iPhone application crashes with Mprotect failed error (MonoTouch)

Question

I have a problem with my iPhone application developed with MonoTouch.
I am developing an application that contacts a WCF Service, and when the WCF Service answer back, I update an UITableView with the returned data, when this is done it sends a new WCF async call, and when it answer back it updates the table again and so on.

The problem is that when it has done this in a variable amount of time, it crashes with an Mprotect failed error 12. This only happens when the application is running directly on the phone and not in the simulator.

I have tried to out comment where the update of the table happens, and making a Thread.Sleep(1000) before sending the next Async request to the WCF Service, but still the same error, but can run longer with out failing.

I contact the WCF Service through the "proxy" files, generated by SlSvcUtil.exe /noConfig http://mydomain/myservice.svc

My question is that can this error be avoid in a way or maybe with a workaround? Is it my fault, or is it a bug? It is actually because I shall use the application in my final school project, so it could be nice if I could fix it.

I post the console output, and a part from the crash report, but if you need more info please tell me, and I will post it. I am not a pro to use Mono or the MonoTouch environment it is my first time, so detailed responses would be nice.

Console output:

Mon Dec 27 20:37:17 tests-iPhone UIKitApplication:dk.test.iphone[0x1c3c][625] <Notice>: Mprotect failed at 0xa09a000 (length 1052672) with errno 12

Mon Dec 27 20:37:17 tests-iPhone UIKitApplication:dk.test.iphone[0x1c3c][625] <Notice>: Stacktrace:

Mon Dec 27 20:37:17 tests-iPhone UIKitApplication:dk.test.iphone[0x1c3c][625] <Notice>:   at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication.UIApplicationMain (int,string[],intptr,intptr) <0xffffffff>

Mon Dec 27 20:37:17 tests-iPhone UIKitApplication:dk.test.iphone[0x1c3c][625] <Notice>:   at MonoTouch.UIKit.UIApplication.Main (string[],string,string) <0x000e0>

Mon Dec 27 20:37:17 tests-iPhone UIKitApplication:dk.test.iphone[0x1c3c][625] <Notice>:   at MonoTouch.UIKit.UIApplication.Main (string[]) <0x00023>

Mon Dec 27 20:37:17 tests-iPhone UIKitApplication:dk.test.iphone[0x1c3c][625] <Notice>:   at iPhoneStdView.Application.Main (string[]) <0x0001b>

Mon Dec 27 20:37:17 tests-iPhone UIKitApplication:dk.test.iphone[0x1c3c][625] <Notice>:   at (wrapper runtime-invoke) object.runtime_invoke_dynamic (intptr,intptr,intptr,intptr) <0x000c3>

Mon Dec 27 20:37:17 tests-iPhone UIKitApplication:dk.test.iphone[0x1c3c][625] <Notice>: Native stacktrace:

Mon Dec 27 20:37:18 tests-iPhone ReportCrash[635] <Notice>: Formulating crash report for process iPhoneNoNavigation[625]

Mon Dec 27 20:37:18 tests-iPhone com.apple.launchd[1] (UIKitApplication:dk.test.iphone[0x1c3c][625]) <Warning>: (UIKitApplication:dk.test.iphone[0x1c3c]) Job appears to have crashed: Abort trap

Mon Dec 27 20:37:18 tests-iPhone SpringBoard[27] <Warning>: Application 'iPhoneStdView' exited abnormally with signal 6: Abort trap

Crash report:

Thread 0 Crashed:
0   dyld                            0x2fe08110 0x2fe00000 + 33040
1   libSystem.B.dylib               0x3020259e 0x301ff000 + 13726
2   libSystem.B.dylib               0x302531da 0x301ff000 + 344538
3   iPhoneNoNavigation              0x0051975c 0x1000 + 5343068
4   iPhoneNoNavigation              0x00538080 0x1000 + 5468288
5   libSystem.B.dylib               0x302765cc 0x301ff000 + 488908
6   libSystem.B.dylib               0x30201d64 0x301ff000 + 11620
7   CoreFoundation                  0x3081fc38 0x307f8000 + 162872
8   CoreFoundation                  0x3081f4c2 0x307f8000 + 160962
9   CoreFoundation                  0x3081f270 0x307f8000 + 160368
10  CoreFoundation                  0x3081f178 0x307f8000 + 160120
11  GraphicsServices                0x31e445ec 0x31e40000 + 17900
12  GraphicsServices                0x31e44698 0x31e40000 + 18072
13  UIKit                           0x31e5111c 0x31e4d000 + 16668
14  UIKit                           0x31e4f128 0x31e4d000 + 8488
15  iPhoneNoNavigation              0x0006e754 0x1000 + 448340

Thread 0 crashed with ARM Thread State:
    r0: 0x35f4d17c    r1: 0x302765a9      r2: 0x35989b04      r3: 0x0000000e
    r4: 0x2fe29e78    r5: 0x07d17490      r6: 0x302765d3      r7: 0x2fffe24c
    r8: 0x00000000    r9: 0x3598762c     r10: 0x0000000d     r11: 0x07d17470
    ip: 0x3598762c    sp: 0x2fffe240      lr: 0x3e08dc60      pc: 0x2fe08110
  cpsr: 0x20000030

Lasky

Answer 1

Error 12 is ENOMEM, you've exhausted all the memory available on the iphone.

Melia

Are you sure ? I have Overidden the method ReceiveMemoryWarning in AppDelegate Class: public override void ReceiveMemoryWarning (UIApplication application) { Log.Error("Memory warning", "memory"); } But I never get this error.. – Lasky

Okay, can I do something to avoid this problem? Or should i just change my program code, to be more memory light. I just cant understand that my program can be so memory heavy. – Lasky

You can be more pro-active with your large objects, and remember to call Dispose() on them, instead of waiting for the GC to kick-in. Small objects you can let the GC handle, but large beasts like images, or memorystreams or other caches you want to clear as soon as possible. – Neuter

We too are having this same problem. We have a simple app that does http requests, and after a while it fails at this mprotect call. From what I read of mprotect, it isn't doing any actual memory allocation. Plus the iPad 2 gives us a memory log, which shows tons of memory still available. This is a major issue for us, and we may have to send our whole app to Novell to play with (but it takes time to fail of course). – Prolongate