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https://issues.apache.org/jira/browse/CASSANDRA-14832?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Benedict updated CASSANDRA-14832:
---------------------------------
    Summary: BufferPool: allocating thread for new chunks should acquire 
directly  (was: Other threads can take all newly allocated BufferPool chunks 
before original and cause reallocation)

> BufferPool: allocating thread for new chunks should acquire directly
> --------------------------------------------------------------------
>
>                 Key: CASSANDRA-14832
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-14832
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Jon Meredith
>            Assignee: Jon Meredith
>            Priority: Minor
>
> When BufferPool does not have any free Chunks to satisfy a request, the 
> calling thread allocates a new large block of memory which it breaks up into 
> chunks and adds to the free chunks queue, then pulls from the queue to 
> satisfy it's own allocation.
> If enough other threads request chunks it is possible for the queue to be 
> exhausted before the original allocating thread is able to pull of it's own 
> allocation, causing the original allocator to loop and attempt to allocate 
> more memory.  This is unfair to the original caller and may cause it to block 
> on a system call to allocate more memory.
> Instead of the current behavior, allocateMoreChunks could hold back one of 
> the chunks and return it to the caller instead so that it will at most call 
> allocate once.
>  



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