42fe9810a4
Flush() allocated two fresh arrays sized to the live entry count and copied the whole dictionary into them, on the game loop, every 60s. UInt128 is 16 bytes, so past ~5,300 entries that first array is an LOH allocation once a minute, forever -- and a large shard accumulates thousands of addresses easily. The file write was already off-loop; the walk was not. Buffers are now static, grown geometrically and never shrunk, so a steady shard stops allocating here entirely. The writer owns them until it posts completion back through Core.LoopContext, so a flush landing mid-write waits rather than overwriting them (CLAUDE.md rule #10 -- _writing and _dirty stay loop state and the writer never touches them itself). Default flush interval goes to an hour. The data has a 90-day TTL, so a minute was never buying anything, and the interval now only bounds what a crash loses: - Clean shutdown writes synchronously via EventSink.Shutdown. Handing off would reach no disk; nothing schedules after that point. - HandleClosed skips InvokeShutdown when the server crashed, so the crash path subscribes separately, following PasswordWorker's precedent. The handler runs on whichever thread faulted -- the loop thread for anything out of RunEventLoop, but not necessarily -- and the dictionaries are loop state, so it only writes when it is actually on the loop. Also fixes a pre-existing hole: _dirty was cleared before the write, so a failed write dropped the entries until the next RecordLogin happened to set it again, despite the comment promising a retry. Write now reports success and _dirty is restored when nothing reached disk. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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|---|---|---|
| .config | ||
| .github | ||
| branding | ||
| dev-docs | ||
| Distribution/Data | ||
| Projects | ||
| tools | ||
| .cursorrules | ||
| .editorconfig | ||
| .gitattributes | ||
| .gitignore | ||
| AGENTS.md | ||
| azure-pipelines.yml | ||
| CLAUDE.md | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| Directory.Build.props | ||
| FAQ.md | ||
| GEMINI.md | ||
| global.json | ||
| LICENSE | ||
| ModernUO.slnx | ||
| publish.cmd | ||
| publish.ps1 | ||
| publish.sh | ||
| README.md | ||
| rider-settings.zip | ||
| Rules.ruleset | ||
| SPONSORS.md | ||
| stylecop.json | ||
| THIRD-PARTY-NOTICES | ||
| version.json | ||
ModernUO 
Ultima Online Server Emulator for the modern era!
Requirements
Supported Operating Systems
Required Frameworks
All Operating Systems
Windows
Hardware
| Use | vCPU | RAM | Storage |
|---|---|---|---|
| Development / test | 2 dedicated | 2 GB | SSD |
| Small live shard (< 50 concurrent) | 4 dedicated | 4 GB | NVMe |
| Medium (50–200) | 4–8 | 8 GB | NVMe |
| Large (200+) | 8+, high clock | 16 GB+ | NVMe |
Game logic is single-threaded, so single-core clock speed matters more than core count, and dedicated vCPU matters more than either — burstable or shared plans throttle once credits run out, which is the most common cause of unexplained lag spikes. Save size drives RAM more than player count does.
See dev-docs/server-requirements.md for the reasoning and tuning options.
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 libargon2 tzdata
Ubuntu, Debian, etc
apt-get update -y
# The ICU runtime package carries the ABI version in its name (libicu74, libicu76, …) and has no
# stable alias, so match it by pattern rather than pinning a release-specific name.
apt-get install -y '^libicu[0-9]+$' libdeflate0 libargon2-1 tzdata
Only the runtime libraries are needed — the -dev/-devel packages are not. Run
./build-tool --check-prereqs to check the current machine and print the exact packages your
release needs.
zstd is not listed because ZstdNet bundles libzstd for every platform, and liburing is not
listed because IORingGroup issues io_uring syscalls directly.
If the shard's configured time zone is a legacy alias such as US/Eastern, Debian 12 and Ubuntu
24.04 also need tzdata-legacy. See Platform Prerequisites
for what each dependency is for and what breaks without it.
OSX Requirements
brew install icu4c libdeflate 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