From 915e5826efba758c42aefeeab69499ddcdd9cf50 Mon Sep 17 00:00:00 2001
From: Nick Lockwood <nicklockwood@fb.com>
Date: Wed, 10 Feb 2016 12:48:41 -0800
Subject: [PATCH] Restricted image decoding to 2 simultaneous threads

Reviewed By: zjj010104

Differential Revision: D2922292

fb-gh-sync-id: eddd47d02fc721acc1da69e7483c6570997320b5
shipit-source-id: eddd47d02fc721acc1da69e7483c6570997320b5
---
 Libraries/Image/RCTImageLoader.m | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/Libraries/Image/RCTImageLoader.m b/Libraries/Image/RCTImageLoader.m
index 0d7b06f5c1d578..22bffa4a3d2661 100644
--- a/Libraries/Image/RCTImageLoader.m
+++ b/Libraries/Image/RCTImageLoader.m
@@ -38,6 +38,7 @@ @implementation RCTImageLoader
 {
   NSArray<id<RCTImageURLLoader>> *_loaders;
   NSArray<id<RCTImageDataDecoder>> *_decoders;
+  NSOperationQueue *_imageDecodeQueue;
   dispatch_queue_t _URLCacheQueue;
   NSURLCache *_URLCache;
 }
@@ -474,7 +475,13 @@ - (RCTImageLoaderCancellationBlock)decodeImageDataWithoutClipping:(NSData *)data
                        completionHandler:completionHandler];
   } else {
 
-    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+    // Serialize decoding to prevent excessive memory usage
+    if (!_imageDecodeQueue) {
+      _imageDecodeQueue = [NSOperationQueue new];
+      _imageDecodeQueue.name = @"com.facebook.react.ImageDecoderQueue";
+      _imageDecodeQueue.maxConcurrentOperationCount = 2;
+    }
+    [_imageDecodeQueue addOperationWithBlock:^{
       if (cancelled) {
         return;
       }
@@ -501,7 +508,7 @@ - (RCTImageLoaderCancellationBlock)decodeImageDataWithoutClipping:(NSData *)data
         NSError *finalError = RCTErrorWithMessage(errorMessage);
         completionHandler(finalError, nil);
       }
-    });
+    }];
 
     return ^{
       OSAtomicOr32Barrier(1, &cancelled);