Thread: Pipes sometimes fail

Hello all,

I'm working on an application which basically does the following:

1. Create pipes for stdin/stdout/stderr
2. Fork

Then for the child:
1. Close unneeded side of the pipes, close 0, 1, 2, dup the pipes to stdin, stdout and stderr
2. Wait for a single-char message on stdin
3. Continue the program, sending data to stdout/stderr

Then for the parent:
1. Wait until we can read or write from one of the pipes (poll)
2. Do whatever we can do (all input is already available before this runs, so we close the input pipe on our end). If we can send output, first send a single character. (to stop waiting for a single char message in the child)

Now, most of the times it works fine. Sometimes, the output doesn't seem to work (that is, the child can't send on the stdout and stderr pipes). If I sleep for a little while in the child, however, it always works fine.

What could the problem be?


Thanks in advance.

Thank you for your answer.
Yes, I am closing stdin, stdout and stderr. It's quite common practice. At least, I've seen it done in many programs. And I have to do it in this program I'm working on, since it pipes input/output to another program. Similar to the standard pipe operator in Linux.
What I mean by it doesn't work... Well, it's painful to debug. I found out that it's actually just not sending data. I haven't been able to figure out the returned errno yet, but my guess is it's a broken pipe.

But there MUST be a cleaner way to fix such a thing. Yes, sleeping for a very short time is my current solution, and I have implemented it and it works. But I find it a disgusting hack..