On a project I worked on we used a bit of a heavy handed method. Our system
was rather distributed, where servers processed messages off of durable
queues. So we took a simplistic approach: Exceptions that bubbled all the
way up to the top level of the application caused a hard exit of the JVM.
That's right, we crashed the entire JVM (and restarted it) every time we
had a un-handled exception.
Over time we refined this approach to whitelist some exceptions. So a
clojure read exception wouldn't crash the JVM it would only re-try the
message processing. Since our application used durable queues, and because
we had about 20 machines consuming from each queue, a single JVM restarting
here and there wasn't bad. And we gained the assurance that an error
wouldn't leave the JVM in a bad state.
Won't work in all (or most) situations, but it worked pretty well for us.
Timothy
On Mon, Apr 20, 2015 at 2:05 PM, Luc Préfontaine
lprefonta...@softaddicts.ca wrote:
1) no
2) no
3) yes at all cost
4) both, exceptions are logged with context (current bindings, etc)
5) undecided, under close examination however
6) never have to restart, we check what cause the error and correct it
externally if required
most errors are reported immediately, may depend on the failed process
being critical
or not.
Up times above 250 days, restarts only required when upgrading stuff.
Luc P.
I'm curious, how are people in the Clojure community currently dealing
with
exceptions? I have a diverse set of questions on this topic.
1.) How many have adopted an Erlang die fast and restart strategy?
2.) How many use something like Supervisor to spin up new JVMs? If not
Supervisor, then what?
3.) How many try to catch all exceptions and therefore try to keep the
app
running under all circumstances?
4.) If you use something like Kafka to log events, do you use the same
log
to track exceptions, or do you track exceptions separately?
5.) How many use a catch/restart library such as Ribol?
6.) In general, how bad do you expect things to be before you allow the
software to die, have Nagios send a pager alert to your sysadmin, drag
them
out of bed at 3 AM, and have a human examine the issue and restart things
manually?
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zero–they had no way to indicate successful termination of their C
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