xamarin.ios - 实例化 NSObject 导致内存不足崩溃

Question

运行以下代码时，应用程序崩溃(约 30 秒后)并显示以下堆栈跟踪。我觉得这很奇怪，因为我希望垃圾收集器清理这段内存。我们的应用程序具有类似的模式，并会因类似的堆栈跟踪而崩溃。

注释掉实例化 NSObject 成员的行可以使应用程序运行而不会崩溃。注释掉实例化字节数组的行会使应用运行时间更长，但它仍然会崩溃。

Instruments 报告应用程序的 Live Bytes 非常稳定，并且检测会导致应用程序运行更长时间而不会崩溃，但它仍然会崩溃(大约 10 分钟后)。恒定的 Live Bytes 让我觉得垃圾收集器正在工作。

代码:

using System.Threading;
using MonoTouch.Foundation;
using MonoTouch.UIKit;

namespace MyExample
{
    public class Application
    {
        static void Main (string[] args)
        {
            UIApplication.Main(args);
        }
    }

    public partial class AppDelegate : UIApplicationDelegate
    {
        public override bool FinishedLaunching (UIApplication app, NSDictionary options)
        {
            Thread testThread = new Thread(BreakMe);
            testThread.Start();

            window.MakeKeyAndVisible();
            return true;
        }

        private void BreakMe()
        {
            while(true)
            {
                using (var arPool = new NSAutoreleasePool())
                {
                    MyGarbage garbage = new MyGarbage();
                }
            }
        }

        private class MyGarbage
        {
            byte[] _Foo = new byte[100000];
            NSObject _Bar = new NSObject();
        }
    }
}

应用输出:

Mprotect failed at 0x493c000 (length 4096) with errno 12
Stacktrace:

  at (wrapper managed-to-native) System.Array.CreateInstanceImpl (System.Type,int[],int[]) <0xffffffff>
  at System.Array.CreateInstance (System.Type,int[]) <0x000bc>
  at System.Array.CreateInstance (System.Type,int) <0x00057>
  at System.MonoCustomAttrs.GetCustomAttributes (System.Reflection.ICustomAttributeProvider,System.Type,bool) <0x000db>
  at System.MonoCustomAttrs.GetCustomAttribute (System.Reflection.ICustomAttributeProvider,System.Type,bool) <0x00033>
  at System.Attribute.GetCustomAttribute (System.Reflection.MemberInfo,System.Type,bool) <0x0003f>
  at MonoTouch.ObjCRuntime.Class.GetHandle (System.Type) <0x00037>
  at MonoTouch.Foundation.NSObject.AllocIfNeeded () <0x00063>
  at MonoTouch.Foundation.NSObject..ctor (MonoTouch.Foundation.NSObjectFlag) <0x00027>
  at MonoTouch.Foundation.NSAutoreleasePool..ctor () <0x00037>
  at MyExample.AppDelegate.BreakMe () [0x00000] in Main.cs:30
  at (wrapper runtime-invoke) object.runtime_invoke_dynamic (intptr,intptr,intptr,intptr) <0x000cb>

Native stacktrace:

    0   MyExample                       0x002db308 mono_handle_native_sigsegv + 404
    1   MyExample                       0x002fa5dc sigabrt_signal_handler + 148
    2   libsystem_c.dylib                   0x369c972f _sigtramp + 42
    3   libsystem_c.dylib                   0x369be3bb pthread_kill + 58
    4   libsystem_c.dylib                   0x369b6bff abort + 78
    5   MyExample                       0x0041e484 GC_remap + 200
    6   MyExample                       0x00411ee4 GC_allochblk_nth + 1536
    7   MyExample                       0x00411894 GC_allochblk + 96
    8   MyExample                       0x0041d94c GC_new_hblk + 116
    9   MyExample                       0x00413c3c GC_allocobj + 188
    10  MyExample                       0x0041859c GC_generic_malloc_inner + 352
    11  MyExample                       0x004187ac GC_generic_malloc + 132
    12  MyExample                       0x00418c60 GC_malloc + 208
    13  MyExample                       0x003a67dc mono_object_allocate + 64
    14  MyExample                       0x003a7240 mono_array_new_full + 828
    15  MyExample                       0x00341324 ves_icall_System_Array_CreateInstanceImpl + 896
    16  MyExample                       0x0012cf3c (wrapper managed-to-native) System.Array:CreateInstanceImpl (System.Type,int[],int[]) + 80
    17  MyExample                       0x0012d23c System.Array:CreateInstance (System.Type,int) + 88
    18  MyExample                       0x0018b70c System.MonoCustomAttrs:GetCustomAttributes (System.Reflection.ICustomAttributeProvider,System.Type,bool) + 220
    19  MyExample                       0x0018b560 System.MonoCustomAttrs:GetCustomAttribute (System.Reflection.ICustomAttributeProvider,System.Type,bool) + 52
    20  MyExample                       0x00131fd0 System.Attribute:GetCustomAttribute (System.Reflection.MemberInfo,System.Type,bool) + 64
    21  MyExample                       0x000795ec MonoTouch.ObjCRuntime.Class:GetHandle (System.Type) + 56
    22  MyExample                       0x00077e60 MonoTouch.Foundation.NSObject:AllocIfNeeded () + 100
    23  MyExample                       0x0007779c MonoTouch.Foundation.NSObject:.ctor (MonoTouch.Foundation.NSObjectFlag) + 40
    24  MyExample                       0x00074d10 MonoTouch.Foundation.NSAutoreleasePool:.ctor () + 56
    25  MyExample                       0x00002c34 MyExample.AppDelegate:BreakMe () + 164
    26  MyExample                       0x001f3e3c (wrapper runtime-invoke) object:runtime_invoke_dynamic (intptr,intptr,intptr,intptr) + 204
    27  MyExample                       0x002c4658 mono_jit_runtime_invoke + 3032
    28  MyExample                       0x003a34a8 mono_runtime_invoke + 140
    29  MyExample                       0x003a48f0 mono_runtime_delegate_invoke + 136
    30  MyExample                       0x003cb31c start_wrapper + 752
    31  MyExample                       0x003f09a0 thread_start_routine + 240
    32  MyExample                       0x0041f9ac GC_start_routine + 132
    33  libsystem_c.dylib                   0x369be311 _pthread_start + 248
    34  libsystem_c.dylib                   0x369bfbbc start_wqthread + 0

Answer 1

真正的答案是，怀疑，问题已在 Why is our MonoTouch app breaking in the garbage collector? It is not out of memory 中解决。这是一个内存管理器问题。堆栈跟踪对我来说非常熟悉。