Hotswap

[Ulf Wiger]

On Thu, 3 Apr 2003, Vance Shipley wrote:

>Hot swap is useful for more than constant uptime production
>systems.  When you are doing development on a system
>involving more than a few modules/processes the startup
>time can be significant.  Just starting an erlang node
>takes a while.  I generally edit code in one window and
>then in another I am running an erlang shell on the system
>under test in which I run c(module) which compiles and
>loads the new module.  You then test, edit, test, etc.
>This iteration is really fast compared to a cold boot of
>the erlang node and starting the processes.

Oh, and this feature is a jaw dropper at Interops. I've
heard several accounts where people have brought
erlang-based systems to interops (Megaco, MPLS, etc.), and
have debugged and fixed interoperability problems in minutes
without restarting the system -- sometimes without even
dropping the session!

I also seem to recall occasions where the erlang guys have
helped their competitors debugging _their_ system simply by
being able to follow the communication so much better on the
erlang side. Finally, I've heard accounts of the erlang guys
implementing workarounds to other people's bugs simply
because it was so much easier to do it that way than to wait
for them to get a fix from their design teams.

/Uffe
-- 
Ulf Wiger, Senior Specialist,
   / / /   Architecture & Design of Carrier-Class Software
  / / /    Strategic Product & System Management
 / / /     Ericsson AB, Connectivity and Control Nodes