Ethan
cda460f5df
## Problem Scaletest follow-up storms showed that the chat stream path was doing a same-replica DB reread for every durable message it had already delivered locally. In a 600-chat / 10-turn run, `/stream`-attributed `GetChatMessagesByChatID` calls reached about 14.2k across 5,400 follow-up turns — roughly **2.63 rereads per turn**. The primary coderd replicas saturated their DB pools at 60/60 open connections during the storm window. The root cause: when pubsub was active, `Subscribe()` suppressed local durable `message` events and relied entirely on pubsub notify → `GetChatMessagesByChatID` for catch-up. Same-replica subscribers paid the full DB round-trip even though the persisting process was on the same replica. ## Solution Add a bounded per-chat **durable message cache** to `chatStreamState` so that same-replica subscribers can catch up from memory instead of the database. ### How it works 1. `publishMessage()` caches the SDK event in `chatStreamState` before local fanout and pubsub notify. 2. `publishEditedMessage()` replaces the cache with only the edited message, then publishes `FullRefresh`. 3. `Subscribe()` handles ordinary `AfterMessageID` notifies by first consulting the per-chat durable cache and only falling back to `GetChatMessagesByChatID` on cache miss. 4. `FullRefresh` always forces a DB reread (cache is bypassed). ### Safety properties - If the cache misses (e.g. message expired or remote replica), the DB catch-up still runs — no silent message loss. - `FullRefresh` (edits) always rereads from the database. - Remote replicas still use the pubsub + DB path unchanged. - The cache is bounded (`maxDurableMessageCacheSize = 256`) and scoped per chat — no unbounded memory growth. ## Impact This change removes the entire same-replica portion of the stream rereads. Based on the 600-chat follow-up run, the upper bound on saved work is the same-replica share of about 14.2k `GetChatMessagesByChatID` rereads, with the observed total stream reread rate at about 2.63 rereads per follow-up turn.
Coder enables organizations to set up development environments in their public or private cloud infrastructure. Cloud development environments are defined with Terraform, connected through a secure high-speed Wireguard® tunnel, and automatically shut down when not used to save on costs. Coder gives engineering teams the flexibility to use the cloud for workloads most beneficial to them.
- Define cloud development environments in Terraform
- EC2 VMs, Kubernetes Pods, Docker Containers, etc.
- Automatically shutdown idle resources to save on costs
- Onboard developers in seconds instead of days
Quickstart
The most convenient way to try Coder is to install it on your local machine and experiment with provisioning cloud development environments using Docker (works on Linux, macOS, and Windows).
# First, install Coder
curl -L https://coder.com/install.sh | sh
# Start the Coder server (caches data in ~/.cache/coder)
coder server
# Navigate to http://localhost:3000 to create your initial user,
# create a Docker template and provision a workspace
Install
The easiest way to install Coder is to use our
install script for Linux
and macOS. For Windows, use the latest ..._installer.exe file from GitHub
Releases.
curl -L https://coder.com/install.sh | sh
You can run the install script with --dry-run to see the commands that will be used to install without executing them. Run the install script with --help for additional flags.
See install for additional methods.
Once installed, you can start a production deployment with a single command:
# Automatically sets up an external access URL on *.try.coder.app
coder server
# Requires a PostgreSQL instance (version 13 or higher) and external access URL
coder server --postgres-url <url> --access-url <url>
Use coder --help to get a list of flags and environment variables. Use our install guides for a complete walkthrough.
Documentation
Browse our docs here or visit a specific section below:
- Templates: Templates are written in Terraform and describe the infrastructure for workspaces
- Workspaces: Workspaces contain the IDEs, dependencies, and configuration information needed for software development
- IDEs: Connect your existing editor to a workspace
- Administration: Learn how to operate Coder
- Premium: Learn about our paid features built for large teams
Support
Feel free to open an issue if you have questions, run into bugs, or have a feature request.
Join our Discord to provide feedback on in-progress features and chat with the community using Coder!
Integrations
We are always working on new integrations. Please feel free to open an issue and ask for an integration. Contributions are welcome in any official or community repositories.
Official
- VS Code Extension: Open any Coder workspace in VS Code with a single click
- JetBrains Toolbox Plugin: Open any Coder workspace from JetBrains Toolbox with a single click
- JetBrains Gateway Plugin: Open any Coder workspace in JetBrains Gateway with a single click
- Dev Container Builder: Build development environments using
devcontainer.jsonon Docker, Kubernetes, and OpenShift - Coder Registry: Build and extend development environments with common use-cases
- Kubernetes Log Stream: Stream Kubernetes Pod events to the Coder startup logs
- Self-Hosted VS Code Extension Marketplace: A private extension marketplace that works in restricted or airgapped networks integrating with code-server.
- Setup Coder: An action to setup coder CLI in GitHub workflows.
Community
- Provision Coder with Terraform: Provision Coder on Google GKE, Azure AKS, AWS EKS, DigitalOcean DOKS, IBMCloud K8s, OVHCloud K8s, and Scaleway K8s Kapsule with Terraform
- Coder Template GitHub Action: A GitHub Action that updates Coder templates
Contributing
We are always happy to see new contributors to Coder. If you are new to the Coder codebase, we have a guide on how to get started. We'd love to see your contributions!
Hiring
Apply here if you're interested in joining our team.