From aca95a1ec6a28b161e00c377e9929efbd3a9c277 Mon Sep 17 00:00:00 2001
From: Guna Sekhar Dora Kovvuru <gunasekhar.dora3@gmail.com>
Date: Sun, 7 Jun 2020 15:44:30 +0530
Subject: [PATCH] SOLR-13492: perform explicit GC concurrently (#1370)

---
 solr/CHANGES.txt     | 3 +++
 solr/bin/solr        | 3 ++-
 solr/bin/solr.cmd    | 3 ++-
 solr/bin/solr.in.cmd | 1 +
 solr/bin/solr.in.sh  | 1 +
 5 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/solr/CHANGES.txt b/solr/CHANGES.txt
index 2924a6546e1..a9da21670b9 100644
--- a/solr/CHANGES.txt
+++ b/solr/CHANGES.txt
@@ -297,6 +297,9 @@ Other Changes
 
 * SOLR-14480: Fix or suppress warnings in solr/cloud/api (Erick Erickson)
 
+* SOLR-13492: Ensure explicit GCs are concurrent by adding '+ExplicitGCInvokesConcurrent'.
+  (Guna Sekhar Dora, Shawn Heisey, Munendra S N)
+
 ==================  8.5.2 ==================
 
 Consult the LUCENE_CHANGES.txt file for additional, low level, changes in this release.
diff --git a/solr/bin/solr b/solr/bin/solr
index 87f56bc4fcc..1bbe3b388d8 100755
--- a/solr/bin/solr
+++ b/solr/bin/solr
@@ -2152,7 +2152,8 @@ function start_solr() {
         '-XX:+ParallelRefProcEnabled' \
         '-XX:MaxGCPauseMillis=250' \
         '-XX:+UseLargePages' \
-        '-XX:+AlwaysPreTouch')
+        '-XX:+AlwaysPreTouch' \
+        '-XX:+ExplicitGCInvokesConcurrent')
   else
     GC_TUNE=($GC_TUNE)
   fi
diff --git a/solr/bin/solr.cmd b/solr/bin/solr.cmd
index 8dddbc90c98..4b4d8132c5b 100755
--- a/solr/bin/solr.cmd
+++ b/solr/bin/solr.cmd
@@ -1212,7 +1212,8 @@ IF "%GC_TUNE%"=="" (
     -XX:+ParallelRefProcEnabled ^
     -XX:MaxGCPauseMillis=250 ^
     -XX:+UseLargePages ^
-    -XX:+AlwaysPreTouch
+    -XX:+AlwaysPreTouch ^
+    -XX:+ExplicitGCInvokesConcurrent
 )
 
 if !JAVA_MAJOR_VERSION! GEQ 9  (
diff --git a/solr/bin/solr.in.cmd b/solr/bin/solr.in.cmd
index 48a0a60860a..6aa392cdfea 100755
--- a/solr/bin/solr.in.cmd
+++ b/solr/bin/solr.in.cmd
@@ -35,6 +35,7 @@ REM set GC_LOG_OPTS=-verbose:gc -XX:+PrintHeapAtGC -XX:+PrintGCDetails -XX:+Prin
 
 REM Various GC settings have shown to work well for a number of common Solr workloads.
 REM See solr.cmd GC_TUNE for the default list.
+REM set GC_TUNE=-XX:+ExplicitGCInvokesConcurrent
 REM set GC_TUNE=-XX:SurvivorRatio=4
 REM set GC_TUNE=%GC_TUNE% -XX:TargetSurvivorRatio=90
 REM set GC_TUNE=%GC_TUNE% -XX:MaxTenuringThreshold=8
diff --git a/solr/bin/solr.in.sh b/solr/bin/solr.in.sh
index b336a033749..6774d1245a9 100644
--- a/solr/bin/solr.in.sh
+++ b/solr/bin/solr.in.sh
@@ -47,6 +47,7 @@
 
 # These GC settings have shown to work well for a number of common Solr workloads
 #GC_TUNE=" \
+#-XX:+ExplicitGCInvokesConcurrent \
 #-XX:SurvivorRatio=4 \
 #-XX:TargetSurvivorRatio=90 \
 #-XX:MaxTenuringThreshold=8 \