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On Thu, Jun 28, 2018 at 03:48:26AM -0700, Marco Vedovati wrote [1]:
> The root cause is a deadlock between two channel writes made by two
> different goroutines:
>
> 1. `resizeTty() : go func(){} : sendUpdate()` is sending a resize
> message thru `resize` right at the beginning, but the channel is
> never read if some startup error occurs.
>
> 2. Upon program termination, `startAttachCtr() : defer func(){} ` is
> telling the goroutine in "1." to stop via the `resizeTerminate`
> channel. But that guy is still waiting for the write to `resize`
> to complete so the the termination message is never read.
>
> I think the go deadlock detection does not kick in because not all
> goroutines are seen as asleep. E.g. `os/signal Notify()` is enough
> to have the deadlock not detected.
333ab8c2 (Fix podman hangs when detecting startup error in container
attached mode, 2018-06-27, #1010) addressed this with a deferred
drain. This commit adjusts that approach to use a single select to
cover "have we been canceled?", "has there been a resize signal?", and
(when we have one) "can we write the most recent resize event to the
resize channel?".
A side benefit to this approach is that if we have a slow resize
consumer and several resize signals, the resizeTty function will keep
updating its local resizeEvent. Once the resize channel is able to
accept, only the most-recent event will be written. Previously we'd
have written one resize event for every received signal, even if the
resize consumer was falling behind.
[1]: https://github.com/projectatomic/libpod/pull/1010#issuecomment-400994436
Signed-off-by: W. Trevor King <wking@tremily.us>
Closes: #1018
Approved by: rhatdan
podman - Simple debugging tool for pods and images
podman is a daemonless container runtime for managing containers, pods, and container images. It is intended as a counterpart to CRI-O, to provide low-level debugging not available through the CRI interface used by Kubernetes. It can also act as a container runtime independent of CRI-O, creating and managing its own set of containers.
Use cases
- Create containers
- Start, stop, signal, attach to, and inspect existing containers
- Run new commands in existing containers
- Push and pull images
- List and inspect existing images
- Create new images by committing changes within a container
- Create pods
- Start, stop, signal, and inspect existing pods
- Populate pods with containers