[C#]透過PerformanceCounter取得特定Process的CPU使用率

	var instances = category.GetInstanceNames();
	foreach (var instance in instances)
	{

		using (var counter = new PerformanceCounter(category.CategoryName,
			 "ID Process", instance, true))
		{
			int val = (int)counter.RawValue;
			if (val == pid)
			{
				return instance;
			}
		}
	}
	throw new ArgumentException("Invalid pid!");
}</pre>

	var lastUpdateTime = default(DateTime);

	m_UpdateTimePool.TryGetValue(pid, out lastUpdateTime);

	var interval = DateTime.Now - lastUpdateTime;

	if (interval.TotalSeconds > 1)
	{
		m_CpuUsagePool[pid] = (int)(m_CounterPool[pid].NextValue() / Environment.ProcessorCount);
	}

	return m_CpuUsagePool[pid];
}</pre>

public static class ProcessExtension { #region Private Static Var private static Dictionary<int, PerformanceCounter> _counterPool; private static Dictionary<int, DateTime> _updateTimePool; private static Dictionary<int, int> _cpuUsagePool; #endregion

#region Private Static Property
private static Dictionary<int, PerformanceCounter> m_CounterPool
{
	get
	{
		return _counterPool ?? (_counterPool = new Dictionary<int, PerformanceCounter>());
	}
}

private static Dictionary<int, DateTime> m_UpdateTimePool
{
	get
	{
		return _updateTimePool ?? (_updateTimePool = new Dictionary<int, DateTime>());
	}
}

private static Dictionary<int, int> m_CpuUsagePool
{
	get
	{
		return _cpuUsagePool ?? (_cpuUsagePool = new Dictionary<int, int>());
	}
}
#endregion


#region Private Static Method
private static string GetProcessInstanceName(int pid)
{
	var category = new PerformanceCounterCategory("Process");

	var instances = category.GetInstanceNames();
	foreach (var instance in instances)
	{

		using (var counter = new PerformanceCounter(category.CategoryName,
			 "ID Process", instance, true))
		{
			int val = (int)counter.RawValue;
			if (val == pid)
			{
				return instance;
			}
		}
	}
	throw new ArgumentException("Invalid pid!");
}

private static int GetCpuUsage(int pid)
{
	if (!m_CounterPool.ContainsKey(pid))
	{
		m_CounterPool.Add(pid, new PerformanceCounter("Process", "% Processor Time", GetProcessInstanceName(pid)));
	}

	var lastUpdateTime = default(DateTime);

	m_UpdateTimePool.TryGetValue(pid, out lastUpdateTime);

	var interval = DateTime.Now - lastUpdateTime;

	if (interval.TotalSeconds > 1)
	{
		m_CpuUsagePool[pid] = (int)(m_CounterPool[pid].NextValue() / Environment.ProcessorCount);
	}

	return m_CpuUsagePool[pid];
}
#endregion


#region Public Static Method
public static string GetInstanceName(this Process process)
{
	return GetProcessInstanceName(process.Id);
}

public static int GetCpuUsage(this Process process)
{
	return GetCpuUsage(process.Id);
}
#endregion

}

namespace WindowsFormsApplication24 { public partial class Form1 : Form { public Form1() { InitializeComponent(); }

	private void Form1_Load(object sender, EventArgs e)
	{
		timer1.Interval = 1000;
		lbxProcess.DisplayMember = "ProcessName";
		lbxProcess.DataSource = Process.GetProcesses();
	}

	private void lbxProcess_SelectedIndexChanged(object sender, EventArgs e)
	{
		var selectedProcess = lbxProcess.SelectedItem as Process;
		if (selectedProcess == null)
			return;

		timer1.Enabled = false;
		tbxInstanceName.Text = selectedProcess.GetInstanceName();
		tbxCPU.Text = selectedProcess.GetCpuUsage().ToString();
		timer1.Enabled = true;
	}

	private void timer1_Tick(object sender, EventArgs e)
	{
		var selectedProcess = lbxProcess.SelectedItem as Process;
		if (selectedProcess == null)
			return;

		tbxCPU.Text = selectedProcess.GetCpuUsage().ToString();
	}
}

}

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