[jira] [Resolved] (IMPALA-9291) MemTracker's TryConsume() should behave consistent with Consume()/Release()

["Zoltán Borók-Nagy (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-9291?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zoltán Borók-Nagy resolved IMPALA-9291.
---------------------------------------
    Fix Version/s: Impala 3.4.0
       Resolution: Fixed

> MemTracker's TryConsume() should behave consistent with Consume()/Release()
> ---------------------------------------------------------------------------
>
>                 Key: IMPALA-9291
>                 URL: https://issues.apache.org/jira/browse/IMPALA-9291
>             Project: IMPALA
>          Issue Type: Bug
>            Reporter: Zoltán Borók-Nagy
>            Assignee: Zoltán Borók-Nagy
>            Priority: Major
>             Fix For: Impala 3.4.0
>
>
> Impala's MemTracker tracks allocated memory. MemTracker::Consume() is meant to be used in tandem with memory allocations and MemTracker::Release() is for de-allocations.
> However, both supports negative values, in this case MemTracker::Consume(negative_val) will invoke MemTracker::Release(*-*negative_val), and vica versa.
> On the other hand, TryConsume() is a no-op for values less than zero. This causes problems in the following scenario:
>  
> {noformat}
> TryConsume(-42); // no-op, returns true which means SUCCESS
> Release(-42); // => Consume(42)
> {noformat}
> Later when the mem tracker gets closed it will think there is 42 bytes of unallocated memory.
> Either we shouldn't allow negative values in Consume()/TryConsume()/Release(), or TryConsume() should invoke Release() in this case instead of doing nothing.



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