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Stephan BehnkeandGitHub
a15204553b
## What changed? <!-- Describe what has changed in this PR --> Clear all workflow contexts, found in the cache, that belong to a History Shard that is being closed. ## Why? <!-- Tell your future self why have you made these changes --> Right now, when a History Shard is closed, any non-durable Update that is still in-flight will be "lost", meaning that there is no way to access it, cancel it or complete it anymore. The client that issued the Update is not informed about this either (neither is the Frontend). A better experience is to forcibly cancel any in-flight Updates belonging to the History Shard that is closing. That way, the Frontend can re-issue the Update request (which will land on a new History Shard). The client won't even know that the History Shard was closed. However, if the retry happens towards the end of the Update timeout, the client's request might still time out after all. ## How did you test it? <!-- How have you verified this change? Tested locally? Added a unit test? Checked in staging env? --> Added unit tests and functional test. Before going live, this will have to be validated by thorough end-to-end testing. ## Potential risks <!-- Assuming the worst case, what can be broken when deploying this change to production? --> ### Code Complexity Since the workflow cache already has all the workflow contexts, I had considered adding a by-shardID index a method to iterate over them there. However, its cache implementation is based on `cache.Cache` (ie a generic cache) it would have been awkward to add it there. Therefore, I decided to track the workflow contexts in a separate place, the Finalizer, which adds to the complexity. ### Memory Leak There is no way to list the workflow contexts that belong to a History Shard. Therefore, a new "Finalizer" was introduced that maintains a list of cleanup callbacks: one callback per workflow context, grouped by History Shard. But since the workflow cache will eventually evict workflow contexts that are no longer needed, if the Finalizer holds on to these cleanup callbacks past the lifetime of the workflow context, the GC won't be able to free them from memory. Therefore, a lifecycle hook was introduced that removes any expired workflow contexts from the Finalizer. ### Delayed History Shard Closure The step to close the History Shard should not lock up if some/any of the workflow contexts cannot be cleared. To clear them, the lock for the workflow needs to be obtained. To prevent this from blocking indefinitely, a timeout was introduced. It's better to make sure the History Shard closes eventually than to clear all workflow contexts. PS: Logging has been added to be able to monitor the timeouts and completion rate of the Finalizer. PPS: If any production issues should occur, the Finalizer's cleanup step can be disabled entirely by setting the dynamic config for the timeout to zero. However, the registering/de-registering of callbacks cannot be disabled. ## Documentation <!-- Have you made sure this change doesn't falsify anything currently stated in `docs/`? If significant new behavior is added, have you described that in `docs/`? --> ## Is hotfix candidate? <!-- Is this PR a hotfix candidate or does it require a notification to be sent to the broader community? (Yes/No) -->
68 lines
1.9 KiB
Go
68 lines
1.9 KiB
Go
// The MIT License
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//
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// Copyright (c) 2020 Temporal Technologies Inc. All rights reserved.
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//
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// Copyright (c) 2020 Uber Technologies, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package definition
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import (
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"fmt"
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)
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type (
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// WorkflowKey is the combinations which represent a workflow
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WorkflowKey struct {
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NamespaceID string
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WorkflowID string
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RunID string
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}
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)
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// NewWorkflowKey create a new WorkflowKey
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func NewWorkflowKey(
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namespaceID string,
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workflowID string,
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runID string,
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) WorkflowKey {
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return WorkflowKey{
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NamespaceID: namespaceID,
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WorkflowID: workflowID,
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RunID: runID,
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}
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}
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func (k *WorkflowKey) GetNamespaceID() string {
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return k.NamespaceID
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}
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func (k *WorkflowKey) GetWorkflowID() string {
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return k.WorkflowID
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}
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func (k *WorkflowKey) GetRunID() string {
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return k.RunID
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}
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func (k *WorkflowKey) String() string {
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return fmt.Sprintf("%v/%v/%v", k.NamespaceID, k.WorkflowID, k.RunID)
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}
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