[infinispan-issues] [JBoss JIRA] (ISPN-3877) SingleFileStore continues to consume space on the disk even if the free entries at end of the file are not in use. This space can be released back to the filesystem

[Rajesh Jangam (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-3877?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12935891#comment-12935891 ] 

Rajesh Jangam commented on ISPN-3877:
-------------------------------------

Hello Mircea,

Thanks for your response. I have attached a small test program that can show the difference in the space usage.
On my machine, 
a. with the original SingleFileStore version, the disk consumption reaches to around 10-11 MB and stays there.
b. with the modified (patched version), the disk consumption reaches to around 10-11MB, but after the purge cycles kick-in, the file size remains below 500KB consistently.

I am going to attach a pull request for this issue. So, please review the diff from there.
After your review, can you also please let me know if this enhancement seems ok from your point of view?

The overhead on the purge cycle because of our truncation logic is very minimal (around few tens of milli-seconds).

Also, I am going to create another JIRA issue for another enhancement related to coalescing adjacent free entries. 

Thanks,
Rajesh

                
> SingleFileStore continues to consume space on the disk even if the free entries at end of the file are not in use. This space can be released back to the filesystem
> --------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: ISPN-3877
>                 URL: https://issues.jboss.org/browse/ISPN-3877
>             Project: Infinispan
>          Issue Type: Patch
>          Components: Loaders and Stores
>    Affects Versions: 6.0.0.Final
>         Environment: Oracle JDK 1.7, Windows Server 2008 R2 x64
>            Reporter: Rajesh Jangam
>            Assignee: Galder Zamarreño
>         Attachments: PersistentQueue.java
>
>
> We are testing the latest Infinispan 6.0 SingleFileStore version for our application.
> We tend to create a lot of entries in the store and remove them when not required.
> However, what we have observed is that the size of the file keeps on increasing as more data is being added/removed and that it does not get reclaimed.
>  
> This was not seen with earlier versions like 5.3.0. There the size of the cache folder would reduce as entries got removed.
> We have attempted to create a fix for this issue and tested it in our environment. It keeps the space usage under control as compared to the original implementation.
> As a part of this fix, we truncate the file (as a part of purge cycle) if there are free entries found towards the end of the file. Also these free entries are removed from the freeList.

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