Consider using kqueue in hypervisor socket implementation
Nobody has claimed this yet.
Assessment
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Newbie friendliness
- 45/100
- Issue type
- Bug
- Clarity
- Mostly clear
- Activity status
- Stale
- Tech stack
- c
- Domain
- networking, operating-systems
Research direction
Start with src/lib/pci_virtio_sock.c around the select and accepted file-descriptor handling, then compare the event-management approach in mevent.c. Determine whether kqueue or poll is appropriate, preserve AF_VSOCK connection processing, and verify that descriptors above FD_SETSIZE can be handled under the reported connection load.
Written by the indexing model from the issue text.
Description
The core of hyperkit uses kqueue via mevent.c but pci_virtio_sock.c uses plain old select.
If hyperkit is used together with vpnkit in Docker for Mac and large numbers (> 1024) of connections are port forwarded then hyperkit becomes unable to process any more AF_VSOCK connections due to the accepted file descriptor being greater than FD_SETSIZE, see for example https://github.com/moby/hyperkit/blob/3ace9850121a2ef270e0309a3ff6c2f991357842/src/lib/pci_virtio_sock.c#L1364
This manifests as errors under load, for example
$ docker ps
Error response from daemon: Bad response from Docker engine
from https://github.com/docker/for-mac/issues/2841
This scalability limit could be removed by switching from select to kqueue (or poll) in pci_virtio_sock.c.
- Dominant language
- C
- Stars
- 3.7k
- Forks
- 336
- PR merge metrics
- No merged PRs in 30d
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
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