Adding ERLANG VM tuning parameters

This fix will add ERLANG VM tuning parameters with increased
default settings to support larger installations.
Following overrides have been added:
  rabbitmq_async_threads defaults to 128 (from 32)
  rabbitmq_process_limit defaults to 1048576 (from 256k)

Closes-Bug: #1549940
DocImpact

Change-Id: Ia0fab288db8aa287e667dfc843f02d7ec318a816

defaults/main.yml

@@ -70,3 +70,7 @@ rabbitmq_ssl_self_signed_subject: "/C=US/ST=Texas/L=San Antonio/O=IT/CN={{ conta
 #rabbitmq_user_ssl_cert: <path to cert on ansible deployment host>
 #rabbitmq_user_ssl_key: <path to cert on ansible deployment host>
 #rabbitmq_user_ssl_ca_cert: <path to cert on ansible deployment host>
+
+# RabbitMQ erlang VM parameters
+rabbitmq_async_threads: 128
+rabbitmq_process_limit: 1048576

doc/source/index.rst

@@ -18,3 +18,14 @@ Basic Role Example
       vars:
         rabbitmq_cookie_token: secrete
         container_address: "{{ ansible_ssh_host }}"
+
+
+Role overrides
+^^^^^^^^^^^^^^
+
+rabbitmq_async_threads
+  This override defaults to 128 threads for IO operations inside the erlang VM
+
+rabbitmq_process_limit
+  This override defaults to 1048576 for number of concurrent processes inside the erlang VM
+  Each network connection and file handle does need its own process inside erlang

tasks/rabbitmq_post_install.yml

@@ -40,6 +40,7 @@
   with_items:
     - { src: "rabbitmq.config.j2", dest: "/etc/rabbitmq/rabbitmq.config" }
     - { src: "rabbitmq-server.j2", dest: "/etc/default/rabbitmq-server" }
+    - { src: "rabbitmq-env.j2", dest: "/etc/rabbitmq/rabbitmq-env.conf" }
   tags:
     - rabbitmq-config
 

templates/rabbitmq-env.j2

@@ -0,0 +1,5 @@
+# {{ ansible_managed }}
+
+# Set ERLANG VM parameters
+RABBITMQ_IO_THREAD_POOL_SIZE={{ rabbitmq_async_threads }}
+RABBITMQ_SERVER_ERL_ARGS="+P {{ rabbitmq_process_limit }}"