Ios WebTryThreadLock线程崩溃0xbbadbeef

我们从客户那里看到的最常见的崩溃是来自_WebTryThreadLock的异常（0xbbadbeef总是在WebThread中，thread#2）。通常，崩溃包含与代码无关的其他线程（包括主线程）。我们不能在内部复制它。我们在代码中查找了可能使用其他线程的UIWebView的情况，但没有找到任何结果。我们总是在释放webview的委托之前将其取消设置

我们可以从各种设备以及我所能看到的任何iOS版本（在当前的5.x范围内）中看到这一点。根据日志，它似乎主要发生在应用程序从后台恢复时

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0xbbadbeef
Crashed Thread:  2

Thread 0 name:  Dispatch queue: com.apple.root.default-priority
Thread 0:
0   libsystem_kernel.dylib              0x328e31d4 madvise + 8
1   ImageIO                             0x3306c550 CGImageRead_willNeed + 52
2   ImageIO                             0x331bcd98 __copyImageBlockSetPNG_block_invoke_0 + 476
3   libdispatch.dylib                   0x35d03a68 _dispatch_apply_serial + 16
4   libdispatch.dylib                   0x35cf44b4 _dispatch_client_callout + 20
5   libdispatch.dylib                   0x35d02886 _dispatch_sync_f_invoke + 22
6   ImageIO                             0x331bb446 copyImageBlockSetPNG + 2102
7   ImageIO                             0x3306b53e ImageProviderCopyImageBlockSetCallback + 510
8   CoreGraphics                        0x33fc59d6 CGImageProviderCopyImageBlockSetWithOptions + 158
9   QuartzCore                          0x3a4f474c CA::Render::create_image(CGImage*, CGColorSpace*, unsigned int) + 668
10  QuartzCore                          0x3a4f433a CA::Render::copy_image(CGImage*, CGColorSpace*, unsigned int, double) + 254
11  QuartzCore                          0x3a4f4226 CA::Render::prepare_image(CGImage*, CGColorSpace*, unsigned int, double) + 14
12  QuartzCore                          0x3a4e2af0 CA::Layer::prepare_commit(CA::Transaction*) + 416
13  QuartzCore                          0x3a4e221e CA::Context::commit_transaction(CA::Transaction*) + 242
14  QuartzCore                          0x3a4e2024 CA::Transaction::commit() + 312
15  UIKit                               0x3af260b6 -[UIApplication _reportAppLaunchFinished] + 38
[...]

Thread 2 name:  WebThread
Thread 2 Crashed:
0   WebCore                             0x379a99ca _WebTryThreadLock(bool) + 298
1   WebCore                             0x379a988a WebRunLoopLock(__CFRunLoopObserver*, unsigned long, void*) + 42
2   CoreFoundation                      0x336da6ca __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 18
3   CoreFoundation                      0x336d89bc __CFRunLoopDoObservers + 272
4   CoreFoundation                      0x336d8c8c __CFRunLoopRun + 604
5   CoreFoundation                      0x3364beb8 CFRunLoopRunSpecific + 352
6   CoreFoundation                      0x3364bd44 CFRunLoopRunInMode + 100
7   WebCore                             0x379a7a40 RunWebThread(void*) + 440
8   libsystem_c.dylib                   0x35d3e30e _pthread_start + 306
9   libsystem_c.dylib                   0x35d3e1d4 thread_start + 4

[...]

Thread 5 name:  JavaScriptCore::BlockFree
Thread 5:
0   libsystem_kernel.dylib              0x328f308c __psynch_cvwait + 24
1   libsystem_c.dylib                   0x35d36d2a _pthread_cond_wait + 642
2   libsystem_c.dylib                   0x35d36aa0 pthread_cond_timedwait + 40
3   JavaScriptCore                      0x39b67c70 WTF::ThreadCondition::timedWait(WTF::Mutex&, double) + 104
4   JavaScriptCore                      0x39c79552 JSC::BlockAllocator::blockFreeingThreadMain() + 78
5   JavaScriptCore                      0x39c8bfa8 WTF::wtfThreadEntryPoint(void*) + 12
6   libsystem_c.dylib                   0x35d3e30e _pthread_start + 306
7   libsystem_c.dylib                   0x35d3e1d4 thread_start + 4

Thread 6 name:  WebCore: CFNetwork Loader
Thread 6:
0   libsystem_kernel.dylib              0x328e2eb4 mach_msg_trap + 20
1   libsystem_kernel.dylib              0x328e3048 mach_msg + 36
2   CoreFoundation                      0x336da040 __CFRunLoopServiceMachPort + 124
3   CoreFoundation                      0x336d8d9e __CFRunLoopRun + 878
4   CoreFoundation                      0x3364beb8 CFRunLoopRunSpecific + 352
5   CoreFoundation                      0x3364bd44 CFRunLoopRunInMode + 100
6   WebCore                             0x37a42f6a WebCore::runLoaderThread(void*) + 138
7   JavaScriptCore                      0x39c8bfa8 WTF::wtfThreadEntryPoint(void*) + 12
8   libsystem_c.dylib                   0x35d3e30e _pthread_start + 306
9   libsystem_c.dylib                   0x35d3e1d4 thread_start + 4

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根据我的项目目前的经验，这是一个WebKit因GWT应用程序内存泄漏而内存不足的示例，我们正在尝试修复该应用程序

根据我的项目目前的经验，这是一个WebKit因GWT应用程序内存泄漏而内存不足的示例，我们正在尝试修复该应用程序