mirror of
https://github.com/modernuo/ModernUO
synced 2026-08-11 22:23:06 -04:00
## Problem On headless Linux deployments (systemd service, Docker without a TTY, `nohup`), the ModernUO process pegs a full CPU core even when idle. It does not reproduce on Windows because that runs with an interactive console. ## Root cause `ConsoleInputHandler` runs a background thread (named "Console Input Handler") that loops on `Console.ReadLine()`. When stdin is **not** an interactive terminal, `Console.ReadLine()` returns `null` at end-of-stream **immediately** on every call, so the loop `continue`s in a tight spin — one core at 100%. Reproduced in a container running the actual distribution: the "Console Input Handler" thread sat at ~90% CPU on a headless boot; with a blocking stdin it dropped to idle. ## Fix 1. **Detect headless once at startup:** `Core.Headless = Console.IsInputRedirected`. 2. **Extract a testable `ConsoleInputPump`** that owns the input stream: per line read, it *atomically* (under one lock) either delivers the line to a waiting prompt or dispatches a console command, and it **ends on EOF instead of spinning**. Cleanup runs unconditionally in a `finally`, so a pending prompt is always released (never hangs). Replaces the old `async void` loop and the fragile `_expectUserInput` / two-`AutoResetEvent` / `_input` handshake. 3. **`ConsoleInputHandler` becomes a thin headless-aware facade** over the pump. Headless: the reader thread never starts (`Console input disabled (headless: stdin is not a TTY).`), and `ReadLine()` throws a fatal `HeadlessConsoleInputException`. 4. **Data-gating and first-boot prompts** (deserialization "delete bad types? y/n", save-conflict, config/expansion setup) now route through `ConsoleInputHandler.ReadLine()`, so a headless server crashes fatal with a clear message instead of reading `null` (previously an NRE or a silent wrong branch). Design decision (model b): headless servers are expected to be supplied with configuration/save data (including the owner account); interactive prompts when headless are fatal by design. ## Testing - New `ConsoleInputPumpTests` (5 tests): EOF ends the loop without spinning; command dispatch; a pending prompt receives the next line; EOF while a prompt is pending completes it with `null` (no hang); a throwing command lookup does not hang a pending prompt. The tests synchronize on real pump state (no `Thread.Sleep`), so they are deterministic on slow CI. - Full `Server.Tests`: no new failures introduced. ## End-to-end verification (Docker, real distribution) | | Console Input Handler thread | Container CPU | |---|---|---| | Before fix (headless boot) | ~90% | ~199% (2 cores) | | After fix (headless boot) | **not started** | **~11%** | After the fix, a headless boot logs `Console input disabled (headless: stdin is not a TTY).`, loads the world normally, and idles instead of spinning.
123 lines
3.4 KiB
C#
123 lines
3.4 KiB
C#
using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Net;
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namespace Server;
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public static class ServerConfigurationPrompts
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{
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internal static List<string> GetDataDirectories()
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{
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Console.WriteLine("Please enter the absolute path to your ClassicUO or Ultima Online data:");
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var directories = new List<string>();
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do
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{
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Console.Write("{0}> ", directories.Count > 0 ? "[enter to finish]" : " ");
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var directory = ConsoleInputHandler.ReadLine();
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if (string.IsNullOrWhiteSpace(directory))
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{
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break;
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}
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if (Directory.Exists(directory))
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{
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directories.Add(directory);
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Console.Write("Added ");
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Utility.PushColor(ConsoleColor.Green);
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Console.Write(directory);
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Utility.PopColor();
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Console.WriteLine(".");
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}
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else
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{
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Utility.PushColor(ConsoleColor.Red);
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Console.Write(directory);
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Utility.PopColor();
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Console.WriteLine(" does not exist.");
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}
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} while (true);
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return directories;
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}
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internal static List<IPEndPoint> GetListeners()
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{
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Console.WriteLine("Please enter the IP and ports to listen:");
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Console.WriteLine(" - Only enter IP addresses directly bound to this machine");
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Console.WriteLine(" - To listen to all IP addresses enter 0.0.0.0");
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var ips = new List<IPEndPoint>();
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do
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{
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// IP:Port?
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Console.Write("[{0}]> ", ips.Count > 0 ? "enter to finish" : "0.0.0.0:2593");
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var ipStr = ConsoleInputHandler.ReadLine();
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IPEndPoint ip;
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if (string.IsNullOrWhiteSpace(ipStr))
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{
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if (ips.Count > 0)
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{
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break;
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}
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ip = new IPEndPoint(IPAddress.Any, 2593);
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}
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else
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{
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if (!ipStr.ContainsOrdinal(':'))
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{
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ipStr += ":2593";
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}
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if (!IPEndPoint.TryParse(ipStr, out ip))
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{
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Utility.PushColor(ConsoleColor.Red);
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Console.Write(ipStr);
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Utility.PopColor();
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Console.WriteLine(" is not a valid IP or port.");
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continue;
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}
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}
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ips.Add(ip);
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Console.Write("Added ");
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Utility.PushColor(ConsoleColor.Green);
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Console.Write(ip);
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Utility.PopColor();
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Console.WriteLine(".");
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} while (true);
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return ips;
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}
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internal static string GetServerName()
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{
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Console.WriteLine("Please enter the name of your shard:");
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string serverName;
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do
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{
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Console.Write("[ModernUO]> ");
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serverName = ConsoleInputHandler.ReadLine();
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if (string.IsNullOrWhiteSpace(serverName))
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{
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serverName = "ModernUO";
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}
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break;
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} while (true);
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Console.Write("Server name set to ");
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Utility.PushColor(ConsoleColor.Green);
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Console.Write(serverName);
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Utility.PopColor();
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Console.WriteLine(".");
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return serverName;
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}
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}
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