MemEater

MemEater.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Threading;

namespace MemEater
{
	static class MainClass
	{
		private static readonly Random Random = new Random();
		private const Int64 Kilobyte = 1024;
		private const Int64 Megabyte = Kilobyte * 1024;
		private const Int64 Gigabyte = Megabyte * 1024;

		private static string StrSize(Int64 bytes)
		{
			if (bytes >= Gigabyte) {
				return $"{bytes /(float) Gigabyte: 0.##} Gbytes ({bytes} bytes)";
			}
			if (bytes >= Megabyte) {
				return $"{bytes / (float)Megabyte: 0.##} Mbytes ({bytes} bytes)";
			}
			if (bytes >= Kilobyte) {
				return $"{bytes / (float)Kilobyte: 0.##} Kbytes ({bytes} bytes)";
			}
			return $"{bytes} bytes";
		}
		
		public static void Main(string[] args)
		{
			var step = Megabyte;
			if (args.Length >= 1) {
				step = int.Parse (args [0]);
			}
			
			var numThreads = 1;
			if (args.Length >= 2) {
				numThreads = int.Parse (args [1]);
			}
			
			Console.WriteLine($"Process ID: {Process.GetCurrentProcess().Id}");
			Console.WriteLine($"Increment size: {step } bytes");
			Console.WriteLine($"Creating {numThreads} threads");
			for (var i = 0; i < numThreads; i++)
			{
				var t = new Thread(Work) {Name = $"Eater#{i}"};
				t.Start(step);
			}
			
			while (true)
			{
				Thread.Sleep(5000);
				{
					Process currentProc = Process.GetCurrentProcess();
					Console.WriteLine ($"Process size: {StrSize(currentProc.PrivateMemorySize64)}");
					Console.WriteLine ();
				}
			}
		}
		
		private class Node {
			public byte[] data;
			public Node prev;
		}

		public static void Work (object param)
		{
			Console.WriteLine($"Thread {Thread.CurrentThread.Name} started");
			
			var step = (Int64)param;

			var start = DateTime.Now;
			
			Node prev = null;

			while(true) {
				var data = new byte[step + (long)(Random.NextDouble() * step)];
				var node = new Node();
				node.data = data;
				node.prev = prev;
				prev = node;

				for (var j = 0; j < data.Length; j += 10) {
					data [j] = 10;
				}
			}
		}
	}
}

nikita@nikita-OptiPlex-9020:~/MemEater$ sudo sysctl -w vm.max_map_count=8000
[sudo] password for nikita: 
vm.max_map_count = 25000
nikita@nikita-OptiPlex-9020:~/MemEater$ mono MemEater.exe 128 120 2>&1 | tee log.txt
Process ID: 4529
Increment size: 128 bytes
Creating 120 threads
Thread Eater#1 started
Thread Eater#0 started
Thread Eater#2 started
Thread Eater#3 started
Thread Eater#4 started
Thread Eater#5 started
Thread Eater#6 started
Thread Eater#7 started
Thread Eater#8 started
Thread Eater#9 started
... A lot of output ...
Thread 2 (Thread 0x7f0df0fff700 (LWP 4531)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00000000005fdcdb in ?? ()
#2  0x00007f0df22756ba in start_thread (arg=0x7f0df0fff700) at pthread_create.c:333
#3  0x00007f0df1fab3dd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7f0df2da9780 (LWP 4529)):
#0  0x00007f0df1ed9826 in __GI___sigsuspend (set=0x956e00) at ../sysdeps/unix/sysv/linux/sigsuspend.c:30
#1  0x00000000005cc5e4 in ?? ()
#2  0x00000000005cc73f in ?? ()
#3  <signal handler called>
#4  __clock_nanosleep (clock_id=<optimized out>, flags=1, req=0x7ffd03521260, rem=0x0) at ../sysdeps/unix/sysv/linux/clock_nanosleep.c:48
#5  0x0000000000617160 in ?? ()
#6  0x000000000058743a in ?? ()
#7  0x0000000041346bb2 in ?? ()
#8  0x00007f0df2cfe230 in ?? ()
#9  0x00007f0df2cfe230 in ?? ()
#10 0x0000000000000078 in ?? ()
#11 0x0000000000000078 in ?? ()
#12 0x0000000000000080 in ?? ()
#13 0x000000000219c080 in ?? ()
#14 0x0000000000000000 in ?? ()

=================================================================
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries 
used by your application.
=================================================================

From other window:

nikita@nikita-OptiPlex-9020:~/MemEater$ while true ; do pmap 4529 | wc -l; sleep 3 ; done            
7108
8003
8003
8003
8003
8004
8004
8004
8004
...