无法追踪[NSData getBytes:length:]崩溃

Question

我EXC_BAD_ACCESS在Foundation的-[NSData(NSData) getBytes:length:]方法中遇到了一个奇怪的崩溃.它经常发生,但我无法从堆栈跟踪中获得任何有意义的信息.getBytes:length:除了开源库(一进SDWebImage一出SocketRocket)之外,我的代码内部没有调用,但它们似乎并没有导致崩溃.

唯一的提示是崩溃发生在com.apple.CFNetwork.addPersistCacheToStorageDaemon线程内部,但我不知道它是什么.有人可以帮忙吗？

来自Crashlytics的Stacktrace:

Thread : Crashed: com.apple.CFNetwork.addPersistCacheToStorageDaemon
0  libsystem_platform.dylib       0x3044a208 _platform_memmove$VARIANT$CortexA9 + 160
1  Foundation                     0x22df9167 -[NSData(NSData) getBytes:length:] + 118
2  Foundation                     0x22df9167 -[NSData(NSData) getBytes:length:] + 118
3  Foundation                     0x22e21a1b -[NSData(NSData) replacementObjectForCoder:] + 134
4  Foundation                     0x22dc2aff -[NSXPCEncoder _replaceObject:] + 90
5  Foundation                     0x22e240dd -[NSXPCEncoder _encodeArrayOfObjects:forKey:] + 192
6  Foundation                     0x22e212ff -[NSDictionary(NSDictionary) encodeWithCoder:] + 922
7  Foundation                     0x22dc32c9 -[NSXPCEncoder _encodeObject:] + 604
8  Foundation                     0x22dc379d encodeInvocationArguments + 460
9  Foundation                     0x22dc3455 -[NSXPCEncoder encodeInvocation:] + 360
10 Foundation                     0x22dc32c9 -[NSXPCEncoder _encodeObject:] + 604
11 Foundation                     0x22dc2335 -[NSXPCConnection _sendInvocation:proxyNumber:remoteInterface:withErrorHandler:timeout:userInfo:] + 1860
12 Foundation                     0x22dd2823 -[NSXPCConnection _sendInvocation:proxyNumber:remoteInterface:withErrorHandler:] + 58
13 Foundation                     0x22dd27db -[_NSXPCDistantObjectWithError forwardInvocation:] + 114
14 CoreFoundation                 0x2217e831 ___forwarding___ + 352
15 CoreFoundation                 0x220afb88 _CF_forwarding_prep_0 + 24
16 CFNetwork                      0x21c52ac9 -[NSURLStorage_CacheClient addCachedResponseWithDictionary:key:] + 120
17 CFNetwork                      0x21c21e29 ___ZN12__CFURLCache23CreateAndStoreCacheNodeEP16__CFURLCacheNodePK20_CFCachedURLResponsePK10__CFStringPK13_CFURLRequestPKvbRb_block_invoke + 1576
18 libdispatch.dylib              0x302cf423 _dispatch_call_block_and_release + 10
19 libdispatch.dylib              0x302d95d9 _dispatch_queue_drain$VARIANT$mp + 948
20 libdispatch.dylib              0x302d90a9 _dispatch_queue_invoke$VARIANT$mp + 84
21 libdispatch.dylib              0x302db0d3 _dispatch_root_queue_drain + 330
22 libdispatch.dylib              0x302dc1fb _dispatch_worker_thread3 + 106
23 libsystem_pthread.dylib        0x3044ce25 _pthread_wqthread + 668

而另一个(不常发生):

Thread : Crashed: com.apple.CFNetwork.addPersistCacheToStorageDaemon
0  libsystem_platform.dylib       0x000000019344d300 _platform_memmove + 176
1  Foundation                     0x0000000182dfce18 -[NSData(NSData) getBytes:length:] + 172
2  Foundation                     0x0000000182dfce18 -[NSData(NSData) getBytes:length:] + 172
3  Foundation                     0x0000000182e2ae3c -[NSData(NSData) replacementObjectForCoder:] + 160
4  Foundation                     0x0000000182dbd320 -[NSXPCEncoder _replaceObject:] + 120
5  Foundation                     0x0000000182e2dac8 -[NSXPCEncoder _encodeArrayOfObjects:forKey:] + 256
6  Foundation                     0x0000000182e2a544 -[NSDictionary(NSDictionary) encodeWithCoder:] + 1016
7  Foundation                     0x0000000182dbdd10 -[NSXPCEncoder _encodeObject:] + 716
8  Foundation                     0x0000000182dbe2e8 encodeInvocationArguments + 508
9  Foundation                     0x0000000182dbdee4 -[NSXPCEncoder encodeInvocation:] + 412
10 Foundation                     0x0000000182dbdd10 -[NSXPCEncoder _encodeObject:] + 716
11 Foundation                     0x0000000182dbcb0c -[NSXPCConnection _sendInvocation:proxyNumber:remoteInterface:withErrorHandler:timeout:userInfo:] + 2196
12 CoreFoundation                 0x0000000181fde230 ___forwarding___ + 440
13 CoreFoundation                 0x0000000181ee2b6c _CF_forwarding_prep_0 + 92
14 CFNetwork                      0x000000018199c908 ___ZN12__CFURLCache23CreateAndStoreCacheNodeEP16__CFURLCacheNodePK20_CFCachedURLResponsePK10__CFStringPK13_CFURLRequestPKvbRb_block_invoke + 1976
15 libdispatch.dylib              0x00000001932793ac _dispatch_call_block_and_release + 24
16 libdispatch.dylib              0x000000019327936c _dispatch_client_callout + 16
17 libdispatch.dylib              0x00000001932834c0 _dispatch_queue_drain + 1216
18 libdispatch.dylib              0x000000019327c474 _dispatch_queue_invoke + 132
19 libdispatch.dylib              0x0000000193285224 _dispatch_root_queue_drain + 664
20 libdispatch.dylib              0x000000019328675c _dispatch_worker_thread3 + 108
21 libsystem_pthread.dylib        0x00000001934552e4 _pthread_wqthread + 816

Answer 1

我的猜测是你有

• 一些（对于 setter Path 来说 __unsafe_unretained这是不可避免的[NSInvocation setArgument:atIndex:]）
• 或者像这样的问题
• 或者（更有可能）在 （因为我在堆栈中看到连接/超时）期间出现死锁performBlockAndWait

一些相关建议：

1) NSManagedObject、NSManagedObjectContext和NSPersistentStoreCoordinator（考虑到崩溃addPersistCacheToStorageDaemon）不是线程安全的：

• 如果您用于向您的（更多信息请参见此处和此处）或 嵌套 MOCperformBlockAndWait发送消息，请考虑这一点。NSManagedObjectContext

2)CFNetwork是一个较低级别的类，由以下内容包装NSURLConnection：

• 所以不使用NSURL？避免addObserver:self forKeyPath(KVO) NSURL 会话的属性？