From 9e8c51b70d44c124bd3008cb4bb7c52fcb502f77 Mon Sep 17 00:00:00 2001
From: mikemccand <mail@mikemccandless.com>
Date: Sun, 28 Sep 2014 12:30:48 -0400
Subject: [PATCH] fix concurrency bug in index throttling

---
 .../elasticsearch/index/engine/internal/InternalEngine.java   | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main/java/org/elasticsearch/index/engine/internal/InternalEngine.java b/src/main/java/org/elasticsearch/index/engine/internal/InternalEngine.java
index df38b6d68ff..381d9544a16 100644
--- a/src/main/java/org/elasticsearch/index/engine/internal/InternalEngine.java
+++ b/src/main/java/org/elasticsearch/index/engine/internal/InternalEngine.java
@@ -1735,7 +1735,7 @@ public class InternalEngine extends AbstractIndexShardComponent implements Engin
         }
 
         @Override
-        public void beforeMerge(OnGoingMerge merge) {
+        public synchronized void beforeMerge(OnGoingMerge merge) {
             if (numMergesInFlight.incrementAndGet() > maxNumMerges) {
                 if (isThrottling.getAndSet(true) == false) {
                     logger.info("now throttling indexing: numMergesInFlight={}, maxNumMerges={}", numMergesInFlight, maxNumMerges);
@@ -1745,7 +1745,7 @@ public class InternalEngine extends AbstractIndexShardComponent implements Engin
         }
 
         @Override
-        public void afterMerge(OnGoingMerge merge) {
+        public synchronized void afterMerge(OnGoingMerge merge) {
             if (numMergesInFlight.decrementAndGet() < maxNumMerges) {
                 if (isThrottling.getAndSet(false)) {
                     logger.info("stop throttling indexing: numMergesInFlight={}, maxNumMerges={}", numMergesInFlight, maxNumMerges);