diff --git a/mod_cluster/WFLY-10769_Integrate_mod_cluster_ramp-up_mechanism_when_starting_new_nodes.adoc b/mod_cluster/WFLY-10769_Integrate_mod_cluster_ramp-up_mechanism_when_starting_new_nodes.adoc new file mode 100644 index 000000000..f4c7e6d2d --- /dev/null +++ b/mod_cluster/WFLY-10769_Integrate_mod_cluster_ramp-up_mechanism_when_starting_new_nodes.adoc @@ -0,0 +1,72 @@ += WFLY-10769 Integrate mod_cluster ramp-up mechanism when starting new nodes +:author: Radoslav Husar +:email: rhusar@redhat.com +:toc: left +:icons: font +:keywords: clustering,undertow,mod_cluster +:idprefix: +:idseparator: - + +== Overview + +Newly joined nodes can become overloaded, since they initially report 0% load. +This has been a problem since inception of the project. +The problem is that the initial load stays in effect for performing load-balancing decisions until a new stat interval kicks in. +This effect is mitigated by load decay over time, but for the time a new node joins in, it can get overloaded upon startup. + +== Issue Metadata + +=== Issue + +* https://issues.jboss.org/browse/WFLY-10769[WFLY-10769] WFLY-6803 Integrate mod_cluster ramp-up mechanism when starting new nodes +* https://issues.jboss.org/browse/EAP7-1087[EAP7-1087] Integrate mod_cluster ramp-up mechanism when starting new nodes + +=== Related Issues + +* https://issues.jboss.org/browse/MODCLUSTER-449[MODCLUSTER-449] Implement ramp-up when starting new nodes +* https://issues.jboss.org/browse/WFLY-10440[WFLY-10440] Upgrade mod_cluster to 1.4.0.Final + +This feature is supported since mod_cluster version 1.4.0.Final and was part of the original upgrade PR, +but was pushed back by QE. + +=== Dev Contacts + +* mailto:rhusar@redhat.com[Radoslav Husar] + +=== QE Contacts + +* mailto:jkasik@redhat.com[Jan Kašík] + +=== Affected Projects or Components + +* WildFly/EAP +* mod_cluster +* Undertow + +=== Other Interested Projects + +* JWS + +== Requirements + +=== Hard Requirements + +* Nodes are registered with the configured load to gradually ramp them up. +* The default configuration is that the node is fully loaded (`initial-load="0"`) + +=== Nice-to-Have Requirements + +N/A + +=== Non-Requirements + +N/A + +== Test Plan + +QE has already pretested the feature. + +== Community Documentation + +The upstream documentation for this is submitted with the implementation PR. +Ideally, general documentation for the mod_cluster subsystem will be updated in the near future.