10:03 a.m.
Bela Ban created JGRP-1509:
------------------------------
Summary: GMS: low leave_timeout may cause incorrect view installation
Key: JGRP-1509
URL: https://issues.jboss.org/browse/JGRP-1509
Project: JGroups
Issue Type: Bug
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 3.0.15, 3.2
- {A}
- B joins, then C, the view is A2={A,B,C}
- *No* messages are sent
- GMS.leave_timeout=100
- NAKACK2.xmit_interval=1000
- A leaves gracefully (JChannel.disconnect())
- A multicasts B3={B,C}, the seqno is #3
- B discarded A#2 (view {A,B,C}), as it was not yet server
- B now asks A for retransmission of #2 before it can deliver #3 (the new view)
(- The retransmission kicks in ca. every 1 sec)
- However, A is gone, so C will loop asking A to retransmit #3 and will therefore never
install view B2 !
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11:13 a.m.
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Bela Ban updated JGRP-1509:
---------------------------
Attachment: tmp.xml
tmp.xml reproduces the issue. If GMS.leave_timeout is increased to 2000, the error
doesn't occur
GMS: low leave_timeout may cause incorrect view installation
------------------------------------------------------------
Key: JGRP-1509
URL: https://issues.jboss.org/browse/JGRP-1509
Project: JGroups
Issue Type: Bug
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 3.0.15, 3.2
Attachments: tmp.xml
- {A}
- B joins, then C, the view is A2={A,B,C}
- *No* messages are sent
- GMS.leave_timeout=100
- NAKACK2.xmit_interval=1000
- A leaves gracefully (JChannel.disconnect())
- A multicasts B3={B,C}, the seqno is #3
- B discarded A#2 (view {A,B,C}), as it was not yet server
- B now asks A for retransmission of #2 before it can deliver #3 (the new view)
(- The retransmission kicks in ca. every 1 sec)
- However, A is gone, so C will loop asking A to retransmit #3 and will therefore never
install view B2 !
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11:13 a.m.
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Bela Ban commented on JGRP-1509:
--------------------------------
Also, if we add a merge protocol (MERGE2 or MERGE3) to tmp.xml, A does get the new view
{B,C} after some time.
However, we should not rely on this and find a solution which works regardless of whether
a merge protocol is in the config, or leave_timeout is greater than the retransmit
interval of NAKACK(2).
GMS: low leave_timeout may cause incorrect view installation
------------------------------------------------------------
Key: JGRP-1509
URL: https://issues.jboss.org/browse/JGRP-1509
Project: JGroups
Issue Type: Bug
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 3.0.15, 3.2
Attachments: tmp.xml
- {A}
- B joins, then C, the view is A2={A,B,C}
- *No* messages are sent
- GMS.leave_timeout=100
- NAKACK2.xmit_interval=1000
- A leaves gracefully (JChannel.disconnect())
- A multicasts B3={B,C}, the seqno is #3
- B discarded A#2 (view {A,B,C}), as it was not yet server
- B now asks A for retransmission of #2 before it can deliver #3 (the new view)
(- The retransmission kicks in ca. every 1 sec)
- However, A is gone, so C will loop asking A to retransmit #3 and will therefore never
install view B2 !
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12:06 p.m.
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Bela Ban commented on JGRP-1509:
--------------------------------
Solution: if we're the coordinator, wait max(leave_timeout,
view_ack_collection_timeout) ms. Note that view_ack_collection_timeout should be higher
than xmit_interval in NAKACK(2) !
GMS: low leave_timeout may cause incorrect view installation
------------------------------------------------------------
Key: JGRP-1509
URL: https://issues.jboss.org/browse/JGRP-1509
Project: JGroups
Issue Type: Bug
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 3.0.15, 3.2
Attachments: tmp.xml
- {A}
- B joins, then C, the view is A2={A,B,C}
- *No* messages are sent
- GMS.leave_timeout=100
- NAKACK2.xmit_interval=1000
- A leaves gracefully (JChannel.disconnect())
- A multicasts B3={B,C}, the seqno is #3
- B discarded A#2 (view {A,B,C}), as it was not yet server
- B now asks A for retransmission of #2 before it can deliver #3 (the new view)
(- The retransmission kicks in ca. every 1 sec)
- However, A is gone, so C will loop asking A to retransmit #3 and will therefore never
install view B2 !
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12:08 p.m.
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Bela Ban commented on JGRP-1509:
--------------------------------
Actually, I correctr myself: a merge protocol should always be in the config, so even if
the final view from A is not received by all members, the merge protocol will eventually
merge the deviating views into a consolidated MergeView.
GMS: low leave_timeout may cause incorrect view installation
------------------------------------------------------------
Key: JGRP-1509
URL: https://issues.jboss.org/browse/JGRP-1509
Project: JGroups
Issue Type: Bug
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 3.0.15, 3.2
Attachments: tmp.xml
- {A}
- B joins, then C, the view is A2={A,B,C}
- *No* messages are sent
- GMS.leave_timeout=100
- NAKACK2.xmit_interval=1000
- A leaves gracefully (JChannel.disconnect())
- A multicasts B3={B,C}, the seqno is #3
- B discarded A#2 (view {A,B,C}), as it was not yet server
- B now asks A for retransmission of #2 before it can deliver #3 (the new view)
(- The retransmission kicks in ca. every 1 sec)
- However, A is gone, so C will loop asking A to retransmit #3 and will therefore never
install view B2 !
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12:08 p.m.
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Bela Ban resolved JGRP-1509.
----------------------------
Resolution: Done
GMS: low leave_timeout may cause incorrect view installation
------------------------------------------------------------
Key: JGRP-1509
URL: https://issues.jboss.org/browse/JGRP-1509
Project: JGroups
Issue Type: Bug
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 3.0.15, 3.2
Attachments: tmp.xml
- {A}
- B joins, then C, the view is A2={A,B,C}
- *No* messages are sent
- GMS.leave_timeout=100
- NAKACK2.xmit_interval=1000
- A leaves gracefully (JChannel.disconnect())
- A multicasts B3={B,C}, the seqno is #3
- B discarded A#2 (view {A,B,C}), as it was not yet server
- B now asks A for retransmission of #2 before it can deliver #3 (the new view)
(- The retransmission kicks in ca. every 1 sec)
- However, A is gone, so C will loop asking A to retransmit #3 and will therefore never
install view B2 !
--
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3:51 p.m.
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Bela Ban reopened JGRP-1509:
----------------------------
Another solution is to queue N number of messages received before we become a server
(is_server=true), then replay them. Thus we'd have no need for retransmissions
GMS: low leave_timeout may cause incorrect view installation
------------------------------------------------------------
Key: JGRP-1509
URL: https://issues.jboss.org/browse/JGRP-1509
Project: JGroups
Issue Type: Bug
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 3.0.15, 3.2
Attachments: tmp.xml
- {A}
- B joins, then C, the view is A2={A,B,C}
- *No* messages are sent
- GMS.leave_timeout=100
- NAKACK2.xmit_interval=1000
- A leaves gracefully (JChannel.disconnect())
- A multicasts B3={B,C}, the seqno is #3
- B discarded A#2 (view {A,B,C}), as it was not yet server
- B now asks A for retransmission of #2 before it can deliver #3 (the new view)
(- The retransmission kicks in ca. every 1 sec)
- However, A is gone, so C will loop asking A to retransmit #3 and will therefore never
install view B2 !
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5 p.m.
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Bela Ban commented on JGRP-1509:
--------------------------------
I went for the queueing solution. This has the advantage that we don't need to send a
retransmit request for seqno+1 to the coordinator, which is moot anyway if the coord
multicasts other messages besides the new view.
GMS: low leave_timeout may cause incorrect view installation
------------------------------------------------------------
Key: JGRP-1509
URL: https://issues.jboss.org/browse/JGRP-1509
Project: JGroups
Issue Type: Bug
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 3.0.15, 3.2
Attachments: tmp.xml
- {A}
- B joins, then C, the view is A2={A,B,C}
- *No* messages are sent
- GMS.leave_timeout=100
- NAKACK2.xmit_interval=1000
- A leaves gracefully (JChannel.disconnect())
- A multicasts B3={B,C}, the seqno is #3
- B discarded A#2 (view {A,B,C}), as it was not yet server
- B now asks A for retransmission of #2 before it can deliver #3 (the new view)
(- The retransmission kicks in ca. every 1 sec)
- However, A is gone, so C will loop asking A to retransmit #3 and will therefore never
install view B2 !
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8:36 a.m.
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Bela Ban updated JGRP-1509:
---------------------------
Fix Version/s: (was: 3.0.15)
GMS: low leave_timeout may cause incorrect view installation
------------------------------------------------------------
Key: JGRP-1509
URL: https://issues.jboss.org/browse/JGRP-1509
Project: JGroups
Issue Type: Bug
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 3.2
Attachments: tmp.xml
- {A}
- B joins, then C, the view is A2={A,B,C}
- *No* messages are sent
- GMS.leave_timeout=100
- NAKACK2.xmit_interval=1000
- A leaves gracefully (JChannel.disconnect())
- A multicasts B3={B,C}, the seqno is #3
- B discarded A#2 (view {A,B,C}), as it was not yet server
- B now asks A for retransmission of #2 before it can deliver #3 (the new view)
(- The retransmission kicks in ca. every 1 sec)
- However, A is gone, so C will loop asking A to retransmit #3 and will therefore never
install view B2 !
--
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8:52 a.m.
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]
Bela Ban resolved JGRP-1509.
----------------------------
Resolution: Done
GMS: low leave_timeout may cause incorrect view installation
------------------------------------------------------------
Key: JGRP-1509
URL: https://issues.jboss.org/browse/JGRP-1509
Project: JGroups
Issue Type: Bug
Reporter: Bela Ban
Assignee: Bela Ban
Fix For: 3.2
Attachments: tmp.xml
- {A}
- B joins, then C, the view is A2={A,B,C}
- *No* messages are sent
- GMS.leave_timeout=100
- NAKACK2.xmit_interval=1000
- A leaves gracefully (JChannel.disconnect())
- A multicasts B3={B,C}, the seqno is #3
- B discarded A#2 (view {A,B,C}), as it was not yet server
- B now asks A for retransmission of #2 before it can deliver #3 (the new view)
(- The retransmission kicks in ca. every 1 sec)
- However, A is gone, so C will loop asking A to retransmit #3 and will therefore never
install view B2 !
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Bela Ban (JIRA)