Random stalling

[Jim Lesurf]

I don't think the following is due to a flaw in gip. But it keeps happening
so I'd like to describe it and invite any comments regarding its cause or
what might be done.

In general I run a small program to do a set of gip fetches each morning,
timed to complete before the 9am 'deadline' when BT start clocking data
against out 'cap' value. The program simply issues a sequence of command
line fetches using gip. This lets me write a text file which lists the pids
that my program reads and then uses these to issue the fetch commands via
system() one by one.

Most mornings this works fine. But sometimes it doesn't. 

The most common symptom is that a command line fetch begins, but then halts
with the progress at  0.0%.  More rarely, it halts after the Commencing...

A ctrl-C generally simply causes the command to shut down the process it
had started and go on to the next fetch. This may or may not work.

A point to make here is that the behaviour seems 'random' in the sense that
often issuing the same command in the same with the same PID shortly
afterward duly works fine.

Occasionally when I ctrl-C the fetch it generates an 'error'. But again
these seem to vary 'randomly'. i.e. the same program fetch show  this on
one try but not on another, or may clean up with no error, or a different
one. In the bulk of cases, a failure simply cleans up without any reported
error.

I'm raising this now because I initially spent about 10 mins this morning
re-trying the same set of 5 PIDs and they kept failing. Then some worked.
Then some which had still refused worked. Only one persisted in stalling at
0.0%. By then 9am approached and I was doing other things anyway, so I
stopped for the day. My guess is that if I try to fetch that program later
today it will fetch OK.

My *guess* is that this is some analogue of 'leaves on the line' or 'the
wrong kind of snow' affecting my connections. I also sometimes get the
'busy' page from the iplayer using firefox at times. Again, I suspect the
problem is that somewhere along the pipework between me and the BBC
servers enough other traffic is involved to disrupt things. Thus leaving
gip waiting for a packet whist the server is waiting for a request because
something got lost.

If so, no idea if this is because I live north of Edinburgh, so in a
different world to the LBH machines, or if it is a local problem, or my
ISP.

Again, most mornings I get no problems at all. Sometimes I get one problem
try. This morning was a struggle. There's no pattern I've noticed.

Comments?

Jim

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