[core] fix a recursive mutex locking in task

[knopers8]

Fixes a bug reported in OCTRL-999.

The recursive locking happens in the following trace:

 5  0x000000000122c829 in github.com/AliceO2Group/Control/core/task.(*Task).GetParent
    at /home/alibuild/sw/BUILD/eb488922a0fabb8512ec137d3a765b22d2941067/Control-Core/go/src/github.com/AliceO2Group/Control/core/task/task.go:741
 6  0x000000000122597c in github.com/AliceO2Group/Control/core/task.(*Task).GetTraits
    at /home/alibuild/sw/BUILD/eb488922a0fabb8512ec137d3a765b22d2941067/Control-Core/go/src/github.com/AliceO2Group/Control/core/task/task.go:248
 7  0x000000000122a217 in github.com/AliceO2Group/Control/core/task.(*Task).SendEvent
    at /home/alibuild/sw/BUILD/eb488922a0fabb8512ec137d3a765b22d2941067/Control-Core/go/src/github.com/AliceO2Group/Control/core/task/task.go:528
    ```

[Copilot]

Pull Request Overview

This PR addresses a recursive mutex locking issue in the Task implementation by bypassing the traditional lock in the GetTraits method.

• Introduces a lock-free version of GetTraits named getTraits
• Updates the SendEvent method to use the new lock-free version

Comments suppressed due to low confidence (2)

core/task/task.go:258

• Please confirm that the parent's GetTaskTraits method is implemented as a lock-free or safe alternative, as calling it here may not resolve the recursive mutex locking issue if it internally acquires a lock.

return t.parent.GetTaskTraits()

core/task/task.go:255

• [nitpick] Consider renaming 'getTraits' to more clearly indicate it is a lock-free variant (e.g., 'getTraitsLockFree') to avoid potential confusion with the original GetTraits.

func (t *Task) getTraits() Traits {

[justonedev1]

I don't like how it is literally the same code for GetTraits() and getTraits() except t.parent part. I'd probably make getTraits(*parentRole) and call it from GetTraits, because the t.GetParent() usage in this case is not thread safe either way. We call it twice, so if there is a change of a parent from other goroutine, we might get different results on both calls due to race condition. With this change we will at least alway address the same parent, even if it changes half during the GetTraits call.

[knopers8]

did you mean something like this?