Highly Performant & Scalable Ultima Online Server Emulator
https://www.modernuo.com
c-sharpcsharpcsharp-coredotnetdotnet-coreemulatorgplgplv3mmommo-enginemmorpgmmorpg-serveronlinerpgrunuoserverservuoultimaultima-onlineuo
1a9cec1dbb
## Summary `AdvancedSearchThreadWorker.Execute` signals `_stopEvent` **before** clearing `_pause` and **before** reading the exit condition. `Sleep()` unblocks the instant that signal fires, so the owning thread can begin the next cycle while the worker is still finishing the previous one — and the worker's two trailing operations then land on the new cycle's state. `SerializationThreadWorker` already orders the same handshake correctly and documents why (`Projects/Server/Serialization/SerializationThreadWorker.cs`): ```csharp // The owning thread may start another pause cycle the moment _stopEvent is set // (Exit does exactly that). Clear _pause and sample the exit condition before // signaling, or the new cycle's pause request is clobbered / its Sleep orphaned. var exiting = Core.Closing || worker._exit; Volatile.Write(ref worker._pause, false); worker._stopEvent.Set(); ``` This applies the same ordering to the search worker. Three lines; no behavior change on the happy path. ## The two failures **Reuse hang.** The next cycle's `Wake`/`Push`/`Sleep` writes `_pause = true`, then the worker's stale `_pause = false` lands on top of it. The inner loop never observes `pauseRequested`, its queue is already empty, and it spins on `Thread.Yield()` forever — so the owning thread's next `Sleep()` waits on a `_stopEvent` that is never set again. A single search wakes each worker exactly once, so this only surfaces once `_threadWorkers` is reused by a later search. **Orphaned `Exit()`.** `Exit()` sets `_exit`, `Wake()`s, then `Sleep()`s — the moment the drain's `Sleep()` returns. Reading `_exit` *after* the signal, the worker can observe that fresh `_exit`, return without ever consuming the `Wake`, and leave `Exit()`'s `Sleep()` waiting on a signal nobody will send. The `_thread.IsAlive` guard doesn't close this: the thread passes the check and returns immediately after. ## Verification Verified with two throwaway timing tests — 25k reuse cycles and 2k drain-then-`Exit` cycles, each under a bounded wait: | ordering | result | |---|---| | previous | `Failed: 2, Passed: 3` — both reproduce, cleanly at the 20s bound | | this PR | 3 consecutive runs, 5/5, ~0.6s | **Those tests are deliberately not included.** Their reproduction threshold is a property of one machine's scheduler — at 2k and 200 cycles the buggy build passed — so as permanent tests they'd cost ~560ms and 2000 thread creations on every suite run for a guarantee that may not hold on a CI runner. The ordering is protected the same way `SerializationThreadWorker`'s is: by the comment at the call site. `UOContent.Tests`: **597/597**. |
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ModernUO 
Ultima Online Server Emulator for the modern era!
Requirements
Supported Operating Systems
Required Frameworks
All Operating Systems
Windows
Development
Supported IDEs
Getting Started
- Install prerequisite requirements
- Clone this repository (or download the latest):
git clone https://github.com/modernuo/ModernUO.git
- Open
ModernUO.slnto start developing
Building/Publishing
Interactive Mode (Recommended for new users)
Run ./publish.cmd (Windows) or ./publish.sh (Linux/macOS) with no arguments to launch the guided build tool. It will:
- Check prerequisites (.NET SDK, native libraries)
- Walk you through configuration and platform selection
- Build and publish the server to the
Distributiondirectory - Show deployment instructions for cross-compiled builds
Command Line
./publish.cmd [release|debug] [os] [arch]
os- Supported operating systemsarchx64- Intel/AMD 64-bitarm64- ARM 64-bit
Linux Prerequisites
Fedora, CentOS, RHEL, AlmaLinux, Rocky, etc
dnf upgrade --refresh -y
# RHEL-family distributions (CentOS Stream, AlmaLinux, Rocky, RHEL) need CRB and EPEL enabled.
# Fedora skips this block.
dnf install -y dnf-plugins-core
dnf config-manager --set-enabled crb
dnf install -y epel-release
# Prerequisites
dnf install -y findutils libicu libdeflate-devel zstd libargon2-devel liburing-devel
Ubuntu, Debian, etc
apt-get update -y
apt-get install -y libicu-dev libdeflate-dev zstd libargon2-dev liburing-dev
OSX Requirements
brew install icu4c libdeflate zstd argon2
Running the Server
- Follow the publish instructions
- The
Distributiondirectory is portable — copy it to your production server for deployment - Run
ModernUO.exeordotnet ModernUO.dllfrom theDistributiondirectory - On first run, the server will prompt you to configure game data file locations
Troubleshooting / FAQ
- See FAQ
Want to sponsor?
Thank you for supporting us! You can find out how by visiting the sponsors page.
Collaborators
Thanks
- RunUO Team & Community
- Voxpire, the ServUO Team & Community
- Karasho, Jaedan and the ClassicUO Community
Development Tools & Plugins provided with ♥ by
Code Signing Policy
Free code signing provided by SignPath.io, certificate by SignPath Foundation.
This program will not transfer any information to other networked systems unless specifically requested by the user or the person installing or operating it
Teams & Roles
Approvers & Committers: Development Team