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https://issues.apache.org/jira/browse/SOLR-3685?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13423796#comment-13423796
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Uwe Schindler commented on SOLR-3685:
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OK, I wanted to come back:
>From what I see, 96 MB of heap is very few for Solr. Tests are running with
>-Xmx512. But regarding memory consumtion (Java's heap OOMs), Mark Miller might
>know better.
But Solr will not use all available RAM, as you are on 64 bit Java, Solr
defaults to MMapDirectory - I recommend to read:
http://blog.thetaphi.de/2012/07/use-lucenes-mmapdirectory-on-64bit.html
It will allocate from the system only heap + what Java itsself needs.
Everything else is only allocated as adress space to directly acces file system
cache. So the real memory usage of Solr is not what "top" reports in column
"VIRT" but in column "RES" (resident memory). VIRT can be much higher
(multiples of system RAM) with MMapDirectoy, as it only shows virtual address
space allocated. This cannot cause Kernel-OOM to get active and kill processes,
if that happens you have too few RAM for kernel, Solr + tools, sorry.
> solrcloud crashes on startup due to excessive memory consumption
> ----------------------------------------------------------------
>
> Key: SOLR-3685
> URL: https://issues.apache.org/jira/browse/SOLR-3685
> Project: Solr
> Issue Type: Bug
> Components: replication (java), SolrCloud
> Affects Versions: 4.0-ALPHA
> Environment: Debian GNU/Linux Squeeze 64bit
> Solr 5.0-SNAPSHOT 1365667M - markus - 2012-07-25 19:09:43
> Reporter: Markus Jelsma
> Priority: Critical
> Fix For: 4.1
>
> Attachments: info.log
>
>
> There's a serious problem with restarting nodes, not cleaning old or unused
> index directories and sudden replication and Java being killed by the OS due
> to excessive memory allocation. Since SOLR-1781 was fixed index directories
> get cleaned up when a node is being restarted cleanly, however, old or unused
> index directories still pile up if Solr crashes or is being killed by the OS,
> happening here.
> We have a six-node 64-bit Linux test cluster with each node having two
> shards. There's 512MB RAM available and no swap. Each index is roughly 27MB
> so about 50MB per node, this fits easily and works fine. However, if a node
> is being restarted, Solr will consistently crash because it immediately eats
> up all RAM. If swap is enabled Solr will eat an additional few 100MB's right
> after start up.
> This cannot be solved by restarting Solr, it will just crash again and leave
> index directories in place until the disk is full. The only way i can restart
> a node safely is to delete the index directories and have it replicate from
> another node. If i then restart the node it will crash almost consistently.
> I'll attach a log of one of the nodes.
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