NSPOSIXErrorDomain Code=12 "Cannot allocate memory" in 3G network - iphone

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;
}