multithreading

问题 I would like to know what are ruby's alternatives to the Java methods : wait notify notifyAll Could you please post a small snippet or some links ? 回答1: With the caveat that I don't know Java, based on your comments, I think that you want a condition variable. Google for "Ruby condition variable" comes up with a bunch of useful pages. The first link I get, seems to be a nice quick introduction to condition vars in particular, while this looks like it gives a much broader coverage of threaded

问题 I would like to know what are ruby's alternatives to the Java methods : wait notify notifyAll Could you please post a small snippet or some links ? 回答1: With the caveat that I don't know Java, based on your comments, I think that you want a condition variable. Google for "Ruby condition variable" comes up with a bunch of useful pages. The first link I get, seems to be a nice quick introduction to condition vars in particular, while this looks like it gives a much broader coverage of threaded

问题 I have a snippet of code that change a counter in two threads. It's not thread safe because I didn't put any atomic variable or lock in the code. It gives the right result as I expected if the code only run once, but I want to run it for several times, so I put the code into a for loop. And the question is that only the first or the first two loops will generate the result I expect. For the rest of the loops, the results are always 0, which seems to be thread safe. Is there any inner operator

问题 I find that I am enjoying the simplicity of running code asynchronously through BackgroundWorkers. I have taught myself through example or trial and error on its uses, pitfalls, safe-threading etc., not so much the theory and perhaps my Achilles heel. I have done my reserach but one thing I don't find very much talk of, how can I effectively create and use a pool of BackgroundWorkers? Or what is a better alternative that is just as simple as using BWs? I will illustrate the problem I am

问题 I find that I am enjoying the simplicity of running code asynchronously through BackgroundWorkers. I have taught myself through example or trial and error on its uses, pitfalls, safe-threading etc., not so much the theory and perhaps my Achilles heel. I have done my reserach but one thing I don't find very much talk of, how can I effectively create and use a pool of BackgroundWorkers? Or what is a better alternative that is just as simple as using BWs? I will illustrate the problem I am

问题 I wonder that whether Thread.interrupt() and Thread.currentThread.interrupt() do the same thing or will give the same result? If not, what's the difference? The similar quesiton is: what's the difference between Thread.sleep() and Thread.currentThread.sleep() since they seems make the same sense? 回答1: The Thread.interrupt() method interrupts the specific Thread that the instance references to: Thread x = getSomeThreadInstance(); x.interrupt(); The x variable can refer to any thread instance.

问题 Some background on why I'm asking this. I asked this question a few hours ago When a goroutine blocks on I/O how does the scheduler identify that it has stopped blocking? which had the answer All I/O must be done through syscalls, and the way syscalls are implemented in Go, they are always called through code that is controlled by the runtime. This means that when you call a syscall, instead of just calling it directly (thus giving up control of the thread to the kernel), the runtime is

问题 I tried to run 100 Sleep tasks in parallel using Java8(1.8.0_172) stream.parallel() submitted inside a custom ForkJoinPool with 100+ threads available. Each task would sleep for 1s. I expected the whole work would finish after ~1s, given the 100 sleeps could be done in parallel. However I observe a runtime of 7s. @Test public void testParallelStream() throws Exception { final int REQUESTS = 100; ForkJoinPool forkJoinPool = null; try { // new ForkJoinPool(256): same results for all tried

问题 What happens to dangling threads in Java? Like if I create an application and it spawns multiple threads. And one of the threads does not finish and the main program finishes before that. What will happen to this dangling thread? Will it stay in the thread pool infinitely or JVM will kill the thread after a threshold time period??? 回答1: It depends on if the thread has been marked as "daemon" or not. Daemon threads will be killed when the JVM exits. If there are any threads that are not daemon

问题 I understand that with threadless async there are more threads available to service inputs (e.g. a HTTP request), but I don't understand how that doesn't potentially cause cause thread starvation when the async operations complete and a thread is needed to run their continuation. Let's say we only have 3 threads Thread 1 | Thread 2 | Thread 3 | and they get blocked on long-running operations that require threads (e.g. make database query on separate db server) Thread 1 | --- | Start servicing