2); boost::thread t4(r4, 2); boost::thread t5(r5, 3); t1.join(); t2.join(); t3.join(); t4.join(); t5.join(); datcol.out(); cout << "\nDone" << std::endl; return 0; }

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• ThreadPool.QueueUserWorkItem new Form CreateHanle Deadlock

  - by bogdanbrudiu

  I have a thread that needs to create a popup Window. I start the thread using ThreadPool.QueueUserWorkItem(new WaitCallback(CreatePopupinThread)) Thew thread creats a new form. The application freases in the new Form constructor at CreateHandle. The Worker Thread is locked... How can I fix this?

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