[JBoss JIRA] Created: (JGRP-1153) Shared transport badly broken
by Björn Kautler (JIRA)
Shared transport badly broken
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Key: JGRP-1153
URL: https://jira.jboss.org/jira/browse/JGRP-1153
Project: JGroups
Issue Type: Bug
Affects Versions: 2.7
Environment: EHCache 1.7.2
ehcache-jgroupsreplication 1.3
JGroups 2.7.0.GA
Reporter: Björn Kautler
Assignee: Bela Ban
I tried to use JGroups with a shared transport (while using only one JChannel, the one EHCache uses for replication). At ProtocolStack.java:719 the TP.ProtocolAdapter is added to the protocol stack when a shared transport is used. This leads to problems after shunning. When the JChannel.CloserThread tries in line 2018 to reopen the JChannel, the Protocol Stack is recreated. But now the TP$ProtocolAdapter is part of the protocol stack and thus of the config string created from the protocol stack at JChannel:327. As the ProtocolAdapter does not have a default constructor, the whole thing explodes at Configurator:732 where the newInstance() call of course fails while the ProtocolAdapter probably shouldn't be in the protocol stack anyway at this point in time. I guess it would be added a second time at ProtocolStack.java:719 then. Also after disabling the shared transport it seems that the problem I was able to reproduce halfway reliably through restarting both instances simultaneously doesn't arise again without shared transport.
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16 years, 1 month
[JBoss JIRA] Created: (JGRP-822) NAKACK: concurrent delivery of messages from the same sender
by Bela Ban (JIRA)
NAKACK: concurrent delivery of messages from the same sender
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Key: JGRP-822
URL: https://jira.jboss.org/jira/browse/JGRP-822
Project: JGroups
Issue Type: Feature Request
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 2.x
JGroups delivers messages from different senders concurrently. However, it delivers messages from the same sender sequentially. Sometimes, we can deliver messages from the same sender concurrently too, if the app tells us it is okay. For example:
- Node N was 3 HTTP sessions: A, B and C
- Clients update those sessions concurrently
- As a result, N sends the following messages: A1, B1, A2, C1, C2, C3, B2, A3
- As NAKACK assigns sequence numbers (seqnos) based on JGroups instances, all messages from N will have to be
delivered in the same order in which they were sent, e.g. (-> means followed by):
A1 -> B1 -> A2 -> C1 -> C2 -> C3 -> B2 -> A3
- This means that, for example, the first update to C (C1) has to wait until A1, B1 and A2 have been delivered
- This is not optimal, as updates for A, B and C are completely independent, and can be delivered in parallel
- So a better delivery would be ('||' means concurrent delivery):
A1 -> A2 -> A3 || B1 -> B2 || C1 -> C2 -> C3
- A3 needs to be delivered after A2 which needs to be delivered after A1. However, all updates for A can be delivered
concurrently with messages for B or C.
- OOB doesn't help: here all messages are delivered concurrently, but there is also no ordering within A, B or C !
SOLUTION: the sender adds a 'scope' token to a Message, e.g. the jsessionid (A, B or C). JGroups maintains NakReceiverWindows per *scope*, not per sender. The sender's address is the default token, so in the absence of a scope token, JGroups of course maintains NakReceiverWindows per sender. (NakReceiverWindows are used to keep track of seqnos).
In the above example, if the scopes sent with *each message* are A, B and C, then we'd have 3 NakReceiverWindows:
N::A, N::B, N::C.
Each window would start with seqno 1, so updates for A, B and C are delivered concurrently with respect to each other, but sequentially within the scope.
Issues:
- This is an API change, and should probably be propagated up to the building blocks, such as RpcDispatcher.
- A scope needs to be associated with an address A (of a JGroups instance): when A leaves or crashes, all associated scopes and their NakReceiverWindows needs to be released, too
- Should this be done for UNICAST too ?
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16 years, 1 month
[JBoss JIRA] Created: (JBAS-6293) Chapter 11 example missing from JBoss AS 5.0.0.GA
by Bruce Link (JIRA)
Chapter 11 example missing from JBoss AS 5.0.0.GA
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Key: JBAS-6293
URL: https://jira.jboss.org/jira/browse/JBAS-6293
Project: JBoss Application Server
Issue Type: Bug
Security Level: Public (Everyone can see)
Components: Docs/Installation and Getting Started Guide
Affects Versions: JBossAS-5.0.0.GA
Environment: Not applicable
Reporter: Bruce Link
Assignee: Samson Kittoli
The installation and getting started guide discusses a jsfejb3 example.
"11.4.1. Building The Application
Let's look at building the example application and then explore the configuration files in detail.
In Chapter 10, Sample Applications , we looked at the directory structure of the jsfejb3 sample application. "
The example directory does not exist in the referenced %JBOSS_HOME%/docs/examples directory.
Chapter 10 does not look at the directory structure of this or any other sample application.
Reference to actual application directory and code/configuration and build files needs to be provided
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16 years, 1 month