Background Assets The online Appstore crashed : EXC_BREAKPOINT

Background Assets are integrated into our online Appstore. However, after launching the APP, we collected many crashes of Background Assets framework through our crash system.

1、BADownloadManager.sharedManager.fetchCurrentDownloadsWithCompletionHandler. Then, I am reinitiating the tasks through startForegroundDownload. However, occasionally there is a crash with EXC_BREAKPOINT

[BADownloadManager.sharedManager fetchCurrentDownloadsWithCompletionHandler:^(NSArray<BADownload *> * _Nonnull downloads, NSError * _Nullable error) {        
        if (error){            
            return;
        }
        for (BADownload *download in downloads) {
            if ([urlList containsObject:download.identifier]){
                if (download.state == BADownloadStateFailed) {                    
                    return;
                }
                NSError *downloadError;
                BOOL succes = [BADownloadManager.sharedManager startForegroundDownload:download error:&downloadError];
                if (downloadError) {
                    LogError(BADownloadLog,@"startForegroundDownload url:%@ error:%@",download.identifier,downloadError);
                }else if(succes){
                    LogInfo(BADownloadLog,@"startForegroundDownload:%@",download.identifier);
                    [self addDowdloadingUrl:download.identifier];
                }
            }
        }
    }];

The following crashes exist:

Thread 3 (crashed)
 0  BackgroundAssets!-[BADownloadManager startForegroundDownload:error:] + 0x100
    Found by: given as instruction pointer in context
 1  BackgroundAssets!-[BADownloadManager startForegroundDownload:error:] + 0xe0
    Found by: previous frame's frame pointer
 2  YYMobile!__46-[YYBADownloadManager executeDownload:finish:]_block_invoke [YYBADownloadManager.m : 180 + 0xc]
    Found by: previous frame's frame pointer
 3  libdispatch.dylib!_dispatch_call_block_and_release + 0x1c
    Found by: previous frame's frame pointer
 4  libdispatch.dylib!_dispatch_client_callout + 0x10
    Found by: previous frame's frame pointer
 5  libdispatch.dylib!_dispatch_lane_serial_drain + 0x298
    Found by: previous frame's frame pointer
 6  libdispatch.dylib!_dispatch_lane_invoke + 0x17c
    Found by: previous frame's frame pointer
 7  libdispatch.dylib!_dispatch_workloop_worker_thread + 0x284
    Found by: previous frame's frame pointer
 8  libsystem_pthread.dylib!_pthread_wqthread + 0x11c
    Found by: previous frame's frame pointer

See attachment "iOS.crash" for the complete crash file.

Ask what, do I need to use exclusive control when accessing BADownload?

2、Handling failed callbacks in background download extension, rearranging necessary resources crashed

- (void)backgroundDownload:(BADownload *)download failedWithError:(NSError *)error
{
    // Extension was woken because a download failed.
    // A download can be rescheduled with BADownloadManager if necessary.
    if (![download isKindOfClass:[BAURLDownload class]]) {
        return;
    }
    if (download.isEssential){
        BADownload *nonEssential = [download copyAsNonEssential];
        [BADownloadManager.sharedManager scheduleDownload:nonEssential error:nil];
    }
}

Have a crash:

hread 1 Crashed:
0   BackgroundAssets              	0x0000000245b47dac -[BADownload setPriority:] + 176 (BADownload.m:249)
1   BackgroundAssets              	0x0000000245b47bb4 -[BADownload copyWithZone:] + 188 (BADownload.m:217)
2   BackgroundAssets              	0x0000000245b46db0 -[BAURLDownload copyWithZone:] + 52 (BAURLDownload.m:127)
3   BackgroundAssets              	0x0000000245b47f7c -[BADownload copyAsNonEssential] + 20 (BADownload.m:368)
4   YYBackgroundDownload          	0x0000000100de8a88 0x100de4000 + 19080
5   BackgroundAssets              	0x0000000245b3fd50 __88-[BADownloaderExtensionConnection backgroundDownload:failedWithError:completionHandler:]_block_invoke + 56 (BADownloaderExtensionConnection.m:178)
6   libdispatch.dylib             	0x00000001d8080320 _dispatch_call_block_and_release + 32 (init.c:1518)
7   libdispatch.dylib             	0x00000001d8081eac _dispatch_client_callout + 20 (object.m:560)
8   libdispatch.dylib             	0x00000001d8089534 _dispatch_lane_serial_drain + 668 (inline_internal.h:2640)
9   libdispatch.dylib             	0x00000001d808a0a4 _dispatch_lane_invoke + 384 (queue.c:3966)
10  libdispatch.dylib             	0x00000001d8094cdc _dispatch_workloop_worker_thread + 648 (queue.c:6913)
11  libsystem_pthread.dylib       	0x0000000230547ddc _pthread_wqthread + 288 (pthread.c:2618)
12  libsystem_pthread.dylib       	0x0000000230547b7c start_wqthread + 8 (:-1)

Details see attachment

You posted two crash reports. The first is a non-Apple one, and I can’t do anything with that. The second is an Apple crash report, which is cool.

Consider this:

Exception Type:  EXC_BREAKPOINT (SIGTRAP)

This usually means that the app trapped, that is, detected some bad state and crashed deliberately. The crashing thread backtrace looks like this:

Thread 1 name:
Thread 1 Crashed:
0 BackgroundAssets     … -[BADownload setPriority:] + 176 (BADownload.m:249)
1 BackgroundAssets     … -[BADownload copyWithZone:] + 188 (BADownload.m:217)
2 BackgroundAssets     … -[BAURLDownload copyWithZone:] + 52 (BAURLDownload.m:127)
3 BackgroundAssets     … -[BADownload copyAsNonEssential] + 20 (BADownload.m:368)
4 YYBackgroundDownload … 0x100de4000 + 19080
5 BackgroundAssets     … __88-[BADownloaderExtensionConnection backgroundDownload:failedWithError:completionHandler:]_block_invoke + 56 (BADownloaderExtensionConnection.m:178)
6 libdispatch.dylib    … _dispatch_call_block_and_release + 32 (init.c:1518)

The most likely cause of the trap is that, in frame 0, that is -[BADownload setPriority:], the priority is set to a value outside of the range BADownloaderPriorityMin through BADownloaderPriorityMax. Frames 1 through 3 suggest that this is the result of a copy which is triggered by your call to -copyAsNonEssential. Given that you got the download from the framework, it’s not clear why the priority would be bad. However, it does give you something to check for, that is, get the priority of download and see what it is.

Share and Enjoy

Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Background Assets The online Appstore crashed : EXC_BREAKPOINT
 
 
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