[jira] [Created] (GEODE-8374) ViewAckTimeout Configuration

["Juan Ramos (Jira)" <ji...@apache.org>]

Juan Ramos created GEODE-8374:
---------------------------------

             Summary: ViewAckTimeout Configuration
                 Key: GEODE-8374
                 URL: https://issues.apache.org/jira/browse/GEODE-8374
             Project: Geode
          Issue Type: Bug
          Components: membership
            Reporter: Juan Ramos


We have the following within our docs (point 4 [here|https://geode.apache.org/docs/guide/112/managing/network_partitioning/how_network_partitioning_management_works.html]):

{noformat}
In the first phase, the membership coordinator sends out a view preparation message to all members and waits 12 seconds for a view preparation ack return message from each member. If the coordinator does not receive an ack message from a member within 12 seconds, the coordinator attempts to connect to the member’s failure-detection socket. If the coordinator cannot connect to the member’s failure-detection socket, the coordinator declares the member dead and starts the membership view protocol again from the beginning.
{noformat}

These 12 seconds refer to {{viewAckTimeout}} property within the {{GMSJoinLeave}} class, and it’s calculated as follows:
{code:title=GMSJoinLeave.java|borderStyle=solid}
    long ackCollectionTimeout = config.getMemberTimeout() * 2 * 12437 / 10000;
    if (ackCollectionTimeout < 1500) {
      ackCollectionTimeout = 1500;
    } else if (ackCollectionTimeout > 12437) {
      ackCollectionTimeout = 12437;
    }
    ackCollectionTimeout = Long
        .getLong(GeodeGlossary.GEMFIRE_PREFIX + "VIEW_ACK_TIMEOUT", ackCollectionTimeout)
        .longValue();
    this.viewAckTimeout = ackCollectionTimeout;
{code}

So, the actual value for the {{viewAckTimeout}} is {{member-timeout * 2}} seconds, but it can’t be lower than {{1.5}}, neither higher than {{12}}, unless the user configures the undocumented {{VIEW_ACK_TIMEOUT}} system property (for which I haven't found any tests nor anything related, meaning that _*it shouldn't be used at all as we don't know what the negative implications - if any - are*_).
We should either remove the internal check and allow the user to fully configure this property ({{member-timeout * 2}} by default) or add better documentation about this internal timeout and why it shouldn't be changed outside of the fixed interval.



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