thread-safety

问题 Let's say I have this class: class Zoo { protected String bearName; protected Double trainerSalary; protected Integer monkeyCount; } Can one thread write to these fields, and another one read them, without requiring synchronized access to the Zoo object? Note: these values can be treated separate from one another, so it doesn't matter that the trainerSalary is changed while the monkeyCount is read. EDIT : Just to clarify, the fields are mutable ; only their referenced objects are immutable .

问题 So I have a singleton class that manages the current user that is logged into my application. It looks like this class SessionManager { static let shared = SessionManager() var loggedInUser: User? } The problem is that if I want to get that user object from a background thread, I can't as I get the following exception: 'RLMException', reason: 'Realm accessed from incorrect thread.' After some googling I found Thread Safe Reference's. So I changed my class to be something like this instead:

问题 I have multiple threads in my application accessing a BitSet concurrently. The documentation says: A BitSet is not safe for multithreaded use without external synchronization. It doesn't say if it is not safe for reading or writing. Can anybody explain. 回答1: A BitSet is only safe for read-only operations if there is a "happens before" relationship between the last action that initializes the BitSet and the actions that read it. The simplest way to achieve this is using a final . For example:

问题 I'm getting a deadlock in the Swing application I maintain, and although I have a workaround that appears to work, I'm not sure that I have understood what I am doing and haven't just hidden a race condition that may pop up again later. A thread trace shows the deadlock is occurring between two threads, AWT-EventQueue-0 and AWT-EventQueue-1. My first question is which if either of these is the infamous Event Dispatching Thread. Both threads have the following at the bottom of their stack

问题 I was trying examples from JCIP and Below program should not work but even if I execute it say 20 times it always work which means ready and number are becoming visible even if it should in this case public class NoVisibility { private static boolean ready; private static int number; private static class ReaderThread implements Runnable { public void run() { while (!ready) Thread.yield(); System.out.println(number); } } public static void main(String[] args) { System.out.println(Runtime

问题 Everyone says static initializers are thread-safe, but I'm worried about a particular detail. Let's say I have static class MyStaticClass { public static readonly object myField = MyOtherClass.GetNewObject(); } static class MyOtherClass { public static object GetNewObject() { /* arbitrary code that returns a new object */ } } Which of the following does C# guarantee, when MyStaticClass.myField is not yet initialized? If threads 1 and 2 try to access myField together (in that order),

问题 Everyone says static initializers are thread-safe, but I'm worried about a particular detail. Let's say I have static class MyStaticClass { public static readonly object myField = MyOtherClass.GetNewObject(); } static class MyOtherClass { public static object GetNewObject() { /* arbitrary code that returns a new object */ } } Which of the following does C# guarantee, when MyStaticClass.myField is not yet initialized? If threads 1 and 2 try to access myField together (in that order),

问题 This code: #include <iostream> #include <thread> #include <mutex> struct Singl{ Singl(Singl const&) = delete; Singl(Singl&&) = delete; inline static thread_local bool alive = true; Singl(){ std::cout << "Singl() " << std::this_thread::get_id() << std::endl; } ~Singl(){ std::cout << "~Singl() " << std::this_thread::get_id() << std::endl; alive = false; } }; static auto& singl(){ static thread_local Singl i; return i; } struct URef{ ~URef(){ const bool alive = singl().alive; std::cout << alive

问题 Is it safe to use the same Encoding object from different threads? By "using" I mean, calling Encoding.GetString() , Encoding.GetBytes() and write some XML with an XmlWriter (created by something like XmlWriter.Create(myStream, new XmlWriterSettings() { Encoding = myEncoding }) . The msdn site states that "Any instance members are not guaranteed to be thread safe". So, how can I safely write two XML documents concurrently? (thank you!!) 回答1: Yes, it should be safe to use the same Encoding

问题 I have used this tutorial them same way in my application: http://www.benmccann.com/hibernate-with-jpa-annotations-and-guice/ My app is JAX-RS web service which will receive many concurrent requests and make updates to database. GenericDAOImpl.java implementation: public class GenericDAOImpl<T> implements GenericDAO<T> { @Inject protected EntityManager entityManager; private Class<T> type; public GenericDAOImpl(){} public GenericDAOImpl(Class<T> type) { this.type = type; } @Override public