On Mon, 17 Mar 2008, Peter Edwards wrote:
In Chart::Graph::Gnuplot latest it looks like line 768 is in _exec_gnuplot()
which calls system() to run gnuplot.
There are known problems getting the exit status back from a spawned process
under Catalyst.
I hit this a while ago. I didn't manage to track it down quickly so I found
a workaround using IPC::Run. That might work for you if you use the
pseudo-ttys option.
Cat-devs, any pointers as to what in Catalyst is interfering with process
spawning and I/O redirection?
This has more to do with the kind of server you are running under than
with the Catalyst itself. More specifically, it has to do with how the
servers use the I/O, and yes, they do interfere. Most of them do.
The only combination I can use successfully is Apache/mod_perl. I run
gnuplot and r with IPC::Run3. Fastcgi and the Catalyst dev server screw up
STDIN (I believe they reopen and select() on it, but I am not sure). I
have studied all available server implementations in detail, but I can't
recall the details -- please forgive my vagueness. I was convinced that
there is nothing a person with my level of competence could do to fix
that.
So, I ended up running all my stuff under mod_perl (which I don't need
otherwise), and I have to restart the server every time I change my code,
which it quite a PITA, but I am grateful that there is at least one way to
make things work.
But I would also like a competent answer to this question: what can be
done to make the "normal" Catalyst code interact with unix processes on
all 3 channels? I mean, all 3: if a process spews something on stderr,
I'd like to capture that, consider how severe the message is (unless it
tells me in the status code) and possibly throw an exception and
ultimately forward the message to the browser.
I know I will be rebuked by the people thinking along the lines of
"cross-platform compatibility". Spare me. I will still want to run
gnuplot and a thousand other things, and talk to them through the unix
I/O, because that's all they afford me to do.
Thanks,
--Gene
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