Shulou(Shulou.com)06/02 Report--

This article mainly introduces "the process of pre-starting zk service and starting election". In daily operation, I believe many people have doubts about the process of pre-starting zk service and starting election. The editor has consulted all kinds of materials and sorted out simple and useful operation methods. I hope it will be helpful to answer the doubts about "pre-start zk service and start the election process". Next, please follow the editor to study!

QuorumPeerMain class public static void main (String [] args) {QuorumPeerMain main = new QuorumPeerMain (); try {main.initializeAndRun (args);} catch (IllegalArgumentException e) {LOG.error ("Invalid arguments, exiting abnormally", e); LOG.info (USAGE); System.err.println (USAGE); System.exit (ExitCode.INVALID_INVOCATION.getValue ()) } catch (ConfigException e) {LOG.error ("Invalid config, exiting abnormally", e); System.err.println ("Invalid config, exiting abnormally"); System.exit (ExitCode.INVALID_INVOCATION.getValue ());} catch (DatadirException e) {LOG.error ("Unable to access datadir, exiting abnormally", e); System.err.println ("Unable to access datadir, exiting abnormally") System.exit (ExitCode.UNABLE_TO_ACCESS_DATADIR.getValue ());} catch (AdminServerException e) {LOG.error ("Unable to start AdminServer, exiting abnormally", e); System.err.println ("Unable to start AdminServer, exiting abnormally"); System.exit (ExitCode.ERROR_STARTING_ADMIN_SERVER.getValue ());} catch (Exception e) {LOG.error ("Unexpected exception, exiting abnormally", e) System.exit (ExitCode.UNEXPECTED_ERROR.getValue ());} LOG.info ("Exiting normally"); System.exit (ExitCode.EXECUTION_FINISHED.getValue ());}

Pre-start

1. Started by QuorumPeerMain

2 configure multiple nodes in the case of parsing profile cluster, and start cleaning DatadirCleanupManager

2.1Create zk data Manager (FileTxnSnapLog)

3 to judge whether it is a cluster or a stand-alone mode

4 initialize quorumPeer through configuration, including (ElectionType,zkdatabase,quorumVerifier,cnxnFactory,learnerType, etc.)

Is the trustee of the zk server instance. QuorumPeer will constantly check the running status of the current server instance and initiate a leader election.

5 create an in-memory database,zkdb to manage all session records, transaction information and dataTree data

6 initialize QuorumPeer instance, register FileTxnSnapLog,ServerCnxnFactory,ZkDatabase with QuorumPeer, configure parameter server list, election algorithm and timeout during election, etc.

7 load database loadDataBase ()

8 start serverCnxn connection

7-8 in QuorumPeer

Public synchronized void start () {if (! getView (). ContainsKey (myid)) {throw new RuntimeException ("My id" + myid + "not in the peer list");} / / load database loadDataBase (); / / start service connection factory startServerCnxnFactory (); try {adminServer.start ();} catch (AdminServerException e) {LOG.warn ("Problem starting AdminServer", e) System.out.println (e);} / / start the election of startLeaderElection (); startJvmPauseMonitor (); super.start ();}

Leader election

1 initialize the leader election algorithm

2 in cluster mode, zookeeper will first base on its own server id (sid) and the latest transaction id (zxid) (lastLoggedZxid)

3 and the current server epoch (currentEpoch) to create ballots

4 during the creation process, each server will vote for itself, and then, according to the zoo.cfg configuration, create the corresponding leader election algorithm

Zookeeper provides three algorithms (LeaderElection,AuthFastLeaderElection,FastLeaderElection) by default, which can be configured through the electionArg attribute of zoo.cfg.

5 but now the FastLeaderElection election algorithm is supported by default

During the initialization phase, zk creates the network io manager QuorumCnxnManager needed for the election, and listens to the election designated port, waiting for other election services to connect.

At this point, the study on "zk service pre-start and start the election process" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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