Java Reentrant getQueueLength() Method

The getQueueLength() method of ReentrantLock Class returns the number of threads waiting to get the lock. The value is approximate because the number of threads can change dynamically while traversing internal data structures. It is used to monitor the state.

Syntax

Parameter

No parameter is passed.

Returns

the estimated number of threads waiting for this lock

Throws

No Exception is thrown.

Example 1

 import java.util.concurrent.locks.ReentrantLock;
 
 public class ReentrantLockgetQueueLengthExample1  {
     public static void main(String[] args) {
  
            ReentrantLock lock=new ReentrantLock();
            MyRunnableClass90 myRnbl=new MyRunnableClass90(lock);
            new Thread(myRnbl,"Thread-1").start();
                        
     }
 }
    
 class MyRunnableClass90 implements Runnable{
     
     ReentrantLock lock;
     public MyRunnableClass90(ReentrantLock lock) { 
            this.lock=lock;
     }
     
     public void run(){
            int i;
            Thread t1 = new Thread();
            Thread t2 = new Thread();
            t1.holdsLock(t1);
            t2.holdsLock(t2);
    	 for(i=5;i<=10;i++) {
    		 if(i==7)
    		 {
            System.out.println(" getQueueLength = "+lock.getQueueLength()+"  ");
    		 }
    		 if(i==5)
           System.out.println(Thread.currentThread().getName()
                         +" has released the lock.");
            
           
    	 }
     }
 }

Test it Now

Output:

Thread-1 has released the lock.
 getQueueLength = 0

Example 2

 import java.util.concurrent.locks.ReentrantLock;
 
 public class ReentrantLockgetQueueLengthExample2 {
     public static void main(String[] args) {
  
            ReentrantLock lock=new ReentrantLock();
            MyRunnableClass10 myRnbl=new MyRunnableClass10(lock);
            new Thread(myRnbl,"ThreadA").start();
            new Thread(myRnbl,"ThreadB").start();
            new Thread(myRnbl,"ThreadC").start();
            
     }
 }
   
  class MyRunnableClass10 implements Runnable{
     
     ReentrantLock lock;
     public MyRunnableClass10(ReentrantLock lock) { 
            this.lock=lock;
     }
     
     public void run(){
            
           
            lock.lock();
  
            System.out.println(Thread.currentThread().getName()
                         +" has got the  lock.");
            
                   try {
					Thread.sleep(2000);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
           
            System.out.println("getQueueLength = "+lock.getQueueLength());
            
            lock.unlock();  
     }
 }

Test it Now

Output:

ThreadB has got the  lock.
getQueueLength = 2
ThreadA has got the  lock.
getQueueLength = 1
ThreadC has got the  lock.
getQueueLength = 0

Next TopicJava ReentrantLock

← prev next →

For Videos Join Our Youtube Channel: Join Now

Feedback

Send your Feedback to [email protected]

Help Others, Please Share

Learn Latest Tutorials

Splunk

SPSS

Swagger

Transact-SQL

Tumblr

ReactJS

Regex

Reinforcement Learning

R Programming

RxJS

React Native

Python Design Patterns

Python Pillow

Python Turtle

Keras

Preparation

Aptitude

Reasoning

Verbal Ability

Interview Questions

Company Questions

Trending Technologies

Artificial Intelligence

AWS

Selenium

Cloud Computing

Hadoop

ReactJS

Data Science

Angular 7

Blockchain

Git

Machine Learning

DevOps

B.Tech / MCA

DBMS

Data Structures

DAA

Operating System

Computer Network

Compiler Design

Computer Organization

Discrete Mathematics

Ethical Hacking

Computer Graphics

Software Engineering

Web Technology

Cyber Security

Automata

C Programming

C++

Java

.Net

Python

Programs

Control System

Data Mining

Data Warehouse

^{Like/Subscribe us for latest updates or newsletter}