BLOCKING and STDOUT/STDERR

[George C. Demetros]

Hi.

We have a Perl routine that prints messages to STDOUT and STDERR. It's possible
that the calling function may have redirected STDOUT/STDERR to FIFO files, and
the Perl routine is unaware of this. It appears that if the FIFO files are not
being read and that the files approach the 32K limit in size, that some sort of
blocking occurs in the Perl routine.

Is there some way of determining, within the Perl routine, when we hit this
limit and/or when blocking occurs so we can gracefully die? Again, the Perl
routine is unaware whether the calling function has redirected STDOUT/STDERR.

Thanks in advance!

George

 

[Ben Morrow]

We have a Perl routine that prints messages to STDOUT and STDERR. It's possible
that the calling function may have redirected STDOUT/STDERR to FIFO files, and
the Perl routine is unaware of this. It appears that if the FIFO files are not
being read and that the files approach the 32K limit in size, that some sort of
blocking occurs in the Perl routine.

Is there some way of determining, within the Perl routine, when we hit this
limit and/or when blocking occurs so we can gracefully die? Again, the Perl
routine is unaware whether the calling function has redirected STDOUT/STDERR.

The way to deal with this is to use non-blocking IO, which will fail
if the data cannot be written due to a full buffer. See
IO::Handle::blocking.

Ben