java-threads

As per the javadoc notify Wakes up a single thread that is waiting on this object's monitor. If any threads are waiting on this object, one of them is chosen to be awakened. The choice is arbitrary and occurs at the discretion of the implementation. A thread waits on an object's monitor by calling one of the wait methods. I want to know how notify achieve this behavior. On many sites I read it sends a signal but What does signal means here? Does notify sends a signal directly to first waiting thread or it sends a signal to thread scheduler? It does not send it to the first thread, but to any

I have a queue of running threads and would like to expose some of its data while it is executed, to monitor the process. ThreadPoolExecutor provides access to its queue and I can iterate through these objects to call my overridden toString() method, but these are only threads that are waiting for execution. Is there a way to access threads that are currently running to call my method? Or maybe there's a better approach for this task in general? To clarify a bit more about the purpose, here's some code of general idea: public class GetDataTask implements Runnable { private String pageNumber;

class Test { boolean isFirstThread = true; private synchronized void printer(int threadNo) { if(isFirstThread) { try { Thread.sleep(2000); } catch (InterruptedException e) { e.printStackTrace(); } } isFirstThread = false; System.out.println(threadNo); } public void starter() { new Thread(){ @Override() public void run() { printer(0); } }.start(); new Thread(){ @Override() public void run() { printer(1); } }.start(); new Thread(){ @Override() public void run() { printer(2); } }.start(); new Thread(){ @Override() public void run() { printer(3); } }.start(); } } In the above code, when i call

I'm trying to parse @Context UriInfo to another thread and do some task. But when i try to run it, it gives the error as Exception in thread "Thread-691" org.jboss.resteasy.spi.LoggableFailure: Unable to find contextual data of type: javax.ws.rs.core.UriInfo My code as follows @GET @Path("/thread") public void thread(@Context UriInfo url){ Runnable run = new Runnable() { @Override public void run() { System.out.println(">>>>>>>>>>>> " + url.getRequestUri().getQuery()); } }; Thread t = new Thread(run); t.start(); } How can I get the UriInfo to the new thread? Just make the UriInfo parameter

I have a code where 4 threads run at the same time. I want to wait until all these 4 threads will be finished. And only after that to continue the app flow. I tried two approaches: Thread#join() , this approach works as expected. The code, which comes after join() is executed only after all threads are finished. ExecutorService#shutdown() , this technique allows executing code, which comes after shutdown() even if not all threads are finished. Code sample: ExecutorService service = Executors.newFixedThreadPool(cpuCoresNum); for (int i = 0; i < cpuCoresNum; i++) { service.submit(() -> { try {

When profiling my application I came across a weird behavior - the DestroyJavaVM thread is ALWAYS running - 100% of the time. After doing a little research on the subject, on which there's hardly any valuable information online, all I understood is that this thread is supposed to unload the JVM upon exit . If that's the case, why is this thread in RUNNING state 100% of the time from the very first moment I start my application? Doesn't it consume valuable resources and therefore may cause an OutOfMemoryError (like I sometimes get)? Is there any official reference to what this thread actually