Java's Multi-Threading Foundation (2) consumer and producer relationships

1. Multiple threads Repeat a result as follows: It's sold out and the warehouse is full.

public class Productandconsumer {public static void main (string[] args) {Clerk Clerk = new Clerk (); Product Product = new product (clerk); Consumer Consumer = new Consumer (clerk), new thread (product), start (); new Thread (Consumer). Start ();} Class Clerk {private int goodsnumber = 0;public synchronized void get () {if (goodsnumber<=10) {System.out.println (" Item A stock quantity is: "+ ++goodsnumber);} Else{system.out.println ("The warehouse is full");}} Public synchronized void Sale () {if (goodsnumber>0) {System.out.println ("Item A inventory quantity is:" +--goodsnumber);} Else{system.out.println ("already sold Out");}}} Class Product implements Runnable{private clerk Clerk;public Product (clerk clerk) {This.clerk = clerk;} @Overridepublic void Run () {for (int i = 0; i <; i++) {Clerk.get ();}}} Class Consumer implements Runnable{private clerk Clerk;public Consumer (clerk clerk) {This.clerk = clerk;} @Overridepublic void Run () {for (int i = 0; i <; i++) {Clerk.sale ();}}} 

2. Multi-threaded synchronization lock caused by deadlock, as follows: Businessmen to find buyers first to money, buyers to find businessmen first to cause the deadlock, because: one does not release the lock, the other is not locked

public class Goodsandmoney {public static void main (string[] args) {Trader Trader = new Trader (Buyer.money); Buyer buyer = New Buyer (trader.goods); new Thread (Trader). Start (); new Thread (buyer). Start ();} Class Trader implements Runnable {public static string goods = "goods";p ublic static string Money;public Trader (String mon EY) {Trader.money = money;} @Overridepublic void Run () {while (true) {synchronized (goods) {synchronized (money) {}}system.out.println ("pay first ~ after delivery ~");} }class Buyer implements Runnable {public static string money = ' money ';p ublic static string Goods;public buyer (String good s) {buyer.goods = goods;} @Overridepublic void Run () {while (true) {synchronized (money) {try {Thread.Sleep ($)} catch (Interruptedexception e) {E . Printstacktrace ();} Synchronized (goods) {}}system.out.println ("first delivery ~ after paying ~");}}}

3. False wakeup, as follows: When the last occurrence is sold out, the selling thread is in the wait state, so the thread does not end

public class Productandconsumer {public static void main (string[] args) {Clerk clerk = new Clerk (); Product Product = new product (clerk); Consumer Consumer = new Consumer (clerk), new thread (product), start (); new Thread (Consumer). Start ();} Class Clerk {private int goodsnumber = 0;public synchronized void get () {if (goodsnumber<1) {System.out.println (" Commodity a inventory quantity is: "+ ++goodsnumber); This.notifyall ();} Else{system.out.println ("Warehouse is full"), try {this.wait ();} catch (Interruptedexception e) {e.printstacktrace ()}}} Public synchronized void Sale () {if (goodsnumber>0) {System.out.println ("Item A inventory quantity is:" +--goodsnumber); This.notifyall ();} Else{system.out.println ("Sold Out"), try {this.wait ();} catch (Interruptedexception e) {e.printstacktrace ();}}}} Class Product implements Runnable{private clerk Clerk;public Product (clerk clerk) {This.clerk = clerk;} @Overridepublic void Run () {for (int i = 0; i <; i++) {Clerk.get ();}}} Class Consumer implements Runnable{private clerk Clerk;public Consumer (clerk clerk) {THIS.CLerk = Clerk;} @Overridepublic void Run () {for (int i = 0; i <; i++) {Clerk.sale ();}}}

4. False wakeup, when a thread enters wait, it releases the thread's lock, the subsequent thread is likely to wait, and after it wakes up, two threads run out of range

Package Volatile1;public class Productandconsumer {public static void main (string[] args) {Clerk clerk = new Clerk (); Product Product = new product (clerk); Consumer Consumer = new Consumer (clerk); new Thread (product). Start (); new Thread (Consumer). Start (); new Thread (product). Start (); New Thread (consumer). Start ();}} Class Clerk {private int goodsnumber = 0;public synchronized void get () {if (Goodsnumber >= 5) {System.out.println ("Warehouse has "), try {this.wait ();} catch (Interruptedexception e) {e.printstacktrace ();}} SYSTEM.OUT.PRINTLN ("Commodity A Inventory Quantity:" + ++goodsnumber); This.notifyall ();} Public synchronized void Sale () {if (goodsnumber <= 0) {System.out.println ("sold Out"), try {this.wait ();} catch (Interrup Tedexception e) {e.printstacktrace ();} try {thread.sleep;} catch (Interruptedexception e) {e.printstacktrace ()}} SYSTEM.OUT.PRINTLN ("Commodity a stock Quantity:" +--goodsnumber); This.notifyall ();}} Class Product implements Runnable {private Clerk clerk;public Product (clerk clerk) {This.clerk = clerk;} @Overridepublic void Run () {for (int i = 0; i <; i++) {Clerk.get ();}}} Class Consumer implements Runnable {private Clerk clerk;public Consumer (clerk clerk) {This.clerk = clerk;} @Overridepublic void Run () {for (int i = 0; i <; i++) {Clerk.sale ();}}}

5. Adding a loop to the 4 code will resolve the spurious wake-up, as the wake-up will pass while the condition needs to be met to jump out, and the first time to the while value will change, so it will not appear full

Package Volatile1;public class Productandconsumer {public static void main (string[] args) {Clerk clerk = new Clerk (); Product Product = new product (clerk); Consumer Consumer = new Consumer (clerk); new Thread (product). Start (); new Thread (Consumer). Start (); new Thread (product). Start (); New Thread (consumer). Start ();}} Class Clerk {private int goodsnumber = 0;public synchronized void get () {while (Goodsnumber >= 5) {System.out.println (" The warehouse is full "); try {this.wait ();} catch (Interruptedexception e) {e.printstacktrace ()}} SYSTEM.OUT.PRINTLN ("Commodity A Inventory Quantity:" + ++goodsnumber); This.notifyall ();} Public synchronized void Sale () {goodsnumber <= 0) {System.out.println ("sold Out"), try {this.wait ();} catch (Inter Ruptedexception e) {e.printstacktrace ();} try {thread.sleep;} catch (Interruptedexception e) {e.printstacktrace ()}} SYSTEM.OUT.PRINTLN ("Commodity a stock Quantity:" +--goodsnumber); This.notifyall ();}} Class Product implements Runnable {private Clerk clerk;public Product (clerk clerk) {This.clerk = clerk;} @Overridepublic void Run () {for (int i = 0; i <; i++) {Clerk.get ();}}} Class Consumer implements Runnable {private Clerk clerk;public Consumer (clerk clerk) {This.clerk = clerk;} @Overridepublic void Run () {for (int i = 0; i <; i++) {Clerk.sale ();}}}

5.jdk1.5 later lock method to resolve the above problems

Package Volatile1;public class ProductAndConsumer2 {public static void main (string[] args) {Clerk clerk = new Clerk (); Product Product = new product (clerk); Consumer Consumer = new Consumer (clerk); new Thread (product). Start (); new Thread (Consumer). Start (); new Thread (product). Start (); New Thread (consumer). Start ();}} Class Clerk {private int goodsnumber = 0;public synchronized void get () {while (Goodsnumber >= 5) {System.out.println (" The warehouse is full "); try {this.wait ();} catch (Interruptedexception e) {e.printstacktrace ()}} SYSTEM.OUT.PRINTLN ("Commodity A Inventory Quantity:" + ++goodsnumber); This.notifyall ();} Public synchronized void Sale () {goodsnumber <= 0) {System.out.println ("sold Out"), try {this.wait ();} catch (Inter Ruptedexception e) {e.printstacktrace ();} try {thread.sleep;} catch (Interruptedexception e) {e.printstacktrace ()}} SYSTEM.OUT.PRINTLN ("Commodity a stock Quantity:" +--goodsnumber); This.notifyall ();}} Class Product implements Runnable {private Clerk clerk;public Product (clerk clerk) {This.clerk = clerk;} @Overridepublic void Run () {for (int i = 0; i <; i++) {Clerk.get ();}}} Class Consumer implements Runnable {private Clerk clerk;public Consumer (clerk clerk) {This.clerk = clerk;} @Overridepublic void Run () {for (int i = 0; i <; i++) {Clerk.sale ();}}}

　　

Java's Multi-Threading Foundation (2) consumer and producer relationships