[Pipet Devel] Re: Booting and shutting down piper

J.W. Bizzaro jeff at bioinformatics.org
Tue Dec 19 09:23:49 EST 2000

Jean-Marc Valin wrote:
> Same for me, I just got back from one week at the beach in Martinique, which is
> why you didn't hear from me (wow, no e-mail reading for a full week!). I didn't
> quite follow the whole discussion (not very familiar with this part of Piper),
> can anyone summerize for me what's going on/tell me where I should get involved
> in this discussion?

I'll try to explain.......

Jarl has been looking to implement a system-wide (covering all the layers of
Piper) shutdown and recovery mechanism.

The approach Jarl and I have settled on for the time being (it's not the best,
but it will work for the pilot), is to put the PID's of each Piper process in
the user's $HOME/piper_info/pids directory, then from UIL->DL->BL->PL (top to
bottom) send a "kill <PID>" (not "kill -9") to the next lower layer.  This
will allow each layer to begin its own shutdown, and that should be that
(unless a layer can't die).

The other benefit of storing the PID's is to determine what is running, or
what has crashed, should things be re-started.

I was a bit confused about what Jarl wanted me to do in the UIL and DL,
because I knew that Brad had already developed a shutdown/crash recovery
mechanism.  Brad explained his mechanism in a recent message and suggested
that Jarl use the same approach for the other layers (all layers).

My question at this point is for Jarl: Do you understand what Brad is
proposing for the whole system (that which is implemented in the UIL and DL)? 
What do you think?

Jarl also brought up a problem with sending network information (an XML
"document") from the UIL to the PL.  He has been getting errors from the PL. 
Jarl, can you send copies of those errors to this list so that Brad and
Jean-Marc can see them?

J.W. Bizzaro                                           jeff at bioinformatics.org
Director, Bioinformatics.org: The Open Lab     http://bioinformatics.org/~jeff
"All those scientists--they're all alike!  They say they're working for us,
but what they really want is to rule the world!" 
  -- Angry Villager, Young Frankenstein

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