Can't read large file (2.5GB) with QFile

[ChrisW67]

QIODevice::readLine() and QIODevice::readAll() return QByteArrays not QStrings. The QString is being constructed using the conversion constructor, which uses QString::fromAscii(). Depending on the current codec if the first byte of the file is not valid, e.g. a UTF-8 byte-order-mark, then you may well end up with an empty string.

So, what does you file actually contain, and is it valid characters only?


...
On second thoughts, even if your byte array slurped the entire file into memory, conversion to 16-bit characters in a QString will double the size and blow the 4GB limit on 32-bit architectures.

[DanH]

Yeah, I'm guessing he's out of storage, one way or another.

[enricong]

I am on a 64-bit RHEL5 system

The file is all text.

Upon further examination, readLine() does work. the first line in the file is blank, if I read the second line, I could see the text. Although this seems to get stuck once the program hits 1.0gb of resident memory usage.

readAll() just seems to give up and not even try. I looked into it more closely and it looks like it fails to resize the QByteArray to 2.5gb. I would have expected an error but I guess that makes sense.
I've got 12GB ram on this system.

[SixDegrees]

What is the output of 'ulimit -a'? And what context does your code occur in - main() or within a function?