I have the following update code in the ASP.NET MVC controller: [AcceptVerbs(HttpVerbs.Post)] public ActionResult Person(int id, FormCollection form) { var ctx = new DB_Entities(); // ObjectContext var person = ctx.Persons.Where(s => s.Id == id).FirstOrDefault(); TryUpdateModel(person, form.ToValueProvider()); ctx.SaveChanges(...
All, What should be the approach to writing a thread safe program. Given a problem statement, my perspective is: 1 > Start of with writing the code for a single threaded environment. 2 > Underline the fields which would need atomicity and replace with possible concurrent classes 3 > Underline the critical section and enclose them in...
package pkg_1; public class ExpOnWaitMethod extends Thread { static Double x = new Double(20); public static void main(String[] args) { ExpOnWaitMethod T1 = new ExpOnWaitMethod(); ExpOnWaitMethod T2 = new ExpOnWaitMethod(); T1.start(); T2.start(); } public void run() { Mag...
In Windows Phone 7 / Silverlight, is the following code safe or is it a race condition? //Snippet 1 foreach(var item in list) { Deployment.Current.Dispatcher.BeginInvoke( () => { foo(item); }); } Surely (?) this alternative is racy? //Snippet 2 Deployment.Current.Dispatcher.BeginInvoke( () => { foreach(var item in li...
I have my site running fine with a simple 'merb' command. I'd like to spawn multiple processes, or threads or whatever, so that a long DB request (or more often, a long PDF building request) doesn't hang everyone else on the server. I've tried to use "merb -c3", but receive an error saying Daemonized mode is not available. Any other ...
I have been completely puzzled by an issue I just came over in my Java application. When I attempt to run the code given below, Java raises a ConcurrentModificationException on the line that says "if ( this.vertexStore.get ( v ).addAll ( output ) )". I find this very strange considering this a completely single-threaded application, a...
Hi, I now primarily write in python, however I am looking for a language that is more thread friendly (not JAVA,C#,C or C++). Python's threads are good when they are IO bound but it's coming up short when I am doing something CPU intensive. Any ideas? Thanks, James ...
Code from Java concurrency in practice book Listing 8.1 Why is the code deadlocking? Is it because the rpt.call in main() is basically the same thread as that in Executors? Even if I use 10 thread for exec = Executors.newFixedThreadPool(10); it still deadlocks? public class ThreadDeadlock { ExecutorService exec = Executors.newSingle...
I'm writing a pseudo shell program which creates a child from a parent process. The parent process waits for the child to finish before continuing. My forking code looks something like this: if(fork()==0) { execvp(cmd, args); } else { int status = 0; wait(&status); printf("Child exited with status of %d\n", status); ...
In the concurrency runtime introduced in VS2010, there is a concurrent_queue class. It has a non blocking try_pop() function. Similar in Intel Thread Building Blocks (TBB), the blocking pop() call was removed when going from version 2.1 to 2.2. I wonder what the problem is with a blocking call. Why was it removed from TBB? And why is th...
Hi There, we are planning to use SQLite in our project , and bit confused with the concurrency model of it (because i read many different views on this in the community). so i am putting down my questions hoping to clear off my apprehension. we are planning to prepare all my statements during the application startup with multiple conn...
All, Recently I developed a code that supposedly is a thread-safe class. Now the reason I have said 'supposedly' is because even after using the sync'ed blocks, immutable data structures and concurrent classes, I was not able to test the code for some cases because of the thread scheduling environment of JVM. i.e. I only had test cases ...
Is it a good solution or not? How to implement? When should I shutdown properly? I shutdown it onDestroy() in the Activity, then relaunch my app as soon as possible. It causes a java.util.concurrent.RejectedExecutionException, why? Does anyone know its lifecycle? Any idea? Thanks. ...
I think in the implementation of ConcurrentHashMap, ReentrantLock has already been used. So there is no need to use ReentrantLock for the access of a ConcurrentHashMap object. And that will only add more synchronization overhead. Any comments? ...
Good morning. I'm having concurrency issues. I've created a WCF service, and I've tested it to make sure that individual calls work just fine. Now I'm performing some load testing, and I'm seeing super high CPU utilization with long wait times for requests to be completed. My load testing tool is just a console application configur...
I came across this really nice looking Scala code while researching XMPP for a .Net project we're working on: object Main { /** * @param args the command line arguments */ def main(args: Array[String]) :Unit = { new XMPPComponent( new ComponentConfig() { def secret() : String = { "secret.goes.here" ...
I have the need to persist a calculated property with an aggregate root. The calculation is based on child entities. I am using the root to add/remove the children via domain methods, and these methods update the calculate property. A child entity can be added to a particular root by multiple users of the system. For example, UserA can ...
And what happens when I try to spawn too many? I'm getting the following error when I spawn more than about 900 threads: terminate called after throwing an instance of 'dining 1 boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::thread_resource_error> >dining 3 ' dining 2 what(): dining 4 boost:...
If your response in Sinatra returns an 'eachable' object, Sinatra's event loop will 'each' your result and yield the results in a streaming fashion as the HTTP response. However, if there are concurrent requests to Sinatra, it will iterate through all the elements of one response before handling another request. If we have a cursor to ...
Normally Servlets are initiated just once and web container simple spawns a new thread for every user request. Let's say if I create my own web container from scratch and instead of Threads, I simply create Servlets as Singleton. Will I be missing anything here? I guess, in this case, the singleton can only service one user request at a ...