collision-fast atomic broadcast
TRANSCRIPT
Collision-fast Atomic Broadcast
Rodrigo Schmidt (Facebook)Lasaro Camargos (UFU)Fernando Pedone (USI)
Consensus
Paxos
A
B
A
C
Proposers Learners
B
Acceptors
B
A
BConsensus in a nutshell
Atomic Broadcast
A
B
A
C
Proposers Learners
B
ACB
ACB
B
ACB
ACB
ACB
ACB
CB
ACB
AC
From Consensus to ABCast...
A
B
C
D
B
B D
Dealing with Collisions
A
B
C
D Paxos
Collision Fast approaches: limitations
• A single failure is supported
• All but one proposer are also acceptors
• Still have to retry
• Hiper-fast learningsingle failure, acceptor \in learners, or learner + hyper-fast proposer is a quorum
M-Consensus
1 A
2 B
3 A
4 C
Proposers LearnersAcceptors
1:A,2:B,3:A,4:C1:A,2:B,3:A,4:⊥
M-Consensus: all good
1 A
2
3 C
Collision-Fast Proposers
LearnersAcceptors
1 A
3 C
1st1 A1 A1 A1 A
3 C
2 ⊥2 ⊥2 ⊥
2nd
1A, 3C
1A, 3C
1A
1A, 3C1A, 3C
1A1A
3 C
1 A, 2⊥, 3 C
CFABcast...
AX
BZ
CY
DV
BDA XZCV Y
M-Consensus: failuresCollision-Fast Proposers
LearnersAcceptors
3C
1 A
1 A, 3 C
Coordinator 1 A, 3 C, 2 ⊥
1 A3C
1 A
1 A3C
1 A2⊥3C
1 A2⊥3 C
1 A2⊥3C
1 A2⊥3C
1 A2⊥3 C
1 A2⊥3C
Mencius
• similar communication pattern in the happy path
• conjecture: similar numbers
Why not use Mencius then?
Ours is trully collision fast
• Mencius is collision-fast until failures happen
• failures affect all future instances• reconfiguration vs reinstantiation
CFABcast recovers from failures instead of working around them, at greater expense
Summary
CFABCast: a (trully) collistion-fast atomic broadcast protocol
an Atomic Broadcast protocol that may (always) deliver the messages of multiple broadcasters within two communication steps
Collision-fast Atomic Broadcast
Rodrigo Schmidt (Facebook)Lasaro Camargos (UFU)Fernando Pedone (USI)