From b33010a24cd645d9bf433974daa71a21c17c49f2 Mon Sep 17 00:00:00 2001
From: kimchy <kimchy@gmail.com>
Date: Tue, 23 Nov 2010 03:51:38 +0200
Subject: [PATCH] document the heap dump options

---
 bin/elasticsearch.in.sh | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/bin/elasticsearch.in.sh b/bin/elasticsearch.in.sh
index 99ca3e6d60e..041f266ee7e 100644
--- a/bin/elasticsearch.in.sh
+++ b/bin/elasticsearch.in.sh
@@ -7,9 +7,14 @@ if [ "x$ES_MAX_MEM" = "x" ]; then
     ES_MAX_MEM=1g
 fi
 
-# Arguments to pass to the JVM
+# min and max heap sizes should be set to the same value to avoid
+# stop-the-world GC pauses during resize, and so that we can lock the
+# heap in memory on startup to prevent any of it from being swapped
+# out.
 JAVA_OPTS="$JAVA_OPTS -Xms${ES_MIN_MEM}"
 JAVA_OPTS="$JAVA_OPTS -Xmx${ES_MAX_MEM}"
+
+# reduce the per-thread stack size
 JAVA_OPTS="$JAVA_OPTS -Xss128k"
 
 JAVA_OPTS="$JAVA_OPTS -Djline.enabled=true"
@@ -29,5 +34,8 @@ JAVA_OPTS="$JAVA_OPTS -XX:MaxTenuringThreshold=1"
 JAVA_OPTS="$JAVA_OPTS -XX:CMSInitiatingOccupancyFraction=75"
 JAVA_OPTS="$JAVA_OPTS -XX:+UseCMSInitiatingOccupancyOnly"
 
+# Causes the JVM to dump its heap on OutOfMemory.
 JAVA_OPTS="$JAVA_OPTS -XX:+HeapDumpOnOutOfMemoryError"
-JAVA_OPTS="$JAVA_OPTS -XX:HeapDumpPath=$ES_HOME/work/heap"
+# The path to the heap dump location, note directory must exists and have enough
+# space for a full heap dump.
+#JAVA_OPTS="$JAVA_OPTS -XX:HeapDumpPath=$ES_HOME/logs/heapdump.hprof"