我一直在测试System.Threading.Parallel和一个线程的性能,我很惊讶地看到并行花费更长的时间完成任务比线程.我确定这是由于我对Parallel的知识有限,我刚刚开始阅读.
我以为我会分享几个片段,如果有人可以指出我的paralle代码运行速度比线程代码慢.还试图运行相同的比较找到素数,发现并行代码完成比线程代码晚.
public class ThreadFactory
{
int workersCount;
private List<Thread> threads = new List<Thread>();
public ThreadFactory(int threadCount,int workCount,Action<int,int,string> action)
{
workersCount = threadCount;
int totalWorkLoad = workCount;
int workLoad = totalWorkLoad / workersCount;
int extraLoad = totalWorkLoad % workersCount;
for (int i = 0; i < workersCount; i++)
{
int min,max;
if (i < (workersCount - 1))
{
min = (i * workLoad);
max = ((i * workLoad) + workLoad - 1);
}
else
{
min = (i * workLoad);
max = (i * workLoad) + (workLoad - 1 + extraLoad);
}
string name = "Working Thread#" + i;
Thread worker = new Thread(() => { action(min,max,name); });
worker.Name = name;
threads.Add(worker);
}
}
public void StartWorking()
{
foreach (Thread thread in threads)
{
thread.Start();
}
foreach (Thread thread in threads)
{
thread.Join();
}
}
}
这是程序：
Stopwatch watch = new Stopwatch();
watch.Start();
int path = 1;
List<int> numbers = new List<int>(Enumerable.Range(0,10000));
if (path == 1)
{
Parallel.ForEach(numbers,x =>
{
Console.WriteLine(x);
Thread.Sleep(1);
});
}
else
{
ThreadFactory workers = new ThreadFactory(10,numbers.Count,(min,text) => {
for (int i = min; i <= max; i++)
{
Console.WriteLine(numbers[i]);
Thread.Sleep(1);
}
});
workers.StartWorking();
}
watch.Stop();
Console.WriteLine(watch.Elapsed.TotalSeconds.ToString());
Console.ReadLine();
更新：
考虑到锁定：我尝试了以下代码段.同样的结果,Parallel似乎完成得比较慢.
path = 1;
cieling = 10000000;
List<int> numbers = new List<int>();
if (path == 1)
{
Parallel.For(0,cieling,x =>
{
lock (numbers)
{
numbers.Add(x);
}
});
}
else
{
ThreadFactory workers = new ThreadFactory(10,text) =>
{
for (int i = min; i <= max; i++)
{
lock (numbers)
{
numbers.Add(i);
}
}
});
workers.StartWorking();
}
更新2：
只是一个快速更新,我的机器有四核处理器.所以Parallel可以有4个内核.
