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Jörg Rathlev commented on SOLR-10506: ------------------------------------- Oh, right, good point! So, the SchemaWatcher needs to keep a strong reference to the ZkIndexSchemaReader but then that should be cleaned up in the SolrCore's onClose hook. I'll try to run another test with a memory profiler in the next couple of days to see if that solves the issue. > Possible memory leak upon collection reload > ------------------------------------------- > > Key: SOLR-10506 > URL: https://issues.apache.org/jira/browse/SOLR-10506 > Project: Solr > Issue Type: Bug > Security Level: Public(Default Security Level. Issues are Public) > Components: Server > Affects Versions: 6.5 > Reporter: Torsten Bøgh Köster > Attachments: solr_collection_reload_13_cores.png, > solr_gc_path_via_zk_WatchManager.png > > > 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 (see screenshot 1). > Each {{SolrCore}} instance holds a single path with strong references to the > gc root via a `Watcher` in `ZkIndexSchemaReader` (see screenshot 2). The > {{ZkIndexSchemaReader}} registers a close hook in the {{SolrCore}} but the > Zookeeper is not removed upon core close. > We supplied a Github Pull Request > (https://github.com/apache/lucene-solr/pull/197) 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 ... -- This message was sent by Atlassian JIRA (v6.3.15#6346) --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org