multithreading - Java how to limit number of threads acting on method -

i have java method in web application doing heavy file operation. thing is, if more 5 threads come simultaneously (which come in testing phase) breaks down. mean cannot handle heavy traffic.

that's why want handle maximum 5 requests @ time method if 6th request come wait until 1 of first 5 finished

public  synchronized void add(int value){       file a=new file("d:/heavyfile1");       file b=new file("d:/heavyfile2");       file c=new file("d:/heavyfile3");       //operation on file   } 

i have added synchronized keyword handles 1 request @ time leading performance issue every next thread have wait till finished. please me.

you can use executor.newfixedthreadpool idiom, internally execution logic.

full example below:

public class main {      public static void main(string[] args) throws exception {         main m = new main();         // simulating window of time method invoked continuously         (int = 0; < 11; i++) {             m.dosomething();         }         // shutting down executor when done         m.terminate();     }      executorservice executor = executors.newfixedthreadpool(5);      // internally submits new task executor     public void dosomething() {         executor.submit(new runnable() {             @override             public void run() {                 long wait = threadlocalrandom.current().nextlong(2000);                 try {                     system.out.printf(                         "%s sleeping %dms.%n",                          thread.currentthread().getname(),                          wait                     );                     thread.sleep(wait);                 }                 catch (interruptedexception ie) {                     // suppressed                 }                 system.out.printf(                     "%s doing something!%n",                      thread.currentthread().getname()                 );             }         });     }      public void terminate() throws exception {         executor.shutdown();     } } 

output

will vary, in lines of:

pool-1-thread-1 sleeping 1533ms. pool-1-thread-4 sleeping 784ms. pool-1-thread-3 sleeping 684ms. pool-1-thread-5 sleeping 1375ms. pool-1-thread-2 sleeping 1717ms. pool-1-thread-3 doing something! pool-1-thread-3 sleeping 1252ms. pool-1-thread-4 doing something! pool-1-thread-4 sleeping 301ms. pool-1-thread-4 doing something! pool-1-thread-4 sleeping 1140ms. pool-1-thread-5 doing something! pool-1-thread-5 sleeping 1454ms. pool-1-thread-1 doing something! pool-1-thread-1 sleeping 1594ms. pool-1-thread-2 doing something! pool-1-thread-2 sleeping 227ms. pool-1-thread-3 doing something! pool-1-thread-2 doing something! pool-1-thread-4 doing something! pool-1-thread-5 doing something! pool-1-thread-1 doing something! 

note

see re-used thread names, new submitted tasks assigned vacant thread in pool.