Child process unbuffered output is lost

[bguezzie]

Similar to issue #6595

When using unbuffered output on a child process (specifically "python -u my_child_script.py") and the 'data' event, my (parent) node process receives 'data' events for a portion of the data on the child's stdout, but drops the last several writes from the child process (which we do control, and we are even flushing stdout after each write just to make sure). For clarity, I am attaching a 'data' event listener immediately after the process is spawned, and I never remove a listener from the process.

Specifically, our child process outputs yaml documents over a period of time (status updates, essentially), and when the process exits not all of the yaml has been received by my 'data' listener prior to the 'close' event though I have confirmed that the data has indeed all been written and flushed.

No data exists in child.stdout for reading (this is after the child's 'close' event, and is expected behavior per the API), so it appears that the data is permanently missing.

[indutny]

Could you please provide a test case for this problem?

[bguezzie]

We actually resolved this in our code. False alarm, sorry.