[jira] [Resolved] (LUCENE-5928) WildcardQuery may has memory leak

["Uwe Schindler (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LUCENE-5928?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Uwe Schindler resolved LUCENE-5928.
-----------------------------------
    Resolution: Not a Problem
      Assignee: Uwe Schindler

Hi,
this is not an issue of WildcardQuery. This is also not related to used heap space. What you see differences in is in most cases a common misunderstanding about those 2 terms:

- Virtual Memory (VIRT): This is allocated address space, *it is not allocated memory*. On 64 bit platforms this is for free and is not limited by physical memory (it is not even related to each other). If you use mmap, VIRT is something like RES + up to 2 times the size of all open indexes. Internally the whole index is seen like a swap file to the OS kernel.
- Resident Memory (RES): This is size of heap space + size of direct memory. This is *allocated* memory, but may reside on swap, too.

By executing a Wildcard like "*:*" you just access the whole term dictionary and all positings lists, so they are accessed on disk and therefore loaded into file system cache. When using MMap, the space in file system cache is also shown in VIRT of the process, because the linux/windows kernel maps the file system memory into the address space. But its does not "waste" memory.

For more information, see: http://blog.thetaphi.de/2012/07/use-lucenes-mmapdirectory-on-64bit.html

> WildcardQuery may has memory leak
> ---------------------------------
>
>                 Key: LUCENE-5928
>                 URL: https://issues.apache.org/jira/browse/LUCENE-5928
>             Project: Lucene - Core
>          Issue Type: Bug
>          Components: core/search
>    Affects Versions: 4.9
>         Environment: SSD 1.5T, RAM 256G 10*10000
>            Reporter: Littlestar
>            Assignee: Uwe Schindler
>
> data 800G, records 15*10000*10000.
> one search thread.
> content:???
> content:*
> content:*1
> content:*2
> content:*3
> jvm heap=96G, but the jvm memusage over 130g?
> run more wildcard, use memory more....
> Does luence search/index use a lot of DirectMemory or Native Memory?
> I use -XX:MaxDirectMemorySize=4g, it does nothing better.
> Thanks.



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