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From Ilya Korol <llivezk...@gmail.com>
Subject Re: Proposal to remove explicit "GC disable" startup suggestion
Date Sun, 16 May 2021 12:50:09 GMT
In some circumstances there could be a state when direct buffers 
(instantiated for IO purposes) hold too many memory and to get this 
memory back JVM calls System.gc() (as was mentioned earlier by Ivan 
Daschinsky):

ByteBuffer.allocateDirect(capacity)
     new DirectButeBuffer(capacity)
         Bits.reserveMemory(size, cap)
...
             System.gc() // if optimistic attempts to reserve required 
memory failed

See also:
[1] 
http://www.mastertheboss.com/other/java-stuff/troubleshooting-outofmemoryerror-direct-buffer-memory

See

16.05.2021 01:21, Valentin Kulichenko пишет:
> Hi Ilya,
>
> Out of curiosity - what are the potential problems with memory buffers that
> you're referring to?
>
> -Val
>
> On Fri, May 14, 2021 at 5:06 AM Ilya Korol <llivezking@gmail.com> wrote:
>
>> Hi, everyone.
>>
>> There is a proposal to remove suggestion that user should disable
>> explicit GC calls in https://issues.apache.org/jira/browse/IGNITE-14720.
>>
>> Nowadays people usually don't use this facility directly without huge
>> need (at least we hope so), so this suggestion doesn't bring much
>> profit, but instead could lead to potential problems with reclaiming
>> memory used by direct memory buffers.
>>
>> I'm going to fix this.
>>
>> Is there any objections (suggestions)?
>>
>>

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