[FLINK-24294] Resources leak in the StreamTask constructor

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.14.0
• Fix Version/s: 1.15.0
• Component/s: Runtime / Task
• Labels: pull-request-available
• Assignee: Anton Kalashnikov
• Reporter: Anton Kalashnikov
• Created: 15/Sep/21 09:57
• Updated: 25/Nov/21 08:01
• Resolved: 25/Nov/21 08:01

Description

Since we are initializing a lot of resources in the StreamTask constructor like RecordWriter, timerServices, etc. it is possible that some of these resources remain open if the exception happens below the initialization in the same constructor.
So in my opinion, we have two choices here:

• Avoiding allocation of resources in the constructor which allows us to do something like:

  StreamTask task = new StreamTask(); //no leaks if it fails
  try { 
    task.init();
    ....
  } finally {
    task.cleanUp();
  }
  

• or we can rewrite a code in such a way that exception in any constructor(ex. StreamTask) guarantee releasing the earlier allocated resources in this constructor. But it is not so easy to implement(see. initialization of recordWriter in StreamTask constructor)

So perhaps it makes sense to separate creating object from initialization(allocation resources)

Issue Links

• links to: GitHub Pull Request #17701