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Diffstat (limited to 'docs/drools/feature_pooling.rst')
| -rw-r--r-- | docs/drools/feature_pooling.rst | 17 |
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. |