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authorjhh <jorge.hernandez-herrero@att.com>2020-06-12 17:01:24 -0500
committerjhh <jorge.hernandez-herrero@att.com>2020-06-15 11:56:21 -0500
commit108dd8ff62cbdfbbe1ba3589afe43582105ea275 (patch)
tree6007bd025b40e1aca92c3cfe1b0672f7645c917d /docs/drools/feature_pooling.rst
parent11de40286f2a91edc9755f6ea9e621006452527b (diff)
drools documentation redo
Issue-ID: POLICY-2622 Signed-off-by: jhh <jorge.hernandez-herrero@att.com> Change-Id: I568c041f972c76b595964ee3de731c1cde304d8f Signed-off-by: jhh <jorge.hernandez-herrero@att.com>
Diffstat (limited to 'docs/drools/feature_pooling.rst')
-rw-r--r--docs/drools/feature_pooling.rst17
1 files changed, 9 insertions, 8 deletions
diff --git a/docs/drools/feature_pooling.rst b/docs/drools/feature_pooling.rst
index f7d3579d..ba950a3d 100644
--- a/docs/drools/feature_pooling.rst
+++ b/docs/drools/feature_pooling.rst
@@ -2,13 +2,12 @@
.. This work is licensed under a Creative Commons Attribution 4.0 International License.
.. http://creativecommons.org/licenses/by/4.0
+ .. _feature-pool:
+
****************
Feature: Pooling
****************
-Summary
-^^^^^^^
-
The Pooling feature provides the ability to load-balance work across a “pool” of active-active Drools-PDP hosts. This particular implementation uses a DMaaP topic for communication between the hosts within the pool.
The pool is adjusted automatically, with no manual intervention when:
@@ -16,7 +15,7 @@ The pool is adjusted automatically, with no manual intervention when:
* a host goes offline, whether gracefully or due to a failure in the host or in the network
Assumptions and Limitations
-^^^^^^^^^^^^^^^^^^^^^^^^^^^
+===========================
* Session persistence is not required
* Data may be lost when processing is moved from one host to another
* The entire pool may shut down if the inter-host DMaaP topic becomes inaccessible
@@ -25,7 +24,7 @@ Assumptions and Limitations
Key Points
-^^^^^^^^^^
+==========
* Requests are received on a common DMaaP topic
- DMaaP distributes the requests randomly to the hosts
- The request topic should have at least as many partitions as there are hosts
@@ -38,7 +37,8 @@ Key Points
* Precludes feature(s): session-persistence, active-standby, state-management
Example Scenario
-^^^^^^^^^^^^^^^^
+================
+
1. Incoming DMaaP message is received on a topic — all hosts are listening, but only one random host receives the message
2. Decode message to determine “request ID” key (message-specific operation)
3. Hash request ID to determine the bucket number
@@ -51,7 +51,8 @@ Example Scenario
.. image:: poolingPdps.png
Bucket Reassignment
-^^^^^^^^^^^^^^^^^^^
+===================
+
* When a host goes up or down, buckets are rebalanced
* Attempts to maintain an even distribution
* Leaves buckets with their current owner, where possible
@@ -62,7 +63,7 @@ Bucket Reassignment
.. image:: poolingBuckets.png
Usage
-^^^^^
+=====
For pooling to be enabled, the distributed-locking feature must be also be enabled.