C# Producer/Consumer pattern
c#, producer-consumer
Solution
First, I can't reproduce your problem, here both threads consume some of the items. I guess your machine is faster but adding Sleep like gw suggest will solve that. What I would also suggest is that you don't try to sync the producer, I mean let it queue items as fast as it can and let the consumers sync to see who handles each item. I made a quick modification and it seems to be working fine:
static void Main()
{
Object lockObj = new object();
Queue<string> queue = new Queue<string>();
Producer p = new Producer(queue);
Comsumer c1 = new Comsumer(queue, lockObj, "c1");
Comsumer c2 = new Comsumer(queue, lockObj, "c2");
Thread t1 = new Thread(c1.consume);
Thread t2 = new Thread(c2.consume);
t1.Start();
t2.Start();
Thread t = new Thread(p.produce);
t.Start();
Console.ReadLine();
}
}
public class Producer
{
Queue<string> queue;
static int seq;
public Producer(Queue<string> queue)
{
this.queue = queue;
}
public void produce()
{
while (seq++ < 1000) //just testinng 15 items
{
string item = "item" + seq;
queue.Enqueue(item);
Console.WriteLine("Producing {0}", item);
}
}
}
public class Comsumer
{
Queue<string> queue;
Object lockObject;
string name;
public Comsumer(Queue<string> queue, Object lockObject, string name)
{
this.queue = queue;
this.lockObject = lockObject;
this.name = name;
}
public void consume()
{
string item;
while (true)
{
lock (lockObject)
{
if (queue.Count == 0)
{
continue;
}
item = queue.Dequeue();
Console.WriteLine(" {0} Comsuming {1}", name, item);
}
}
}
}
You may also add the sleep to slow down the consumer loops.
Problem
I have simple one-producer/two-consumers code as follows but the output shows that only `C2` is consuming. Are there any bugs in my code? ``` class Program { static void Main(string[] args) { Object lockObj = new object(); Queue<string> queue = new Queue<string>(); Producer p = new Producer(queue, lockObj); Consumer c1 = new Consumer(queue, lockObj, "c1"); Consumer c2 = new Consumer(queue, lockObj, "c2"); Thread t1 = new Thread(c1.consume); Thread t2 = new Thread(c2.consume); t1.Start(); t2.Start(); Thread t = new Thread(p.produce); t.Start(); Console.ReadLine(); } } public class Producer { Queue<string> queue; Object lockObject; static int seq = 0; public Producer(Queue<string> queue, Object lockObject) { this.queue = queue; this.lockObject = lockObject; } public void produce() { while( seq++ <15) //just testinng 15 items { lock (lockObject) { string item = "item" + seq; queue.Enqueue(item); Console.WriteLine("Producing {0}", item); if (queue.Count == 1) { // first Monitor.PulseAll(lockObject); } } } } } public class Consumer { Queue<string> queue; Object lockObject; string name; public Consumer(Queue<string> queue, Object lockObject, string name) { this.queue = queue; this.lockObject = lockObject; this.name = name; } public void consume() { string item; while (true) { lock (lockObject) { if (queue.Count == 0) { Monitor.Wait(lockObject); continue; } item = queue.Dequeue(); Console.WriteLine(" {0} Consuming {1}", name, item); } } } } ``` The output is: ``` Producing item1 c2 Consuming item1 Producing item2 c2 Consuming item2 Producing item3 c2 Consuming item3 Producing item4 c2 Consuming item4 Producing item5 c2 Consuming item5 Producing item6 c2 Consuming item6 Producing item7 c2 Consuming item7 Producing item8 c2 Consuming item8 Producing item9 c2 Consuming item9 Producing item10 c2 Consuming item10 Producing item11 c2 Consuming item11 Producing item12 c2 Consuming item12 Producing item13 c2 Consuming item13 Producing item14 c2 Consuming item14 Producing item15 c2 Consuming item15 ```