From cf963c06c388fb93ec99c6b0b7af09ea8658bc15 Mon Sep 17 00:00:00 2001
From: Eugene Dudnyk <eugene.dudnyk@innomos.com>
Date: Sun, 21 May 2017 12:49:03 +0200
Subject: [PATCH] #1909: Crash on multiple concurrent downloads when accessing
 self.URLOperations dictionary.

---
 SDWebImage/SDWebImageDownloader.m | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/SDWebImage/SDWebImageDownloader.m b/SDWebImage/SDWebImageDownloader.m
index f6481612..bf7a6d94 100644
--- a/SDWebImage/SDWebImageDownloader.m
+++ b/SDWebImage/SDWebImageDownloader.m
@@ -230,11 +230,13 @@
 
             __weak SDWebImageDownloaderOperation *woperation = operation;
             operation.completionBlock = ^{
-              SDWebImageDownloaderOperation *soperation = woperation;
-              if (!soperation) return;
-              if (self.URLOperations[url] == soperation) {
-                  [self.URLOperations removeObjectForKey:url];
-              };
+				dispatch_barrier_sync(self.barrierQueue, ^{
+					SDWebImageDownloaderOperation *soperation = woperation;
+					if (!soperation) return;
+					if (self.URLOperations[url] == soperation) {
+						[self.URLOperations removeObjectForKey:url];
+					};
+				});
             };
         }
         id downloadOperationCancelToken = [operation addHandlersForProgress:progressBlock completed:completedBlock];