guoguo11191的专栏

1.一个生产者和一个消费者。存在资源竞争情况：1)生产者和消费者同时访问fruit store的库存量，及同时修改库存量时，存在资源竞争。

细分这种资源竞争的情况，至少会有如下两种原因：1)当时fruit store库存为0时，还未成功执行this.curFruitNum++，，消费者发现fuilt store发现库存数量还是为0，无法购买产品；当fuilt store库存为100时，还未成功执行this.curFruitNum–，生产者发现库存量还是100，不再生产产品。这种资源竞争的情况，如果对于某一次临界值库存100或0判断，还未执行curF错误，还不算糟糕，虽然造成了某一次的判断错误，但并没有影响整体业务功能。2)还有一种极端的情况，生产者和消费者同时执行this.curFruitNum++和this.curFruitNum–，由于++和–非原子性操作，会导致结果和预期不同，这种情况会影响业务功能。

class FruitStore {public int curFruitNum = 0;public boolean increase(){if (curFruitNum < 100) {this.curFruitNum++;return true;}return false;}public boolean decrease(){if (curFruitNum > 0) {this.curFruitNum–;return true;}return false;}}class FruitWorkerTom implements Runnable {private FruitStore fruitStore;private int stockNum = 0;public FruitWorkerTom(FruitStore fruitStore){this.fruitStore = fruitStore;}public boolean stockFruit() {if (this.fruitStore.increase()){System.out.println("stock");return true;}return false;}@Overridepublic void run() {while (this.stockNum < 100) {if (this.stockFruit()) {this.stockNum++;Thread.yield();}}}}class FruitBuyerMary implements Runnable {private FruitStore fruitStore;private int buyNum = 0;public FruitBuyerMary(FruitStore fruitStore){this.fruitStore = fruitStore;}public boolean buyFruit() {if (this.fruitStore.decrease()) {System.out.println("buy");return true;}return false;}@Overridepublic void run() {while (this.buyNum < 100) {if (this.buyFruit()) {this.buyNum++;Thread.yield();}}}}public class MainThread {public static void main(String[] args) {FruitStore fruitStore = new FruitStore();Thread fruitWorkerTom = new Thread(new FruitWorkerTom(fruitStore));FruitWorkerTom.start();Thread fruitBuyerMary = new Thread(new FruitBuyerMary(fruitStore));FruitBuyerMary.start();try {fruitWorkerTom.join();fruitBuyerMary.join();} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}System.out.println(fruitStore.curFruitNum);}}

1.多个生产者和多个消费者。存在资源竞争情况：1)生产者和消费者同时访问fruit store的库存量，及同时修改库存量时，存在资源竞争。2)生产者和生产者同时访问fruit store的库存量，及同时修改库存量时，存在资源竞争。2)消费者和消费者同时访问fruit store的库存量，及同时修改库存量时，存在资源竞争。

class FruitStore {public int curFruitNum = 0;public boolean increase(){if (curFruitNum < 100000) {this.curFruitNum++;return true;}return false;}public boolean decrease(){if (curFruitNum > 0) {this.curFruitNum–;return true;}return false;}}class FruitWorkerTom implements Runnable {private FruitStore fruitStore;public int stockNum = 0;public FruitWorkerTom(FruitStore fruitStore){this.fruitStore = fruitStore;}public boolean stockFruit() {if (this.fruitStore.increase()){System.out.println("Tom stock");return true;}return false;}@Overridepublic void run() {while (this.stockNum < 10000) {if (this.stockFruit()) {this.stockNum++;System.out.println(this.stockNum);Thread.yield();}}}}class FruitWorkerBob implements Runnable {private FruitStore fruitStore;public int stockNum = 0;public FruitWorkerBob(FruitStore fruitStore){this.fruitStore = fruitStore;}public boolean stockFruit() {if (this.fruitStore.increase()){System.out.println("Bob stock");return true;}return false;}@Overridepublic void run() {while (this.stockNum < 10000) {if (this.stockFruit()) {this.stockNum++;System.out.println(this.stockNum);Thread.yield();}}}}class FruitBuyerMary implements Runnable {private FruitStore fruitStore;public int buyNum = 0;public FruitBuyerMary(FruitStore fruitStore){this.fruitStore = fruitStore;}public boolean buyFruit() {if (this.fruitStore.decrease()) {System.out.println("buy");return true;}return false;}@Overridepublic void run() {while (this.buyNum < 10000) {if (this.buyFruit()) {this.buyNum++;System.out.println(this.buyNum);Thread.yield();}}}}class FruitBuyerLucy implements Runnable {private FruitStore fruitStore;public int buyNum = 0;public FruitBuyerLucy(FruitStore fruitStore){this.fruitStore = fruitStore;}public boolean buyFruit() {if (this.fruitStore.decrease()) {System.out.println("buy");return true;}return false;}@Overridepublic void run() {while (this.buyNum < 10000) {if (this.buyFruit()) {this.buyNum++;System.out.println(this.buyNum);Thread.yield();}}}}public class MainThread {public static void main(String[] args) {FruitStore fruitStore = new FruitStore();Thread fruitWorkerTom = new Thread(new FruitWorkerTom(fruitStore));fruitWorkerTom.start();Thread fruitBuyerMary = new Thread(new FruitBuyerMary(fruitStore));fruitBuyerMary.start();Thread fruitWorkerBob= new Thread(new FruitWorkerBob(fruitStore));fruitWorkerBob.start();Thread fruitBuyerLucy = new Thread(new FruitBuyerLucy(fruitStore));fruitBuyerLucy.start();try {fruitWorkerTom.join();fruitBuyerMary.join();fruitWorkerBob.join();fruitBuyerLucy.join();} catch (InterruptedException e) {e.printStackTrace();}System.out.println(fruitStore.curFruitNum);}}

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