podman/libpod/runtime_worker.go

package libpod

func (r *Runtime) startWorker() {
	r.workerChannel = make(chan func(), 10)
	go func() {
		for w := range r.workerChannel {
			w()
			r.workerGroup.Done()
		}
	}()
}

func (r *Runtime) queueWork(f func()) {
	r.workerGroup.Add(1)
	go func() {
		r.workerChannel <- f
	}()
}
pod: add exit policies Add the notion of an "exit policy" to a pod. This policy controls the behaviour when the last container of pod exits. Initially, there are two policies: - "continue" : the pod continues running. This is the default policy when creating a pod. - "stop" : stop the pod when the last container exits. This is the default behaviour for `play kube`. In order to implement the deferred stop of a pod, add a worker queue to the libpod runtime. The queue will pick up work items and in this case helps resolve dead locks that would otherwise occur if we attempted to stop a pod during container cleanup. Note that the default restart policy of `play kube` is "Always". Hence, in order to really solve #13464, the YAML files must set a custom restart policy; the tests use "OnFailure". Fixes: #13464 Signed-off-by: Valentin Rothberg <vrothberg@redhat.com> 2022-04-13 14:21:21 +00:00			`package libpod`

			`func (r *Runtime) startWorker() {`
work queue: simplify and use a wait group Simplify the work-queue implementation by using a wait group. Once all queued work items are done, the channel can be closed. The system tests revealed a flake (i.e., #14351) which indicated that the service container does not always get stopped which suggests a race condition when queuing items. Those items are queued in a goroutine to prevent potential dead locks if the queue ever filled up too quickly. The race condition in question is that if a work item queues another, the goroutine for queuing may not be scheduled fast enough and the runtime shuts down; it seems to happen fairly easily on the slow CI machines. The wait group fixes this race and allows for simplifying the code. Also increase the queue's buffer size to 10 to make things slightly faster. [NO NEW TESTS NEEDED] as we are fixing a flake. Fixes: #14351 Signed-off-by: Valentin Rothberg <vrothberg@redhat.com> 2022-05-25 08:08:17 +00:00			`r.workerChannel = make(chan func(), 10)`
pod: add exit policies Add the notion of an "exit policy" to a pod. This policy controls the behaviour when the last container of pod exits. Initially, there are two policies: - "continue" : the pod continues running. This is the default policy when creating a pod. - "stop" : stop the pod when the last container exits. This is the default behaviour for `play kube`. In order to implement the deferred stop of a pod, add a worker queue to the libpod runtime. The queue will pick up work items and in this case helps resolve dead locks that would otherwise occur if we attempted to stop a pod during container cleanup. Note that the default restart policy of `play kube` is "Always". Hence, in order to really solve #13464, the YAML files must set a custom restart policy; the tests use "OnFailure". Fixes: #13464 Signed-off-by: Valentin Rothberg <vrothberg@redhat.com> 2022-04-13 14:21:21 +00:00			`go func() {`
work queue: simplify and use a wait group Simplify the work-queue implementation by using a wait group. Once all queued work items are done, the channel can be closed. The system tests revealed a flake (i.e., #14351) which indicated that the service container does not always get stopped which suggests a race condition when queuing items. Those items are queued in a goroutine to prevent potential dead locks if the queue ever filled up too quickly. The race condition in question is that if a work item queues another, the goroutine for queuing may not be scheduled fast enough and the runtime shuts down; it seems to happen fairly easily on the slow CI machines. The wait group fixes this race and allows for simplifying the code. Also increase the queue's buffer size to 10 to make things slightly faster. [NO NEW TESTS NEEDED] as we are fixing a flake. Fixes: #14351 Signed-off-by: Valentin Rothberg <vrothberg@redhat.com> 2022-05-25 08:08:17 +00:00			`for w := range r.workerChannel {`
			`w()`
			`r.workerGroup.Done()`
pod: add exit policies Add the notion of an "exit policy" to a pod. This policy controls the behaviour when the last container of pod exits. Initially, there are two policies: - "continue" : the pod continues running. This is the default policy when creating a pod. - "stop" : stop the pod when the last container exits. This is the default behaviour for `play kube`. In order to implement the deferred stop of a pod, add a worker queue to the libpod runtime. The queue will pick up work items and in this case helps resolve dead locks that would otherwise occur if we attempted to stop a pod during container cleanup. Note that the default restart policy of `play kube` is "Always". Hence, in order to really solve #13464, the YAML files must set a custom restart policy; the tests use "OnFailure". Fixes: #13464 Signed-off-by: Valentin Rothberg <vrothberg@redhat.com> 2022-04-13 14:21:21 +00:00			`}`
			`}()`
			`}`

			`func (r *Runtime) queueWork(f func()) {`
work queue: simplify and use a wait group Simplify the work-queue implementation by using a wait group. Once all queued work items are done, the channel can be closed. The system tests revealed a flake (i.e., #14351) which indicated that the service container does not always get stopped which suggests a race condition when queuing items. Those items are queued in a goroutine to prevent potential dead locks if the queue ever filled up too quickly. The race condition in question is that if a work item queues another, the goroutine for queuing may not be scheduled fast enough and the runtime shuts down; it seems to happen fairly easily on the slow CI machines. The wait group fixes this race and allows for simplifying the code. Also increase the queue's buffer size to 10 to make things slightly faster. [NO NEW TESTS NEEDED] as we are fixing a flake. Fixes: #14351 Signed-off-by: Valentin Rothberg <vrothberg@redhat.com> 2022-05-25 08:08:17 +00:00			`r.workerGroup.Add(1)`
pod: add exit policies Add the notion of an "exit policy" to a pod. This policy controls the behaviour when the last container of pod exits. Initially, there are two policies: - "continue" : the pod continues running. This is the default policy when creating a pod. - "stop" : stop the pod when the last container exits. This is the default behaviour for `play kube`. In order to implement the deferred stop of a pod, add a worker queue to the libpod runtime. The queue will pick up work items and in this case helps resolve dead locks that would otherwise occur if we attempted to stop a pod during container cleanup. Note that the default restart policy of `play kube` is "Always". Hence, in order to really solve #13464, the YAML files must set a custom restart policy; the tests use "OnFailure". Fixes: #13464 Signed-off-by: Valentin Rothberg <vrothberg@redhat.com> 2022-04-13 14:21:21 +00:00			`go func() {`
			`r.workerChannel <- f`
			`}()`
			`}`