[FLINK-14857] Deprecate checkpoint lock from the Operators API

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.9.1
• Fix Version/s: 1.10.0
• Component/s: Runtime / Task
• Labels: pull-request-available

Release Note

Deprecated {{getCheckpointLock}} method of the {{org.apache.flink.streaming.runtime.tasks.StreamTask}} class.

Users should use {{MailboxExecutor}} to run actions that require synchronization with the task's thread (e.g. collecting output produced by an external thread). {{MailboxExecutor#yield}} or {{MailboxExecutor#tryYield}} methods can be used for actions that should give control to other actions temporarily, if the current operator is blocked.

{{MailboxExecutor}} can be accessed by using {{YieldingOperatorFactory}}. Example usage can be found in the {{AsyncWaitOperator}}.

• Assignee: Roman Khachatryan
• Reporter: Roman Khachatryan
• Created: 19/Nov/19 11:16
• Updated: 11/Feb/20 12:03
• Resolved: 06/Dec/19 10:58

Description

Drop `this.checkpointLock = getContainingTask().getCheckpointLock();` access (used for example in `ContinuousFileReaderOperator`).

Redirect users to the mailbox (enqueuing/yielding).

Issue Links

• relates to: FLINK-12484 Drop unnecessary locking for code-paths that now use the mailbox
• links to: GitHub Pull Request #10252
• links to: GitHub Pull Request #10441