Add server_multithreaded parameter

[alexjfisher]

Puppet Server 6.8 has just been released with an experimental new
feature.

This release adds a new JRuby pool architecture that maintains a
single JRuby instance through which requests to Puppet Server are run
concurrently. In this mode, the server's memory footprint is
significantly lighter, because it no longer needs to run multiple JRuby
instances. Toggle this behavior by setting the
jruby-puppet.multithreaded to true.

This commit adds support for this new setting.

[ekohl]

Looking closer, it would be better to use the real_puppetserver_version variable as determined here:

puppet-puppet/manifests/server.pp

Lines 475 to 483 in 0de3202

	# For Puppetserver, certain configuration parameters are version specific. We
	# assume a particular version here.
	if $puppetserver_version {
	$real_puppetserver_version = $puppetserver_version
	} elsif versioncmp($::puppetversion, '6.0.0') >= 0 {
	$real_puppetserver_version = '6.0.0'
	} else {
	$real_puppetserver_version = '5.3.6'
	}

The reason is that the version number might be undef (default).

[alexjfisher]

I think this is already the case? (Although the module can be a bit confusing to follow). The template function is called from puppetserver.pp and uses $server_puppetserver_version. This defaults to $::puppet::server::real_puppetserver_version.

puppet-puppet/manifests/server/puppetserver.pp

Line 108 in 0de3202

$server_puppetserver_version = $::puppet::server::real_puppetserver_version,

[ekohl]

You're right on that part. However, maybe it's good to add another condition that if the puppetversion is at least 6.12.0 then the puppetserver version is 6.8.0?

[alexjfisher]

You're right on that part. However, maybe it's good to add another condition that if the puppetversion is at least 6.12.0 then the puppetserver version is 6.8.0?

That could very easily not be true though. The current code is conservative. If your puppet version is 6.X, then so is your puppetserver. Much more than that would probably be too great an assumption.

[ekohl]

yes, in general it's a complicated situation.