How to Set the Maximum Memory a Process can Use at the OS Level

using (Process p = new Process())
{
    p.StartInfo = new ProcessStartInfo("myexe.exe");
    p.Start();
 
    using (PublicDomain.Win32.Job j = PublicDomain.Win32.Job.CreateJobWithMemoryLimits(
        (uint)GlobalConstants.BytesInAMegabyte * 12,
        (uint)GlobalConstants.BytesInAMegabyte * 30,
        p))
    {
        // As long as the Job object j is alive, there
        // will be a memory limit of 30 Mb on the Process p
    }
 
    // HERE the process is still running but there should no longer be any limits on it
}

public void SetHardLimit(string ProcessName,uint ProcessMinSize, uint ProcessMaxSize)
{
    Process[] processlist = Process.GetProcessesByName(ProcessName);
 
    Win32.Job job = new Win32.Job(StringUtilities.RandomString(10, true));
    job.SetLimitWorkingSetSize(ProcessMinSize, ProcessMaxSize);
    foreach (Process p in processlist)
    {
        try
        {
            job.AssignProcess(p);
        }
        catch
        {
        }
    }
}

public Win32.Job SetHardLimit(string ProcessName,uint ProcessMinSize, uint ProcessMaxSize)
{
    ...
    return job;
}
 
private Win32.Job m_job;
 
public void SetLimits()
{
    RemoveLimits();
    m_job = SetHardLimit("...", 11111, 1111);
}
 
public void RemoveLimits()
{
    if (m_job != null)
    {
        m_job.Dispose();
        m_job = null;
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using PublicDomain;
using System.Diagnostics;
 
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
 
        private Win32.Job m_job;
 
        public static Win32.Job CreateJobWithMemoryLimits(
            uint minWorkingSetSize,
            uint maxWorkingSetSize,
            params Process[] processesToLimit)
        {
            Win32.Job job = new Win32.Job(StringUtilities.RandomString(10, true));
            job.SetLimitWorkingSetSize(minWorkingSetSize, maxWorkingSetSize);
 
            foreach (Process p in processesToLimit)
            {
                try
                {
                    job.AssignProcess(p);
                }
                catch (Exception e)
                {
                    MessageBox.Show(e.ToString());
                }
            }
            return job;
        }
 
        public void RemoveLimits()
        {
            if (m_job != null)
            {
                m_job.Dispose();
                m_job = null;
            }
        }
 
        public void ChangeLimits()
        {
            RemoveLimits();
            Process[] ProcessList = Process.GetProcessesByName("MYPROCESSES");
 
            m_job = CreateJobWithMemoryLimits(
                uint.Parse(textBox1.Text) * 1048576,
                uint.Parse(textBox2.Text) * 1048576,
                ProcessList);
        }
 
        private void BT1Set_Click(object sender, EventArgs e)
        {
            ChangeLimits();
        }
 
        private void BT3Release_Click(object sender, EventArgs e)
        {
            RemoveLimits();
        }
 

    }
}