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  1. JDK
  2. JDK-8184719

Implementation logic of wait(long timeout, int nanos) method in Object class is incorrect

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    • generic
    • generic

    Description

      FULL PRODUCT VERSION :
      all version

      ADDITIONAL OS VERSION INFORMATION :
      All OS

      A DESCRIPTION OF THE PROBLEM :
      In wait method you are expecting time in milliseconds and nanoseconds. but in case user pass 0 milliseconds and 1 nano seconds , ideally system should wait maximum 1 nanoseconds but according to current implementation, It'll wait maximum 1000000 nanoseconds.

      REGRESSION. Last worked in version 8u121

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      Pass 0 as first parameter and 1 in second parameter.

      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      Thread should wait maximum 1 nanoseconds but it'll wait max 1000000 nanoseconds. because inside wait method if nanoseconds b/w 0-999999 , you guys increasing milliseconds 1, that's not correct.

       if (nanos > 0) {
                  timeout++;
              }
      ACTUAL -
      Ideally system should wait max 1 nanoseconds.

      REPRODUCIBILITY :
      This bug can be reproduced always.

      ---------- BEGIN SOURCE ----------
      package org.vc.object;

      public class WaitTest {

      public static void main(String[] args) {
      Message msg = new Message("process it");
      MyWait waiter = new MyWait(msg);
              new Thread(waiter,"vikas waiter").start();
              
              MyWait waiter1 = new MyWait(msg);
              new Thread(waiter1, "vikas waiter 1").start();
      }

      }


      class MyWait implements Runnable{
          
          private Message msg;
          
          public MyWait(Message m){
              this.msg=m;
          }

          @Override
          public void run() {
              String name = Thread.currentThread().getName();
              synchronized (msg) {
                  try{
                      System.out.println(name+" waiting to get notified at time:"+System.currentTimeMillis());
                      msg.wait(0,1);
                  }catch(InterruptedException e){
                      e.printStackTrace();
                  }
                  System.out.println(name+" waiter thread got notified at time:"+System.currentTimeMillis());
                  System.out.println(name+" processed: "+msg.getMsg());
              }
          }

      }

      class Message {
          private String msg;
          
          public Message(String str){
              this.msg=str;
          }

          public String getMsg() {
              return msg;
          }

          public void setMsg(String str) {
              this.msg=str;
          }

      }
      ---------- END SOURCE ----------

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              rriggs Roger Riggs
              webbuggrp Webbug Group
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                Created:
                Updated:
                Resolved: