[jboss-jira] [JBoss JIRA] (JGRP-1710) Messages get too large due to big headers (in large clusters)

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-1710?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12808551#comment-12808551 ] 

Bela Ban commented on JGRP-1710:
--------------------------------

As discussed on JGRP-1507: FRAG\{2\} cannot be moved over the transport as retransmission of large messages with 1 fragment missing would cause retransmission of the entire message (all fragments).

Therefore, the current strategy is to move large data from the header into the message's buffer and - if needed - add a second FRAG\{2\} directly over the transport. This second fragmentation protocol would typically not have to do any work, as fragmentation is done by the first fragmentation protocol. The only case where work would need to be done is when large data are added by a protocol, e.g. view and digest by {{INSTALL_MERGE_VIEW in GMS}}.

The advantage of moving large data into the body of a message is that FRAG2.down() can do a cheap {{Message.getLength()}}, compared to a more costly {{Message.size()}} by {{FRAG.down(){{.
                
> Messages get too large due to big headers (in large clusters)
> -------------------------------------------------------------
>
>                 Key: JGRP-1710
>                 URL: https://issues.jboss.org/browse/JGRP-1710
>             Project: JGroups
>          Issue Type: Bug
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>             Fix For: 3.4
>
>
> In some cases, messages get bigger than the max bundling size because of large headers:
> {panel}
> ERROR 17:33:08,096 | Timer-5,c0,172.29.189.9-svc9-ZM26S32728-59135 | [TP.java:1335] | (org) | 172.29.189.9-svc9-ZM26S32728-59135: failed sending message to 172.29.190.181-svc2-00832091-31665 (70850 bytes): java.lang.Exception: message size (70850) is greater than max bundling size (64000). Set the fragmentation/bundle size in FRAG and TP correctly, headers: GMS: GmsHeader[INSTALL_MERGE_VIEW]: view=MergeView::[172.29.190.174-svc6-00832251-874|27] (1479) ...
> {panel}
> In the case of INSTALL_MERGE_VIEW, we send the full view (*not* the DeltaView) and the digest in the header. With 1479 members (as shown the the example above), this increases the message size beyond the max bundling size.
> Possible SOLUTION
> * Place the header fields in the message's buffer instead
> * Move FRAG2 *under* GMS
> ** Investigate impact on flow control etc

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