[jboss-jira] [JBoss JIRA] (JGRP-1674) STOP_FLUSH race condition

[Dennis Reed (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1674?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12797410#comment-12797410 ] 

Dennis Reed commented on JGRP-1674:
-----------------------------------

Proposed fix details:

STOP_FLUSH is sent in two cases:
1.  onResume called with a list of participants.
    STOP_FLUSH is sent to each individual participant, so no need to verify that the STOP_FLUSH is valid in this case.
    Did not change this use case.
2.  onResume called with "null" participants
    STOP_FLUSH is multicast, which may be seen by members that were not in the START_FLUSH.
    Added current flushMembers to the STOP_FLUSH message.

up(STOP_FLUSH) modified to block the STOP_FLUSH only if the newly added flushParticipants list is not null, and flushParticipants does not include this node, and this node did not sent the STOP_FLUSH.

                
> STOP_FLUSH race condition
> -------------------------
>
>                 Key: JGRP-1674
>                 URL: https://issues.jboss.org/browse/JGRP-1674
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 2.6.21
>            Reporter: Dennis Reed
>            Assignee: Bela Ban
>             Fix For: 3.4
>
>
> There is a race condition in STOP_FLUSH when a node joins the cluster.
> JOINER sends JOIN_REQ to MASTER
> MASTER does a flush on the existing members (does NOT include JOINER)
> MASTER sends JOIN_RSP
> MASTER sends STOP_FLUSH
> JOINER receives JOIN_RSP
> JOINER fetches state, sends START_FLUSH
> JOINER receives STOP_FLUSH from MASTER (does not apply, since JOINER was not part of the original FLUSH)
> onStopFlush never verifies that the current node was part of the FLUSH, and therefore is valid for the current node.
> This STOP_FLUSH corrupts JOINER's FLUSH by resetting all the member variables (and probably unblocking as well).

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