NSPOSIXErrorDomain Code=12 “Cannot allocate memory

Question

I'm trying to send a file on FTP server in my iPhone application. Everything seems to be okay in WiFi and GSM:EDGE network, but in 3G network an error appears (not always, but very often):

Error Domain=NSPOSIXErrorDomain Code=12 "The operation couldn’t be completed. Cannot allocate memory"

Below the code where the error appears:

- (void)stream:(NSStream*)aStream handleEvent:(NSStreamEvent)eventCode {

    switch( eventCode ) {
        case NSStreamEventHasSpaceAvailable: {
            if( _readDataOffset == _readDataLimit ) {
                NSInteger readDataLen = [_readStream read:[_readData mutableBytes] maxLength:kReadDataLength];
                NSLog(@"readDataLen is %d",readDataLen);
                if( -1 == readDataLen ) {
                    _error = [[_readStream streamError] retain];
                    _keepRunning = NO;
                } else if( 0 == readDataLen ) {
                    _keepRunning = NO;
                } else {
                    _readDataOffset = 0;
                    _readDataLimit = readDataLen;
                }
            }

            if( _readDataOffset != _readDataLimit ) {
                NSOutputStream* writeStream = (NSOutputStream*)aStream;

                uint8_t *buffer = (void *)[_readData bytes];

          // vvvv and here  the value of writtenDataLen is often -1 (but only on 3G network)
                NSInteger writtenDataLen = [writeStream write:&buffer[_readDataOffset] maxLength:_readDataLimit - _readDataOffset]; 


                if( writtenDataLen > 0 ) {
                    _readDataOffset += writtenDataLen;
                    _writtenDataLen += writtenDataLen;
                    [self ftpPutDidWriteInternal];
                } else if( -1 == writtenDataLen ) {
                    _error = [[writeStream streamError] retain];
                    _keepRunning = NO;
                }
            }

        } break;
        case NSStreamEventErrorOccurred: {
            _error = [aStream.streamError retain];
            _keepRunning = NO;
        } break;
    }    
}

What can be important, the whole sending is done in separate thread which has it's own NSAutoreleasePool. Is there anyone who got the issue? Any suggestion? I would be appreciate.

UPDATE: I've just checked that popular iPhone application "FTP On The Go" has got the same (?) issue during sending a file in 3G network! There is no error handled, but the transfer stops.

UPDATE 2: I can't believe it, but it's true: SimpleFTPSample from Apple is also affected with the issue.

Answer 1

And here it is - the solution (or rather workaround):

you should set property of writeStream to false, to switch off default persistant connection

CFWriteStreamSetProperty( (CFWriteStreamRef)writeStreamRef, kCFStreamPropertyFTPAttemptPersistentConnection, kCFBooleanFalse ) ;

Answer 2

Have resolved this error with using operation for request (NSMutableUrlConnection) with @autorelease{} for main function

- (void)main
 NSURLConnection* connection;
    @autoreleasepool //urgently needed for 3G upload
    {

        self.currentRequest = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:@"test.php"]];
        [self.currentRequest setHTTPMethod:@"PUT"];

        [self.currentRequest setHTTPBody:self.data];//inpustStream doesn't work

        connection = [NSURLConnection connectionWithRequest:self.currentRequest delegate:self];
        [connection start];

    }//end autorelease pool

        do 
        {

            [[NSRunLoop currentRunLoop] runMode: NSDefaultRunLoopMode beforeDate: [NSDate distantFuture]];
            if ([self isCancelled])
            {
                connection          = nil;
                isFailed = YES;
                break;
            }
            self.status(statusUpdateMessage);
        } 
        while (!isFailed && !isCompleted);
        [timer invalidate];//test
        timer = nil;

//corresponding of status via blocks
        self.completed(!isFailed);
        self.status(isFailed ? errorMessage : @"Completed");
        if (isFailed)
        {
            self.failed(errorMessage != nil ? errorMessage : @"Undefined error");
        }

        self.data = nil;
        self.currentRequest = nil;

        connection = nil;

}