GitHub user tboeghk opened a pull request:
https://github.com/apache/lucene-solr/pull/190
[SOLR-10506] Fixes a memory leak in zk schema watching
Upon manual Solr Collection reloading, references to the closed `SolrCore`
are not fully removed by the garbage collector as a strong reference to the
`ZkIndexSchemaReader` is held in a ZooKeeper `Watcher` that watches for schema
changes.
In our case, this leads to a massive memory leak as managed resources are
still referenced by the closed `SolrCore`. Our Solr cloud environment utilizes
rather large managed resources (synonyms, stopwords). To reproduce, we fired
out environment up and reloaded the collection 13 times. As a result we fully
exhausted our heap. A closer look with the Yourkit profiler revealed 13
`SolrCore` instances, still holding strong references to the garbage collection
root.
Each `SolrCore` instance holds a single path with strong references to the
gc root via a `Watcher` in `ZkIndexSchemaReader`. The `ZkIndexSchemaReader`
registers a close hook in the `SolrCore` but the Zookeeper is not removed upon
core close.
We supplied this Github Pull Request that extracts the zookeeper `Watcher`
as a static inner class. To eliminate the memory leak, the schema reader is
held inside a `WeakReference` and the reference is explicitly removed on core
close.
Initially I wanted to supply a test case but unfortunately did not find a
good starting point ...
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/shopping24/lucene-solr branch_6_5
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/lucene-solr/pull/190.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #190
----
commit 9a5abee7e9b431ba0c2e0d432dc33b1919fa4f40
Author: Torsten Bøgh KoÌster <[email protected]>
Date: 2017-04-18T09:43:52Z
Fixes a memory leak in zk schema watching
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