concurrency

问题 My Java Threads does not work independently, how to fix it? This is the initial main: Mechanics mechanics = new Mechanics(busShop, "Mechanic 1"); Mechanics mechanics2 = new Mechanics(busShop, "Mechanic 2"); Thread thMechanic = new Thread(mechanics); Thread thMehanic2 = new Thread(mechanics2); thMechanic.start(); thMehanic2.start(); No problem so far, work as expected, so the mechanics do this: public void run() { fixEngine(); } private void fixEngine() { while (true) { busShop.FixEngine

问题 My Java Threads does not work independently, how to fix it? This is the initial main: Mechanics mechanics = new Mechanics(busShop, "Mechanic 1"); Mechanics mechanics2 = new Mechanics(busShop, "Mechanic 2"); Thread thMechanic = new Thread(mechanics); Thread thMehanic2 = new Thread(mechanics2); thMechanic.start(); thMehanic2.start(); No problem so far, work as expected, so the mechanics do this: public void run() { fixEngine(); } private void fixEngine() { while (true) { busShop.FixEngine

问题 I'm trying to build a simple Golang/Appengine app which uses a channel to handle each http request. Reason is I want each request to perform a reasonable large in- memory calculation, and it's important that each request is performed in a thread- safe manner (ie calculations from concurrent requests don't get mixed). Essentially I need a synchronous queue which will only process one request at a time, and channels look like a natural fit. Is it possible to use Go's buffered channel as a

问题 I would like to test some variants of transaction concurrency in PostgreSQL and for that I need a script which would force two transaction to start at exactly the same time. Something that does not requires manual intervention ;) Any ideas? 回答1: You can homebrew this by taking a LOCK on a table, setting up your transactions, then releasing the lock by rolling back the transaction that got the lock. See this prior answer and its links for details on this approach. While I demonstrated it using

问题 I have question related with following code #include <atomic> #include <thread> #include <assert.h> std::atomic<bool> x, y; std::atomic<int> z; void write_x_then_y() { x.store(true, std::memory_order_relaxed); y.store(true, std::memory_order_relaxed); } void read_y_then_x() { while (!y.load(std::memory_order_acquire)); if (x.load(std::memory_order_acquire)) ++z; } int main() { x = false; y = false; z = 0; std::thread a(write_x_then_y); std::thread b(read_y_then_x); a.join(); b.join(); assert

问题 I'm brand new to Haskell and in messing around with a few samples I've got a problem where I can't stop the program. I'm using Windows 7 and using runhaskell from ght. Ctrl-c doesn't work so I have to resort to the task manager which is a bit of a pain. Instead of doing that how can I create a separate control thread that would wait until I typed q and then quit my Haskell application. The application I've got the problem with is of the format: main = do h <- connectTo server (PortNumber

问题 I'm brand new to Haskell and in messing around with a few samples I've got a problem where I can't stop the program. I'm using Windows 7 and using runhaskell from ght. Ctrl-c doesn't work so I have to resort to the task manager which is a bit of a pain. Instead of doing that how can I create a separate control thread that would wait until I typed q and then quit my Haskell application. The application I've got the problem with is of the format: main = do h <- connectTo server (PortNumber

问题 I am trying to understand the proper way of using Grand Central Dispatch (GCD) to implement concurrent read exclusive write model of controlling access to a resource. Suppose there is a NSMutableDictionary that is read a lot and once in awhile updated. What is the proper way of ensuring that reads always work with consistent state of the dictionary? Sure I can use a queue and serialize all read and write access to the dictionary, but that would unnecessarily serialize reads which should be

问题 What would be the most elegant way to implement a Win32 equivalent of WaitForMultipleObjects in Java (v6). A thread is sleeping until one of several events occur. When that happens, I want to process it and get back to sleep. No data is required, just an event. 回答1: It really depends what you want to do with it, but you could do something as simple as using the wait/notify methods or you could use the structures in the java.util.concurrency package. The latter would personally be my choice.

问题 For an object to be runnable, it needs to implement the Runnable interface or extend the Thread class, however, it does not seem that HttpServlet does any of these. How come HttpServlet can be threaded or have i mistaken? 回答1: The Servlet itself is not a thread. The container maintains one instance of the servlet class and each request (thread) calls the same servlet object. So the servlet instances is shared across threads. In pseudo code it may look like this: class ServerThread extends