From 542fbb4fcdb6657712fdea8d510bcf85bc5dfeb1 Mon Sep 17 00:00:00 2001
From: Ansis Brammanis <ansis@mapbox.com>
Date: Tue, 16 Jul 2019 17:43:30 -0400
Subject: [PATCH] fix #8481, unbounded memory growth in IE (#8490)

Cancellable requests to workers should never call back after they have
been cancelled.
---
 src/util/actor.js | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/util/actor.js b/src/util/actor.js
index edeb8b53e70..1e53d7c9a5e 100644
--- a/src/util/actor.js
+++ b/src/util/actor.js
@@ -56,12 +56,16 @@ class Actor {
         }, buffers);
         if (callback) {
             return {
-                cancel: () => this.target.postMessage({
-                    targetMapId,
-                    sourceMapId: this.mapId,
-                    type: '<cancel>',
-                    id: String(id)
-                })
+                cancel: () => {
+                    // Set the callback to null so that it never fires after the request is aborted.
+                    this.callbacks[id] = null;
+                    this.target.postMessage({
+                        targetMapId,
+                        sourceMapId: this.mapId,
+                        type: '<cancel>',
+                        id: String(id)
+                    });
+                }
             };
         }
     }