unity System.Diagnostics.Process类来获取Unity程序的内存使用情况，一直返回0

如果你使用 System.Diagnostics.Process 类来获取 Unity 程序的内存使用情况，一直返回 0 的话，可能是因为 Unity 程序是以 Mono 运行时的方式来启动的。在这种情况下，你需要使用 Mono 提供的方法来获取内存使用情况。你可以使用下面的代码来获取 Unity 程序的内存使用情况：

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

public class MemoryUsage
{
    [DllImport("libc")]
    static extern int getpid();
    
    [DllImport("libproc")]
    static extern int proc_pid_rusage(int pid, int flavor, out RUsageInfo info);

    [StructLayout(LayoutKind.Sequential)]
    struct RUsageInfo
    {
        public long user_time;
        public long system_time;
        public long max_resident_size;
        public long shared_text_size;
        public long unshared_data_size;
        public long unshared_stack_size;
        public long page_reclaims;
        public long page_faults;
        public long swaps;
        public long block_input_ops;
        public long block_output_ops;
        public long messages_sent;
        public long messages_received;
        public long signals_received;
        public long voluntary_context_switches;
        public long involuntary_context_switches;
    }

    public static long GetMemoryUsage()
    {
        int pid = getpid();
        RUsageInfo info;
        int ret = proc_pid_rusage(pid, 0, out info);
        if (ret != 0)
        {
            throw new Exception("Failed to get process resource usage");
        }
        return info.max_resident_size;
    }
}

然后在你的代码中调用 `MemoryUsage.GetMemoryUsage()` 就可以获取 Unity 程序的内存使用情况了。