zookeeper/zookeeper-specifications/protocol-spec/verification-statistics.md

Verification Statistics

Experiment configuration

Our statistical results include: diameter of the system states that have been traversed, the number of states that have been traversed, the number of different states that have been discovered, and the time spent in the experiment.

The machine configuration used in the experiment is 2.40 GHz, 10-core CPU, 64GB memory. The TLC version number is 1.7.0.

State space constraints in model checking

Due to the state space explosion in model checking and the complex actions of Zab protocol, as well as unlimited number of rounds and unlimited length of history, it is impossible to traverse all states.
We try to let models can tap into larger state space. See CONSTANT Parameters for details.

Verification statistics of model checking

Mode	TLC model	Diameter	num of states	time of checking(hh:mm:ss)
BFS	(2 servers,3 rounds,2 transactions)	59	7758091583	17:28:17
Simulation	(2 servers,3 rounds,2 transactions)	-	6412825222	17:07:20
BFS	(3 servers,2 rounds,2 transactions)	19	4275801206	09:40:08
Simulation	(3 servers,2 rounds,2 transactions)	-	10899460942	20:15:11
BFS	(3 servers,2 rounds,3 transactions)	22	8740566213	17:49:09
Simulation	(3 servers,2 rounds,3 transactions)	-	9639135842	20:10:00
BFS	(3 servers,3 rounds,2 transactions)	21	7079744342	14:17:45
Simulation	(3 servers,3 rounds,2 transactions)	-	6254964039	15:08:42
BFS	(4 servers,3 rounds,2 transactions)	16	5634112480	15:42:09
Simulation	(4 servers,3 rounds,2 transactions)	-	3883461291	15:52:03

Verification statistics with parameters (count of servers, MaxTotalRestartNum, MaxElectionNum, MaxTransactionNum)

Mode	TLC model	Diameter	num of states	time of checking(hh:mm:ss)
BFS	(2,2,3,2,termination)	55	10772649	00:02:21
BFS	(3,1,1,2)	45	9602018536	31:01:57

Issues

Besides, we have found several issues related to the ambiguous description of the Zab protocol. Details can be found at issues.md.