Setting number of sharedArenaMaxPermits to 1 (opensearch-project#19503)

Signed-off-by: Ankit Jain <jainankitk@apache.org>

Author: jainankitk

CHANGELOG.md

@@ -101,6 +101,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Implement SslHandler retrieval logic for transport-reactor-netty4 plugin ([#19458](https://github.com/opensearch-project/OpenSearch/pull/19458))
 - Cache serialised cluster state based on cluster state version and node version.([#19307](https://github.com/opensearch-project/OpenSearch/pull/19307))
 - Fix stats API in store-subdirectory module's SubdirectoryAwareStore ([#19470](https://github.com/opensearch-project/OpenSearch/pull/19470))
+- Setting number of sharedArenaMaxPermits to 1 ([#19503](https://github.com/opensearch-project/OpenSearch/pull/19503))
 - Handle negative search request nodes stats ([#19340](https://github.com/opensearch-project/OpenSearch/pull/19340))
 - Remove unnecessary iteration per-shard in request cache cleanup ([#19263](https://github.com/opensearch-project/OpenSearch/pull/19263))
 

distribution/src/config/jvm.options

@@ -86,3 +86,8 @@ ${error.file}
 
 21-:-javaagent:agent/opensearch-agent.jar
 21-:--add-opens=java.base/java.nio=org.apache.arrow.memory.core,ALL-UNNAMED
+
+# For cases with high memory-mapped file counts, a lower value can improve stability and
+# prevent issues like "leaked" maps or performance degradation. A value of 1 effectively
+# disables the shared Arena pooling and uses a confined Arena for each MMapDirectory
+-Dorg.apache.lucene.store.MMapDirectory.sharedArenaMaxPermits=1