[jboss-jira] [JBoss JIRA] Commented: (JGRP-837) Add failure simulation capabilities to Simulator

Fri Oct 17 10:56:20 EDT 2008

    [ https://jira.jboss.org/jira/browse/JGRP-837?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12434244#action_12434244 ] 

Richard Achmatowicz commented on JGRP-837:
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Just for the record, I decided to start implementing this now as I was looking through NAKACK and I suspect there is a problem with REBROADCAST which I wanted to confirm.

My suspicion is that, because the code implementing the REBROADCAST callaback only tries a fixed number of times to get all messages in sync before it returns, a peer whose XMIT_RSP messages  were persistently dropped would not have its FIFO state updated correctly before REBROADCAST returns. This breaks the VS guarantee maintained by FLUSH, if my suspicions are correct.

So I needed to write a test case which could:
(i) take three peers and get each of them into a specific FIFO state (i.e. specific state of stabilized, received, and delivered messages)
(ii) initiate a REBROADCAST callback on one peer
(iii) cause another peer who needs to respond to XMIT_RSP messages to drop all of them persistently.

I believe that the functionality added to Simulator can be used to set up conditions (i) and (iii).

> Add failure simulation capabilities to Simulator 
> -------------------------------------------------
>
>                 Key: JGRP-837
>                 URL: https://jira.jboss.org/jira/browse/JGRP-837
>             Project: JGroups
>          Issue Type: Feature Request
>            Reporter: Richard Achmatowicz
>            Assignee: Richard Achmatowicz
>            Priority: Minor
>
> The Simulator can be used to test protocol layers in isolation. Multiple Simulator instances can be configured so that they model a multicast group.
> In its present state, messages are transported from one Simulator instance to another by the send_thread, which moves messages from send_queue to recv_queue in a reliable fashion.  Futhermore, all Simulators perform at the same speed. I'd like to use the Simulator to additionally simulate failures, in order to check the robustness of the protocols. In particular, i'd like to model:
> * dropped, reordered, corrupted messages
> * failed processors ('crash' failure)
> * network partitions
> * slow processes
> This JIRA issue will track progress on this and allow for discussion.

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