From a55823ed83b59ad962356c0281109c07a61e59e1 Mon Sep 17 00:00:00 2001
From: Patrik Ivarsson <patrik.ivarsson@avanza.se>
Date: Mon, 5 Sep 2022 16:54:38 +0200
Subject: [PATCH] TP-1222: Make getInstance() thread-safe with double-checked
 locking

---
 .../com/avanza/gs/test/JVMGlobalGigaSpacesManager.java | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/gs-test-core/src/main/java/com/avanza/gs/test/JVMGlobalGigaSpacesManager.java b/gs-test-core/src/main/java/com/avanza/gs/test/JVMGlobalGigaSpacesManager.java
index c5da1d8..a8984b2 100644
--- a/gs-test-core/src/main/java/com/avanza/gs/test/JVMGlobalGigaSpacesManager.java
+++ b/gs-test-core/src/main/java/com/avanza/gs/test/JVMGlobalGigaSpacesManager.java
@@ -22,12 +22,16 @@
  */
 public final class JVMGlobalGigaSpacesManager {
 
-	private static InMemoryGigaSpacesManager instance;
+	private static volatile InMemoryGigaSpacesManager instance;
 
 	private static InMemoryGigaSpacesManager getInstance() {
 		if (instance == null) {
-			instance = new InMemoryGigaSpacesManager();
-			Runtime.getRuntime().addShutdownHook(new Thread(() -> instance.close()));
+			synchronized (JVMGlobalGigaSpacesManager.class) {
+				if (instance == null) {
+					instance = new InMemoryGigaSpacesManager();
+					Runtime.getRuntime().addShutdownHook(new Thread(() -> instance.close()));
+				}
+			}
 		}
 		return instance;
 	}