48b1b01e69
The `disconnect.stop_on_client_after` feature is implemented as a loop on the client that's intended to wait on the shortest timeout of all the allocations on the node and then check whether the interval since the last heartbeat has been longer than the timeout. It uses a buffered channel of allocations written and read from the same goroutine to push "stops" from the timeout expiring to the next pass through the loop. Unfortunately if there are multiple allocations that need to be stopped in the same timeout event, or even if a previous event has not yet been dequeued, then sending on the channel will block and the entire goroutine deadlocks itself. While fixing this, I also discovered that the `stop_on_client_after` and heartbeat loops can synchronize in a pathological way that extends the `stop_on_client_after` window. If a heartbeat fails close to the beginning of the shortest `stop_on_client_after` window, the loop will end up waiting until almost 2x the intended wait period. While fixing both of those issues, I discovered that the existing tests had a bug such that we were asserting that an allocrunner was being destroyed when it had already exited. This commit includes the following: * Rework the watch loop so that we handle the stops in the same case as the timer expiration, rather than using a channel in the method scope. * Remove the alloc intervals map field from the struct and keep it in the method scope, in order to discourage writing racy tests that read its value. * Reset the timer whenever we receive a heartbeat, which forces the two intervals to synchronize correctly. * Minor refactoring of the disconnect timeout lookup to improve brevity. Fixes: https://github.com/hashicorp/nomad/issues/24679 Ref: https://hashicorp.atlassian.net/browse/NMD-407
Nomad
Nomad is a simple and flexible workload orchestrator to deploy and manage containers (docker, podman), non-containerized applications (executable, Java), and virtual machines (qemu) across on-prem and clouds at scale.
Nomad is supported on Linux, Windows, and macOS. A commercial version of Nomad, Nomad Enterprise, is also available.
- Website: https://developer.hashicorp.com/nomad
- Tutorials: HashiCorp Developer
- Forum: Discuss
Nomad provides several key features:
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Deploy Containers and Legacy Applications: Nomad’s flexibility as an orchestrator enables an organization to run containers, legacy, and batch applications together on the same infrastructure. Nomad brings core orchestration benefits to legacy applications without needing to containerize via pluggable task drivers.
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Simple & Reliable: Nomad runs as a single binary and is entirely self contained - combining resource management and scheduling into a single system. Nomad does not require any external services for storage or coordination. Nomad automatically handles application, node, and driver failures. Nomad is distributed and resilient, using leader election and state replication to provide high availability in the event of failures.
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Device Plugins & GPU Support: Nomad offers built-in support for GPU workloads such as machine learning (ML) and artificial intelligence (AI). Nomad uses device plugins to automatically detect and utilize resources from hardware devices such as GPU, FPGAs, and TPUs.
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Federation for Multi-Region, Multi-Cloud: Nomad was designed to support infrastructure at a global scale. Nomad supports federation out-of-the-box and can deploy applications across multiple regions and clouds.
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Proven Scalability: Nomad is optimistically concurrent, which increases throughput and reduces latency for workloads. Nomad has been proven to scale to clusters of 10K+ nodes in real-world production environments.
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HashiCorp Ecosystem: Nomad integrates seamlessly with Terraform, Consul, Vault for provisioning, service discovery, and secrets management.
Quick Start
Testing
See Developer: Getting Started for instructions on setting up a local Nomad cluster for non-production use.
Optionally, find Terraform manifests for bringing up a development Nomad cluster on a public cloud in the terraform directory.
Production
See Developer: Nomad Reference Architecture for recommended practices and a reference architecture for production deployments.
Documentation
Full, comprehensive documentation is available on the Nomad website: https://developer.hashicorp.com/nomad/docs
Guides are available on HashiCorp Developer.
Roadmap
A timeline of major features expected for the next release or two can be found in the Public Roadmap.
This roadmap is a best guess at any given point, and both release dates and projects in each release are subject to change. Do not take any of these items as commitments, especially ones later than one major release away.
Contributing
See the contributing directory for more developer documentation.