[jira] [Comment Edited] (IGNITE-11156) FreeLists are overflowed with pages with almost no free space left

["Pavel Pereslegin (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IGNITE-11156?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16926524#comment-16926524 ] 

Pavel Pereslegin edited comment on IGNITE-11156 at 9/10/19 11:17 AM:
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Hello [~ivan.glukos].

Maybe it still worth to include this improvement because at least it should slightly reduce memory consumption to maintain one redundant bucket of the free list (possibly the “largest” one)?

 


was (Author: xtern):
Hello [~ivan.glukos]!

Maybe it still makes sense to include (merge) this improvement, because at least it should slightly reduce memory consumption to maintain one redundant bucket of the free list (possibly the “largest” one). Also, the code will be cleaner (and cleaver) apparently.

How do you think?

> FreeLists are overflowed with pages with almost no free space left
> ------------------------------------------------------------------
>
>                 Key: IGNITE-11156
>                 URL: https://issues.apache.org/jira/browse/IGNITE-11156
>             Project: Ignite
>          Issue Type: Improvement
>            Reporter: Ivan Rakov
>            Assignee: Ivan Rakov
>            Priority: Major
>             Fix For: 2.8
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> {code:java}
>     /** */
>     private static final int MIN_PAGE_FREE_SPACE = 8;
> {code}
> If data page has 8 unused bytes or more, it will be stored in a free list. As result, free lists mostly contain "free pages" that are actually useless: pair of (boolean, boolean) takes approximately 50 bytes. I think, we'll increase this constant to something like 40, memory will be used more efficiently and WAL usage will decrease in result.



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