| Subject: | Deep recursion in Net::Appliance::Session 1.36 |
| Date: | Mon, 18 Jan 2010 15:45:07 -0000 |
| To: | bug-Net-Appliance-Session [...] rt.cpan.org |
| From: | "Campbell, Steve" <Steve.Campbell [...] virginmedia.co.uk> |
Hi,
I've come across a replicatable error message as follows:
"Deep recursion on subroutine "Net::Appliance::Session::cmd" at
/opt/perllib/Net/Appliance/Session/Engine.pm line 37. "
I get this when running a command which generates a huge amount of
output, after disabling paging.
What is happening is that the command is timing out, and the eval in
Net::Telnet::waitfor() is calling close().
The close calls enable_paging().
Enable_paging() calls cmd() with the paging command.
Cmd() calls waitfor()
This fails as the device hasn't finished the original command yet. The
eval then calls close() and we go into a death spiral.
The fix is add the accessor close_called, and add the following lines to
close() -
# Ensure we don't go into a loop if the clean up commands fail.
return if $self->close_called;
$self->close_called(1);
The original command still fails, but at least we now get a meaningful
time out message!
Next things I'm looking are to fix waitfor() such that
* Pattern matches are only done on the last line of output, to avoid
performance costs going exponential with large command outputs. Hmm.
This got reported and rejected in 2003.
* Reset the timeout clock whenever it receives more data
* Allow waitfor to squirt out the data as it gets it, instead of having
to wait until the command ends.
Of course, these aren't your concern, but you might be interested...
Thanks,
Steve
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