[jboss-jira] [JBoss JIRA] (JGRP-1486) Merge failure when dead instances remain in view

Merge failure when dead instances remain in view ------------------------------------------------ Key: JGRP-1486 URL: https://issues.jboss.org/browse/JGRP-1486 Project: JGroups Issue Type: Bug Affects Versions: 3.0.10 Reporter: David Hotham Assignee: Bela Ban I've hit this testing my JGRP-1485 fix, but I think it's a logically independent issue. So, I've reached a point where: - A, B and C all have view {C,A,B} - D has view {B', D', D, A', C}, in which B', D' and A' are all dead instances As in JGRP-1485, an optimal fix would surely be to allow D to recover all by itself, but it's not clear to me how to do that. However, my expectation was that a merge should sort things out; and I think that if it did then that ought to be good enough. But what's actually happening is this: - C becomes merge leader - determines that merge participants are C, D', D, A' - sends MERGE_REQ to those members - the MERGE_REQ to D' reaches D (and that to A' reaches A) - D sends a positive response for the MERGE_REQ that was meant for it, but after 2.5 seconds also sends a negative response to the MERGE_REQ meant for D'. (I think that the negative response is because it can't fetch the digest from D') - likewise A sends a negative response to the MERGE_REQ meant for A' So what C sees is: - good responses from C and D, followed by merge_rejected responses from A and D - so it removes A' and D' from the merge (it didn't get responses from them) - then it removes D from the merge (because the most recent response from D said merge_rejected) - so it is left only with itself, and comes up with a consolidated view that is identical to its original view in short: the merge doesn't do anything useful after all. I think that the key here is the confusion between D and D'. Possibly the fix is as simple as: ignore MERGE_REQs where the destination address on the message is not the local address. I'll try this out and, if it looks good, submit a pull request.