[jboss-jira] [JBoss JIRA] (JGRP-1973) FRAG2: message corruption when thread pools are disabled

[Bela Ban (JIRA)]

Bela Ban created JGRP-1973:
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             Summary: FRAG2: message corruption when thread pools are disabled
                 Key: JGRP-1973
                 URL: https://issues.jboss.org/browse/JGRP-1973
             Project: JGroups
          Issue Type: Bug
    Affects Versions: 3.6.6
            Reporter: Bela Ban
            Assignee: Bela Ban
             Fix For: 3.6.7


When disabling the thread pools (regular, OOB) and using {{UDP}}, fragments of a message get corrupted as a single buffer ({{UDP.receive_buf}}) is reused.

* If we send a message of 1000 bytes, and {{FRAG2.frag_size}} is set to 600, then {{FRAG2}} sends 2 fragments: f1 (offset=0, length=600) and f2 (offset=600, length=400).
* f1 is received and placed into {{receive_buf}}, then sent up the stack *without copying* as the {{DirectExecutor}} thread pool doesn't copy the data
* f1 is received by {{FRAG2}} and added to the fragments list at index 0. The buffer of the message points to {{receive_buf}}
* f2 is received and *overwrites* f1 in {{receive_buf}} !
* f2 is received by {{FRAG2}} and added to the fragments list at index 1. The buffer of the message points to {{receive_buf}}
* {{FRAG2}} now creates a new message whose buffer is {{receive_buf}}[0-600] and {{receive_buf}}[600-1000].
* The problem here is that {{receive_buf}} contains only f2, which overwrote f1, so the resulting message will be incorrect !

This probably affects {{FRAG}}, too.

Not too critical, as thread pools are enabled by default, and disabling them might even be removed in the future.

SOLUTION:



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