Stdout buffer in gfortran

[ShrirajHegde]

@urbanjost

The conversion of large amounts of data to ASCII text via formatted writes can be expensive, so even before you write to any device I/O that you are going to throw away can be expensive, so never generate large amounts of data thinking it is free to write it to /dev/null.

Yes, that seems logical. But what is the efficient way to enable and disable the debug print statements? Preprocessor directives?

@urbanjost

/dev/null is not only not the same as not writing the output, but can slow you down more than if you wrote the lines to a file.

But I still don’t understand how writing to /dev/null can be slower than an actual file. Is it because of the absence of output buffering for non-regular files? Or are you saying in general irrespective of gfortran.