Sto cercando una spiegazione semplice del algoritmo di Paxos che può essere usato per raggiungere il consenso in un ambiente distribuito (possibilmente rete peer to peer).
Ogni spiegazione che ho incontrato finora è stata una lettura difficile di più pagine. Sto cercando una spiegazione semplificata che mantenga ancora i principi fondamentali.
Ho trovato questa spiegazione nel contesto di Cassandra utili transazioni leggere.
Prepare/promise is the core of the algorithm. Any node may propose a value; we call that node the leader. (Note that many nodes may attempt to act as leaders simultaneously! This is not a “master” role.) The leader picks a ballot and sends it to the participating replicas. If the ballot is the highest a replica has seen, it promises to not accept any proposals associated with any earlier ballot. Along with that promise, it includes the most recent proposal it has already received.
If a majority of the nodes promise to accept the leader’s proposal, it may proceed to the actual proposal, but with the wrinkle that if a majority of replicas included an earlier proposal with their promise, then that is the value the leader must propose. Conceptually, if a leader interrupts an earlier leader, it must first finish that leader’s proposal before proceeding with its own, thus giving us our desired linearizable behavior.
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