iOS Amazon S3 SDK: message sent to deallocated instance - ios

Question

I'm getting the following error:
*** -[S3PutObjectOperation_Internal respondsToSelector:]: message sent to deallocated instance 0x43c18fd0
I don't understand the stack trace from Zombies inspector very well, I'm not sure this is telling me anything I can fix:
# Address Category Event Type RefCt Timestamp Size Responsible Library Responsible Caller
0 0xc071f60 S3PutObjectOperation_Internal Malloc 1 00:14.903.021 48 MyApp -[S3TransferManager upload:]
1 0xc071f60 S3PutObjectOperation_Internal Retain 2 00:14.903.032 0 Foundation ____addOperations_block_invoke_0
2 0xc071f60 S3PutObjectOperation_Internal Release 1 00:14.903.036 0 MyApp -[S3TransferManager upload:]
3 0xc071f60 S3PutObjectOperation_Internal Retain 2 00:14.904.154 0 libsystem_sim_blocks.dylib _Block_object_assign
4 0xc071f60 S3PutObjectOperation_Internal Retain 3 00:14.904.163 0 libsystem_sim_blocks.dylib _Block_object_assign
5 0xc071f60 S3PutObjectOperation_Internal Release 2 00:14.904.164 0 Foundation __destroy_helper_block_474
6 0xc071f60 S3PutObjectOperation_Internal Retain 3 00:14.906.549 0 MyApp -[S3PutObjectOperation_Internal start]
7 0xc071f60 S3PutObjectOperation_Internal Release 2 00:14.906.554 0 MyApp -[S3PutObjectOperation_Internal start]
8 0xc071f60 S3PutObjectOperation_Internal Release 1 00:14.907.624 0 MyApp __destroy_helper_block_
9 0xc071f60 S3PutObjectOperation_Internal Retain 2 00:15.243.299 0 MyApp -[S3PutObjectOperation_Internal finish]
10 0xc071f60 S3PutObjectOperation_Internal Retain 3 00:15.243.302 0 MyApp -[S3PutObjectOperation_Internal finish]
11 0xc071f60 S3PutObjectOperation_Internal Release 2 00:15.243.307 0 MyApp -[S3PutObjectOperation_Internal finish]
12 0xc071f60 S3PutObjectOperation_Internal Release 1 00:15.243.330 0 MyApp -[S3PutObjectOperation_Internal finish]
13 0xc071f60 S3PutObjectOperation_Internal Release 0 00:15.244.420 0 Foundation __release_object_op
14 0xc071f60 S3PutObjectOperation_Internal Zombie -1 00:15.386.107 0 MyApp -[S3Response connection:didSendBodyData:totalBytesWritten:totalBytesExpectedToWrite:]
This error happens when the application is uploading photos. The Photo object uses and implements the following methods:
-(void)request:(AmazonServiceRequest *)request didSendData:(NSInteger)bytesWritten totalBytesWritten:(NSInteger)totalBytesWritten totalBytesExpectedToWrite:(NSInteger)totalBytesExpectedToWrite
{
NSLog(#"didSendData called: %d - %d / %d", bytesWritten, totalBytesWritten, totalBytesExpectedToWrite);
self.transferProgress += bytesWritten;
float p = (float) self.transferProgress / self.uploadSize;
self.uploadProgress = [NSNumber numberWithFloat:p];
}
-(void)request:(AmazonServiceRequest *)request didCompleteWithResponse:(AmazonServiceResponse *)response
{
NSLog(#"didCompleteWithResponse called.");
}
-(void)request:(AmazonServiceRequest *)request didFailWithError:(NSError *)error
{
NSLog(#"didFailWithError called: %#", error);
}
As far as I know this is the only point in the app in which the S3 request is talking to any other objects/instances. Any idea what is causing this error?

Answer 1

I think this is a bug in the AWS SDK. I'm not sure where exactly the bug is but it's triggered by request retries if the response was a service exception (and possibly only in conjunction with S3TransferManager).
I didn't want to disable all retries, so I fixed this by forcing no retries for service exceptions. You can do this by using a subclass of AmazonS3Client where you override one method like this:
- (BOOL)shouldRetry:(AmazonServiceResponse *)response exception:(NSException *)exception
{
// There is some kind of bug that is triggered on request retries when S3 requests
// return an explicit service exception (e.g., auth token expired). In these cases
// we force no retry to avoid the bug.
NSException *exceptionHolder = response.exception;
if(exceptionHolder == nil)
{
exceptionHolder = exception;
}
if([exceptionHolder isKindOfClass:[AmazonServiceException class]])
{
return NO;
}
return [super shouldRetry:response exception:exception];
}