Update os_workers to have other options

Adding additional options for os_workers.rb:

        os_workers_small
        os_workers_large

os_workers will provide response times close to what
$::processorcount had (with two sockets machines).

os_workers_small will be the existing calculation.

os_workers_large can be used where services are distributed across
multiple machines and high worker count is not a concern.

Closes-bug: #1650424

Change-Id: I5dce760044d49ef9e3c88736c73cc267fd039ae7

lib/facter/os_workers.rb

@@ -11,10 +11,40 @@
 # This fact can be overloaded by an external fact from /etc/factor/facts.d if
 # a user would like to provide their own default value.
 #
-Facter.add(:os_workers) do
+Facter.add(:os_workers_small) do
   has_weight 100
   setcode do
     processors = Facter.value('processorcount')
     [ [ (processors.to_i / 4), 2 ].max, 8 ].min
   end
 end
+
+#
+# The value above for os_workers performs 3x worse in many cases compared to
+# the prevuous default of $::processorcount.
+#
+# Based on performance data [1], the following calculation is within 1-2%.
+#
+# The value for os_workers is max between '(<# processors> / 2)' and '2' with
+# a cap of 12.
+#
+# [1] http://elk.browbeatproject.org:80/goto/a23307fd511e314b975dedca6f65425d
+#
+Facter.add(:os_workers) do
+  has_weight 100
+  setcode do
+    processors = Facter.value('processorcount')
+    [ [ (processors.to_i / 2), 2 ].max, 12 ].min
+  end
+end
+
+#
+# For cases where services are not co-located together (ie monolithic).
+#
+Facter.add(:os_workers_large) do
+  has_weight 100
+  setcode do
+    processors = Facter.value('processorcount')
+    [ (processors.to_i / 2) ]
+  end
+end

releasenotes/notes/os_workers-fact-0ce731f0536c2792.yaml

@@ -0,0 +1,12 @@
+---
+features:
+  - Moved existing $::os_workers to $::os_workers_small
+  - Updated $::os_workers to have a value between '2' and '12'.
+    The value of this fact is the larger value between '2'
+    and the number of processors divided by '2' but will not
+    exceed '12'.
+  - Created fact $::os_workers_large to have a value of number
+    of processors divided by '2'
+fixes:
+  - bug 1650424 The current calculation for os_workers negatively
+    impacts api response times