Java keep main thread alive. From the Java Language Specification, 12.

Java keep main thread alive Java - Socket getKeepAlive() Method - Learn Java in simple steps starting from beginners to advanced concepts. Also, you will need to reset the JavaScript timeout when your ajax response is received to start the timer again. IOException; import java. I have used the addShutdownHook method to register a shutdown hook. Such queue is implemented using LinkedBlockingQueue and the behavior is as follows (source Spring Framework 5. Feb 23, 2025 · 文章浏览阅读205次。(x)=Arguments输入虚拟机启动参数-Xmx400m。_eclipse启动项目 exception in thread "keep-alive-timer" java. Some threads are daemon, some not. X reference documentation: 7. After I have run: shutdown. 2. Not correct. 3. If you have multiple active sequences you get multiple IO Scheduler threads. Mar 10, 2013 · The JVM doesn't stay alive unless a non-daemon thread is continuing to run, and this won't occur unless the coder explicitly or implicitly (such as running a Swing GUI) creates one or somehow keeps the main non-daemon thread alive (such as with a while loop). Thread. Nov 23, 2021 · I'm trying to create 10 threads for our Java application and keep them alive all the time. exit(-1),my main thread be closed. I can do this by using sendStream. Introduction We can use isAlive() from Thread to check if a thread is running. Looper is designed to keep the thread alive even when there are no tasks. Active threads take up residency in the runnable thread pool. Sample Source Code's of classes java. Syntax thread_object. the new thread will call some method in other . In the example below, two print(f'') statements are written to show calls to thread. A thread which is just sleeping or waiting hasn't died (it hasn't exited its run method, either normally or abruptly), so isAlive will return true. Using a non Apr 17, 2017 · 之前讲到Thread的创建，那是Thread生命周期的第一步，其后就是通过start()方法来启动Thread，它会执行一些内部的管理工作然后调用Thread的run()方法，此时该Thread就是alive(活跃)的，而且我们还可以通过isAlive()方法来确定该线程是否启动还是终结。 May 11, 2018 · So yes, a non-daemon thread running prevents the JVM from shutting down, and as long as the JVM is alive it won't force daemon threads to terminate. Or just call wait on an object. Reload to refresh your session. I would actually prefer the boolean approach so there is no way that the main thread could start the other thread twice - there may be a short delay until your Thread is up and running, and if your main thread tries to start the thread twice in Aug 10, 2011 · I am thinking of sending a "keep alive packet" by simply sending "#KEEP-ALIVE" to the other end. . e. AbstractList. For example, a thread Oct 30, 2020 · Suppose my thread is exhausted it reached maximum size of 15 and some more tasks are provided to the thread, some of my thread will be 30 seconds sleep state This can happen. Threads need to communicate with each other. exit(0) All exit, main exit:- If you want main thread to wait until all threads are finished use Thread. Alive是指已启动但尚未终止的线程。 调用run方法时，线程将运行一段特定时间，之后停止执行。 语法finalBooleanisAlive()如果调用该函数的线程正在运行且尚未终止，则上述代码返回true。 May 7, 2013 · if your long running thread is not a daemon thread, it will not get terminated once the main thread exits. Thread and sun. Apr 7, 2015 · This will make the server think you are still active and should keep the server session alive by resetting it. join() Aug 29, 2012 · For now I've had to add Thread. Assuming that all the connections are up, the five threads wil beome ready again shortly after to process the echo from the peer. In this article, we will learn the main differences between Thread. start() and Thread. final boolean isAlive() The isAlive() method returns true if the thread upon which it is called is still running. 8 Program Exit: A program terminates all its activity and exits when one of two things happens: All the threads that are not daemon threads terminate. Your support could be the lifeline that keeps this passion Feb 9, 2012 · NEW - A thread that has not yet started is in this state. package java. Jul 4, 2010 · Here is a sample I wrote for another post that allows you to gave a Thread Pool on another Thread that you can post messages to. My service prints log messages every second in a parallel thread. Java - Socket setKeepAlive() Method - Learn Java in simple steps starting from beginners to advanced concepts. This is a deadlock situation, because the main thread can never finish while waiting for itself. The JVM does not exit because there is still a user thread (the main thread) alive. The problem is that after my javax. Otherwise it can be garbage-collected, which unexports it, which allows all the stubs in it to be GC'd, which allows the remote objects they refer to to be DGC'd, which unexports them, which allows the RMI accept threads to exit, which allows the JVM to exit. Jul 23, 2023 · Logic is very simple. outofmemory Thread is "Alive" means that Thread is still running. 1 (and later versions) is essential for controlling the lifecycle of threads in relation to the JVM's termination. 4. The code finishes normally (i. print("#KEEP-ALIVE"). No matter what I do it remakes the connection even though HttpClient is by default persistent. In this Keep-Alive Connection Example, we send Connection and Keep-Alive headers to the ReqBin echo URL. You could share a CyclicBarrier object among your RaceCars and your main thread, and have the RaceCar threads invoke await() as soon as they are done with their task. main. Java - Wait for multiple threads to complete. The JVM continues to run threads until the exit method of Runtime is called (and permitted to run) or all non-daemon threads have died. BLOCKED - A thread that is blocked waiting for a monitor lock is in this state. server keep in memory the file name and client id 5. my implementation looks like this: //Main Dec 5, 2024 · Understanding Kafka Broker Configurations: Broker IDs, Listeners, Zookeeper, and Auto Topic… Mar 19, 2017 · (as they are meant to keep the threads alive) Further clarification of intent: each thread is an upload of a file, and I have another process that modifies files, but it waits for the file to not have any uploads. client open main socket 2. Feb 21, 2011 · It can be done using thread. By marking The allowCoreThreadTimeOut() method is used to allow or disallow core threads to time out and terminate when no tasks are available within the keep-alive time. Once done, they get back into the pool ready to be reused by another sequence. Background threads may end before the main thread, or after the main thread. currentThread()方法的线程就是main线程。 Jun 1, 2016 · It has Connection:keep-alive. if the pool has more than corePoolSize threads and all are busy, kick off a new thread for a new task until maxPoolSize is reached. import java. It is a thread that has left the "new" state and has attained (or re-attained) the "runnable" state. The main() code runs in a thread. The isAlive() method returns true if the thread upon which it is called is still running. PS: You don't really need to do anything in the backend controller, you are just poking the session to keep it alive. Therefore, to keep threads alive after the main method exits, you need to use daemon threads or prevent the application from exiting by leveraging certain synchronization mechanisms. server open the main socket and assign a client id 3. However, this is hardly a satisfactory solution, and it also raises a larger question: How can one thread know when another thread has ended? Oct 22, 2013 · I have declared the thread as setDaemon(false) but it terminates with the calling methods termination. You can enumerate all the threads in the JVM, but it has a code 'smell' to me if you have to do that for proper function of your program. keep-alive. isAlive() has the following syntax. After the main thread finishes, the JVM exits, and the daemon thread is terminated abruptly. RUNNABLE - A thread executing in the Java virtual machine is in this state. run() MethodThread. by joining each of the threads. Code: while (true) { . Sep 17, 2019 · I wanted to created a program to calculate average of the numbers input through console using threading in java. Thread-1 is alive: true Thread-2 is alive: true Thread-1 is alive: true Thread-2 is alive: true Thread-1 is alive: false Thread-2 is alive: false Both threads have finished. Jun 3, 2022 · The . My code is as follows: import com. I added some documentation around that, too. In Java, when the main method completes its execution, the Java Virtual Machine (JVM) terminates unless there are non-daemon threads still running. Before starting, is Thread-1 alive? false After starting, is Thread-1 alive? true Thread-1 is running. The application is It's still alive, just not running. How to check if current thread is not main thread. Deamon threads are automatically closed when your main method finishes. Infinite Loop: The thread runs within a while (running) loop, which keeps it alive as long as running is true. httpserver. subList(AbstractList. Uhwell, if it's not alive it does not even run, does it? Or it isn't even born in the first place So, what does the javadoc want to say here? Feb 6, 2016 · 文章浏览阅读2k次。在Eclipse中运行Tomcat发生OutOfMemoryError: PermGen space错误现象：Exception in thread "Keep-Alive-Timer" java. May 9, 2022 · Thread class in java provides numerous methods that are very essential in order to understand the working of threads as the thread stages are triggered by them. It returns false otherwise. I think that you don't understand my problem: the problem isn't read a message from the queue, the problem is find a way to keep the receiver alive ( also when the main program ends ) to listen to the queue. From the Java Language Specification, 12. Dec 24, 2014 · Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand Jan 17, 2020 · But OP's scenario must be doing something different such that the threads end up with "daemon true", which led to attempts to keep the main thread alive indefinitely with while (true);. However, I mostly use Windows and have NOT Mar 8, 2023 · I have a Java application running inside Docker containers in Kubernetes. Dec 14, 2018 · As the documentation of Thread mentions, non-daemon threads will keep the JVM alive. Nov 18, 2010 · I have a java jar file which I am executing from the windows command prompt. Oct 5, 2023 · There's now the property spring. The main thread will proceed when all RaceCars have finished. So when they are kept alive it locks that process. Running Flag: A volatile boolean running variable is used to control the lifecycle of the thread. Only when all threads are done the process will terminate. Waits at most millis milliseconds for this thread to die May 2, 2018 · My application has a service which needs to stay alive even after the user closes it (by swiping it away). Aug 1, 2016 · The main problem is that this microservice create a ton of CLOSE_WAIT socket connections. When a Java Virtual Machine starts up, there is usually a single non-daemon thread (which typically calls the method named main of some designated class). Real-World Use Case Thread Monitoring and Cleanup Aug 2, 2018 · You mistake the purpose of the persistent connection. Its general form is shown here: final boolean isAlive() . It reads one request and sends one response, then it returns, closing the socket. Since it only uses core pools this also means keep alive time is irrelevant. Any other threads that you create in main() (or in other threads) run under the same process. Dec 28, 2016 · Until the associated sequence terminates or gets unsubscribed, that thread backing the worker is alive. Threads that wait this amount of time without processing a task will be terminated if there are more than the core number of threads currently in the pool, or if this pool #allowsCoreThreadTimeOut() allows core thread timeout. Example of Thread. isAlive() Program(Save as Apr 14, 2012 · Main Thread: 5 My Thread: 5 Main Thread: 4 My Thread: 4 My Thread: 3 Main Thread: 3 My Thread: 2 Main Thread: 2 My Thread: 1 Main Thread: 1 My Thread is alive My Thread is dead ధన్యవాదాలు (Thanks) Jan 12, 2012 · I have multithread web application running in Eclipse embedded Tomcat. You signed out in another tab or window. Aug 17, 2018 · 我们知道当一个Java程序启动以后，有一个线程就会立马跑起来，这就是通常所说的Main线程，main线程将会执行java的入口方法main方法，所以当前正在执行Thread. start() vs Thread. isAlive(). client request the send of a new file 4. I'm not sure though, why you would want to keep an application alive, if it's not doing anything anymore. Mar 25, 2024 · Your server does not support keep alive. Apr 26, 2014 · A thread interruption ignored because a thread was not alive at the time of the interrupt will be reflected by this method returning false. Is there a better way of doing this? If not, is there an efficient way of checking if you got the packet? Or something already there that allows you to check if the other end is alive? Oct 30, 2015 · You can create and start a thread. The simple java threading approach using the main loop to check . client open a new thread to send the file Aug 30, 2012 · Leaving the main method in Java does not automatically end the program. Click Send to execute the Keep-Alive Connection example online and see the results. Allowing core threads to time out can help reduce resource consumption in scenarios where threads are idle for extended periods. The java. The Java Virtual Machine continues to execute threads until either of the following occurs: Nov 18, 2010 · I have a java jar file which I am executing from the windows command prompt. If set to true, it will spawn a non-daemon platform thread which keeps the JVM alive. Jun 20, 2020 · How to check if the main thread is alive and running in a Console based java Application program. ( Server ) 2) Create another TCP socket that will connect to the first TCP socket I have cr Sep 18, 2020 · This code works only if there is already a message in the queue. Jul 8, 2010 · By one line I mean at most 100 chars per line. is_alive(): If the first thread hasn't finished storing the data before the other thread tries to read it, it's going to cause a problem. You switched accounts on another tab or window. One thread gets to know when another thread has ended. Sets the thread keep-alive time, which is the amount of time that threads may remain idle before being terminated. *; import java. Of course it's very easy to test this: Nov 29, 2024 · Java 线程池的keep alive机制 引言. This will cause the main thread to terminate eventually and the application will stop running. VM. run() in Java. Alternatively, just use a boolean flag and set it to true right before you start your thread. Oct 15, 2015 · What I want to do is: 1) Create a TCP socket listening to a particular port number in my local machine. In the main function I never get the output of the average value from the function May 9, 2022 · In Java's multi-threading concept, start() and run() are the two most important methods. Apr 10, 2013 · 1. Conclusion The setDaemon method in Java 1. On JVM I will prefer using Scala for modelling actors. The main thread calls join() on itself, which means it waits for itself to finish. run() method starts until just after it finishes. server send response authorizing the client to send the file 6. UI thread in Android has it's own Looper by default. Oct 29, 2018 · Additionally, it is almost never a good idea to set corePoolSize to zero or use allowCoreThreadTimeOut because this may leave the pool without threads to handle tasks once they become eligible to run. Main exit, all exit:- To make sure you end all child threads before main returns use System. Apr 22, 2013 · You could also try setting up the server socket in a daemon thread, but I suspect that this won't work as the blocking operation of the server socket probably won't Oct 18, 2011 · Have a static container in your main class that you put a reference to the objects in. So my example is explicit about making the call – setDaemon(false) – to make it clear how to get the correct result. This thread is stopped if the context is closed. join( );. Moreover, isAlive() method is used to know if the Thread is still running. util. 3. Then you'll always have a reference to the object, and it won't be reclaimed. Feb 4, 2014 · A thread is alive if it has been started and has not yet died. From the documentation: Tests if this thread is alive. sun. It can be a Map , List , whatever. no explicit call to java "join_thread" is required. The tasks I'm trying to assign them are the file downloads, report downloads, and PDF downloads. Jun 29, 2011 · I'm trying to create a http server in Java which is capable of providing keep-alive connections. In your test, you send one request and you're trying to provide an unlimited length response body. The main thread ends when it has no more work to do. It allows you to make multiple requests and get multiple responses over one connection. does what it is supposed to) but the java process continues to run. *; public class Konsep { String status; static String Sep 23, 2018 · My Spring Boot application is quite small and has one job: Act as a client by opening a websocket connection to a third-party website and listen for messages. Thread Class: We create a class ListenerThread extending Thread. 1605. Mar 4, 2016 · To keep it alive, don't return. jsch. isAlive() Syntax. Sep 23, 2018 · My Spring Boot application is quite small and has one job: Act as a client by opening a websocket connection to a third-party website and listen for messages. misc. java:484_exception in thread "keep-alive-timer" java. Yes, you can say that run() method is executing for the Alive Thread. To use keep alive the server needs to make sure it reads everything the client sends (to make room for the next request) and loop as long as there are no errors, reading new requests on the same connection. 464. Construct the barrier with the number of RaceCar threads plus one (for the main thread). By default the only non-daemon thread is the main thread and it ends when you leave the main method, therefore stopping the JVM. Java - How to wait for all threads to finish ? Jul 4, 2010 · Here is a sample I wrote for another post that allows you to gave a Thread Pool on another Thread that you can post messages to. OutOfMemoryError: PermGen space at java. While isAlive( ) is useful, you can use join() to wait for a thread to finish, shown here: Sep 9, 2014 · If the thread dies, the ThreadLocal will be cleaned up automatically since it's a class variable for the Thread. Iteration: 0 Thread-1 is running. 2. The main thread registers callback listeners that are run in separate threads. createRegistry() into needs to be static. Sep 8, 2007 · Sometimes this is accomplished by calling sleep() within main(), with a long enough delay to ensure that all child threads terminate prior to the main thread. stopProcessing(); line in main. Jan 18, 2022 · You signed in with another tab or window. A thread is alive if it has been started and has not yet died. Mar 3, 2013 · I'm not looking for anybody to diagnose my problem, I just want a way to force the Camel route to stay alive, because what I believe is happening is that the main Camel thread is reaching the end of the route, stopping it, and shutting down the application. The JVM exists if no more non-daemon threads are running. Sep 12, 2013 · A thread runs "under" a process. Create a while loop inside main() thread which waits for every 2 seconds and prints latest timestamp in console. These 10 threads should be alive all the time and run the tasks I assign to them. Please tell me how to keep that thread alive and also please throw some light on how to implement the Spring TaskExecutor to achieve same. There are multiple ways. in java, the default is that thread that was invoked will stay alive. Java multi-threading provides two ways to find with the help of isAlive() and join() method. Although it does return Mar 16, 2013 · the normal behavior is that if a thread is started and did't "join_thread" from main() it will be terminated when main done running. I would like to introduce a graceful shutdown of the application when Kubernetes sends a SIGTERM signal to the container and keep all the threads alive while the shutdown hook is running. The main() creates the Threads and also allows you to stop the Thread when you want. lang. However, since essentially daemon threads are Java Thread's, which presumably rely on running on JVM to achieve its functionalities, how do daemon threads even survive if JVM exits before the daemon thread finishes? Dec 9, 2022 · The servers inform the clients about persistent connections by including the "Connection: keep-alive" header in the server response. isAlive() method tests whether a thread is alive or not. is_alive() This method will return True from when the . jcraft. 在Java中，线程池是一种重要的并发处理模型，能够有效管理多个线程的生命周期，提高应用的性能和资源利用率。在使用线程池时，了解线程的keep alive机制至关重要。本文将介绍Java线程池的keep alive机制，并提供代码示例，帮助 Mar 3, 2018 · Looper is a thing that loops in a given thread and handles incoming messages, when there are no tasks it's looping and waiting for new tasks, so, answering your last question, the thread will not be suspended. For Java you can use libraries like Kilim. my implementation looks like this: //Main Mar 17, 2014 · Assuming that rt is a Thread, just check rt. Remarks. Is there a way to send a request without creating a new connection. start()Thread. Jan 3, 2018 · The Registry that you store the result of LocateRegistry. The application is Apr 21, 2013 · I'm writing Java GUI program for static route management using SSH. After main exits, the other threads are still running. So, that's about ten threads/sec need to run to support the keep-alives. lang; public class Thread implements Runnable { public final native boolean isAlive(); // Java thread status value zero corresponds to state "NEW" - 'not yet started'. io. This method returns a boolean value, true if the thread is still running and not finished, else false if a thread has not yet begun executing or has terminated. jar file, so I can't modify it. In that case, reject the task; keep corePoolSize number of threads alive even if they are idling, excess threads will die if they have been idle for more than keepAliveTime Apr 21, 2015 · The documentation of isAlive() says:. notify() when it finishes (or shutdown) would get the job done. Let us do depict stages of the Main Thread: The main thread sleeps for 5 seconds, allowing the daemon thread to run. Oct 22, 2014 · main itself is a thread. Dec 17, 2020 · The user threads started by main thread will complete execution at some point in time and terminate. Example. (I basically need this to keep the program alive. Thread. Java Thread. It should be possible to let your main() thread exit WITHOUT waiting to join other threads that are currently running under the same process. How to round a number to n decimal places in Java. How can I handle the exit code and keep the main thread alive? PS. To stop main from finishing just eliminate the processor. WAITING - A thread that is waiting indefinitely for another thread to perform a particular action is in this state. The Java code was The isAlive( ) method returns true if the thread upon which it is called is still running. See this post for a comparison of Actor model related libraries in Java. bat I see that some threads finished work, but some remain! St Apr 28, 2012 · An active java thread is a thread that is eligible to be the currently running thread of execution. sleep(4000) into to my unit test to make sure that Spring context is not killed off from under the test before the spawned extra threads have a change to finish their work and give return values back to the main thread. Iteration: 4 After finishing, is Thread-1 alive? false Explanation: Jul 6, 2015 · I am reading docs about Java's setDaemon() method, and got confused when I read that JVM exits without waiting for daemon threads to finish. 4. is_alive() method returns True if the thread is still running and False, otherwise. Have a look. Iteration: 1 Thread-1 is running. I'm using the com. wait() and the end of the camel route thread to signal . Iteration: 2 Thread-1 is running. Jun 6, 2010 · As a bonus, by modelling the scenario as actors you get rid of explicit manipulation of threads, synchronization and locking. HttpServer class. By default, core threads are not allowed to time out. May 11, 2012 · Assuming that a keep-alive is sent every 2 minutes, 120 seconds, that means about 5 threads becoming ready per second to send a keep-alive. The documentation of join() says:. Apr 11, 2013 · My main thread created a new thread And when the new thread call System. outofmemoryerror: permgen s Apr 30, 2023 · This creates a chain of daemon threads that keep creating new threads. net. It is also answered here already. This tutorial will teach you concepts like Java Syntax, Variable Types, Data Types, Type Casting, Operators, Loops, Decision Making, Function, OOPs, File Handling, Errors & Exceptions, Multi-threading etc. I'd like to force the main Camel thread to stay alive for, say, 60 seconds, to see if I Oct 22, 2018 · At the very minimum you need a main thread to kick off a thread to run the camel route and then check for when that thread is done. Iteration: 3 Thread-1 is running. However non-deamon threads will keep your application alive until they are finished. run()Creates a new thread and the run() method is ex Jun 20, 2020 · How to check if the main thread is alive and running in a Console based java Application program. Would anyone have some better ideas on how to make this test implementastion smarter? tester: Oct 30, 2020 · Suppose my thread is exhausted it reached maximum size of 15 and some more tasks are provided to the thread, some of my thread will be 30 seconds sleep state This can happen. I understand that the whole concept of "KEEP-ALIVE" shall keep the connection open until I close it, but it's possible that the server will drop the connection for some reasons and creates this CLOSE_WAIT socket. icltd imtuzy ppgldd agax uursmep ejzy ywrkz nkkk bejkcm omkhbt efm ruuzh akewbw bxbgp bvipy