Metadata expiry and computing a new expiration time.

[Rod Widdowson]

> Tomcat7 is using its default:
> 
>         JAVA_OPTS="-Djava.awt.headless=true -Xmx128M"
> 

That’s gotta hurt.

https://wiki.shibboleth.net/confluence/display/IDP30/ApacheTomcat8  says
"-Xmx512m - this is the maximum amount of memory that Tomcat may use, at
least 512M is recommended"

and the UK federation page (the UK federation was historically where memory
problems kick in) says:

http://www.ukfederation.org.uk/content/Documents/Setup2IdP "Tomcat's default
heapspace memory allocation is not likely to be sufficient for the IdP. At
least 1024MB is needed, perhaps more. Here is a description of the problem
and how to resolve it."

> > I'm a little confused, sorry - I'm not getting any memory or heap
related
> errors, the only thing in the logs is that it has successfully retrieved
and
> unmarshalled the federation metadata, and updated the expiry time, when
> it
> hasn't. Is that heap related?   If so I can experiment, 

There is anecdotal evidence (no more) that the http client does not function
well in memory short environments.  All it would take would be some code to
accidently swallow the exception silently and hang instead.  It could even
be the native code below it running into problems.  

> I just don't know where
> this request has come from.

Suffice to say that more than one user has seen these problems, and then
seen them go away when they added memory.  This could of course just be
hiding the problem.

If you want you could turn up logging or the apache http client and see
whether that said anything.

/Rod