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https://issues.apache.org/jira/browse/CASSANDRA-14832?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16655798#comment-16655798
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Abhish Agarwal commented on CASSANDRA-14832:
--------------------------------------------
I agree with the approach here. There is a possibility of starvation given that
there is no memory available and multiple processes vie for it. Correct way is
to deduct the required memory before leaving it to free pool.
> Other threads can take all newly allocated BufferPool chunks before original
> and cause reallocation
> ---------------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-14832
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14832
> Project: Cassandra
> Issue Type: Improvement
> Reporter: 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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