From 9feadd3c6d71c1c48f7825d024ccf95d5d82606d Mon Sep 17 00:00:00 2001
From: Jack Cosgrove <59040827+jcosgrovehoppr@users.noreply.github.com>
Date: Thu, 19 Mar 2020 07:21:20 -0500
Subject: [PATCH] fix: Only permit web workers to be initialized once. (#1535)

---
 platform/viewer/src/utils/initWebWorkers.js      |  9 +++++++--
 platform/viewer/src/utils/initWebWorkers.test.js | 11 +++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/platform/viewer/src/utils/initWebWorkers.js b/platform/viewer/src/utils/initWebWorkers.js
index 6e8fb9107..8bbfa28d9 100644
--- a/platform/viewer/src/utils/initWebWorkers.js
+++ b/platform/viewer/src/utils/initWebWorkers.js
@@ -1,6 +1,8 @@
 import cornerstoneWADOImageLoader from 'cornerstone-wado-image-loader';
 
-export default function initWebWorkers() {  
+let initialized = false;
+
+export default function initWebWorkers() {
   const config = {
     maxWebWorkers: Math.max(navigator.hardwareConcurrency - 1, 1),
     startWebWorkersOnDemand: true,
@@ -13,5 +15,8 @@ export default function initWebWorkers() {
     },
   };
 
-  cornerstoneWADOImageLoader.webWorkerManager.initialize(config);
+  if (!initialized) {
+    cornerstoneWADOImageLoader.webWorkerManager.initialize(config);
+    initialized = true;
+  }
 }
diff --git a/platform/viewer/src/utils/initWebWorkers.test.js b/platform/viewer/src/utils/initWebWorkers.test.js
index ae6743eaf..cbd554a79 100644
--- a/platform/viewer/src/utils/initWebWorkers.test.js
+++ b/platform/viewer/src/utils/initWebWorkers.test.js
@@ -10,3 +10,14 @@ describe('initWebWorkers', () => {
     ).toHaveBeenCalled();
   });
 });
+
+describe('initWebWorkers', () => {
+  it("initializes cornerstoneWADOImageLoader's web workers only once", () => {
+    initWebWorkers();
+    initWebWorkers();
+
+    expect(
+      cornerstoneWADOImageLoader.webWorkerManager.initialize
+    ).toHaveBeenCalledTimes(1);
+  });
+});