stdout printing out of order?

[cpjust]

I don't understand how this is possible, but here it is.
I added some debug statements to each function in this file that just tells me when a function gets called.
In main(), right after some variables are defined, I have a DTRACE call that should print "In main()". However, when I run the program, "In main()" isn't printed first. What actually gets printed first is coming from a function that is called about 30-40 lines below my DTRACE statement.

I even added fflush( stdout ); to the end of my DTRACE() function just to see if that was the problem, but no luck.

This program really hates me...

[matsp]

Huh?
That doesn't make any sense at all. Are you sure that your printouts in themselves are correct and not cached/buffered someplace?

And I suppose your system is single-threaded, and not using multiple threads, right?

--
Mats

[MacGyver]

Is this a multithreaded program? Or one that spawns any type of process or subprocess, etc. etc..?

[brewbuck]

Are you sure DTRACE is printing to stdout, not stderr? If it was stderr, then your fflush(stdout) isn't doing anything.

Other than that, I don't know, unless you can post code.

[cpjust]

Hmm... This could be the problem, although I still don't understand why.

The program takes a command line argument -o filename and prints all the output to that file. I've been running it with -o /dev/stdout > filename

I think most of the program uses fprintf() or fputs() for its output (which in my case is using /dev/stdout), but my DTRACE() function just does plain old printf().

Is there some strange timing difference between opening /dev/stdout and writing to it vs. doing printf()?

[matsp]

If you open two different files to standard out, there's no prediction of whcih one "gets there first". Use the same FILE for both - e.g. change "stdout" to your output, or debug using fprintf(somefile, ...).

Mixing and matching won't be reliable in ordering, even if it's eventually reaching the same device.

--
Mats

[cpjust]

Thanks.
I just changed my DTRACE() function to fprintf() to the same FILE* and it looks like it's printing properly now.

[brewbuck]

Is there some strange timing difference between opening /dev/stdout and writing to it vs. doing printf()?

They each get their own FILE handle so they each get their own buffer. /dev/stdout is not very portable, anyway. On my system, it's a link to /proc/self/fd/1. And in the past, it wasn't a real device at all, but a "simulated device" created by bash -- you could only redirect to it, not open it as a file.

Maybe change your program so that if the "-o filename" option is not given, the output defaults to go to stdout. Most programs work that way.