Background:
When I tested the multi-production and multi-consumption operation values - suspended animation, there were two production and consumption threads respectively, and each thread looped the corresponding method twice.
Problem :
Print the log and found that consumption 2 has a wait before it wakes up Then it went down and executed, I don't know why?
Attach the test code
first . There is always
consumer 2 WAITING 0 in the log. Releasing value=null
Consumer 2 WAITING 1
Normal release of value is followed by value, but this time it does not. Although it does not affect the function, it is very strange.
/**
* 3.1.11.2 Multi-production and multi-consumption operation value - suspended animation
* Created by ironlee on 17/12/23.
*/
public class ProducerAndConsumerAllWait {
private String value;
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
/**
* Production
* @param lock
*/
public void producer(Object lock){
synchronized (lock){
try {
int i = 0 ;
while(StringUtils.isNotBlank(getValue())) {
System.out.println(Thread.currentThread().getName()+" WAITING value="+getValue()+" "+(i++));
lock.wait();
}
String value = System.currentTimeMillis()+"-"+System.nanoTime();
System.out.println(Thread.currentThread().getName()+" RUNNABLE value="+value);
setValue(value);
lock.notify();
// System.out.println(System.currentTimeMillis()+"-"+System.nanoTime()+" 生产者 "+Thread.currentThread().getName()+" NOTIFY value="+getValue());
} catch (InterruptedException e) {
e.printStackTrace ();
}
}
}
/**
* Consumption
* @param lock
*/
public void consumer(Object lock){
synchronized (lock){
try{
int i = 0 ;
// Why didn't wake up wait to go down?
while(StringUtils.isBlank(getValue())){
System.out.println(Thread.currentThread().getName()+" WAITING "+(i));
lock.wait();
System.out.println(Thread.currentThread().getName()+" WAITING "+(i) + " 解除 value="+getValue());
i++;
}
System.out.println(Thread.currentThread().getName()+" RUNNABLE value="+getValue());
setValue(null);
lock.notify();
// System.out.println(System.currentTimeMillis()+"-"+System.nanoTime()+" 消费者 "+Thread.currentThread().getName()+" NOTIFY value="+getValue());
}catch(InterruptedException e){
e.printStackTrace ();
}
}
}
public static void main(String[] args) {
final Object lock = new Object();
final ProducerAndConsumerAllWait domain = new ProducerAndConsumerAllWait();
final int count = 2;
Runnable producer = new Runnable() {
@Override
public void run() {
synchronized (lock){
int i = 0 ;
while( i < count ){
System.out.println( Thread.currentThread().getName()+" 序号="+i);
domain.producer( lock );
i++;
}
}
}
};
Runnable consumer = new Runnable() {
@Override
public void run() {
synchronized (lock){
int i = 0 ;
while(i< count){
System.out.println( Thread.currentThread().getName()+" 序号="+i);
domain.consumer( lock );
i++;
}
}
}
};
for (int ii = 0; ii <2; ii ++) {
Thread producerT = new Thread(producer);
producerT.setName("Producer"+(ii+1));
producerT.start ();
Thread consumerT = new Thread(consumer);
consumerT.setName("Consumer"+(ii+1));
consumerT.start();
}
try {
Thread.sleep( 1000L );
} catch (InterruptedException e) {
e.printStackTrace ();
}
Thread[] threadArray = new Thread[Thread.currentThread().getThreadGroup().activeCount()];
Thread.currentThread().getThreadGroup().enumerate( threadArray );
for( Thread t : threadArray ){
System.out.println( t.getName() + " " + t.getState() );
}
}
}