Before learner receives the leader UPTODATE request, the loop run like this:
case Leader.PROPOSAL:
PacketInFlight pif = new PacketInFlight();
pif.hdr = new TxnHeader();
pif.rec = SerializeUtils.deserializeTxn(qp.getData(),
pif.hdr);//deserialize data
packetsNotCommitted.add(pif);//add to packetsNotCommitted queue
break;
case Leader.COMMIT:
pif = packetsNotCommitted.peekFirst();
if (!writeToTxnLog) {//only use SNAP synchronize way, writeToTxnLog
will be false
zk.processTxn(pif.hdr, pif.rec);//only update the memory data
tree,not write transcation log
packetsNotCommitted.remove();
} else {//use DIFF synchronize way
packetsCommitted.add(qp.getZxid());//add to packetsCommitted queue
}
break;
If use DIFF way to synchronize data,the real data synchronization has not
start before zk.startup
Is I understand something wrong?
Michael Han <[email protected]> 于2018年6月18日周一 下午12:28写道：
> Data synchronization is already done if the execution hits the zk.startup
> (note the previous while loop will only break if learner receives leaders
> up to date message).
>
> On Wed, Jun 13, 2018 at 10:51 PM, yuzhou li <[email protected]> wrote:
>
> > The main code is at Learner.java syncWithLeader like this:
> > if (qp.getType() == Leader.DIFF) {
> > LOG.info("Getting a diff from the leader 0x{}",
> > Long.toHexString(qp.getZxid()));
> > snapshotNeeded = false;
> > }
> >
> > case Leader.COMMITANDACTIVATE:
> > if (!writeToTxnLog) {
> > if (pif.hdr.getZxid() != qp.getZxid()) {
> > LOG.warn("Committing " + qp.getZxid() + ", but next
> > proposal is " + pif.hdr.getZxid());
> > } else {
> > zk.processTxn(pif.hdr, pif.rec);
> > packetsNotCommitted.remove();
> > }
> > } else {
> > packetsCommitted.add(qp.getZxid());
> > }
> > break;
> >
> > zk.startup();//this will create the processor chain,and waiting
> > request will be processed after the zk startup
> >
> > if (zk instanceof FollowerZooKeeperServer) {
> > FollowerZooKeeperServer fzk = (FollowerZooKeeperServer)zk;
> > for(PacketInFlight p: packetsNotCommitted) {
> > fzk.logRequest(p.hdr, p.rec);
> > }
> > for(Long zxid: packetsCommitted) {
> > fzk.commit(zxid);
> > }
> > }
> >
> > yuzhou li <[email protected]> 于2018年6月14日周四 下午1:47写道：
> > >
> > > Hi,everyone.
> > > I git pull the tag release-3.5.4 from github. Before I read the
> > > 3.4.6 version code, I found 3.5.4 has some changes when the learner
> > > synchronzied with leader.
> > > If using DIFF way to synchronize histories, the follower or observer
> > > will put the data in a queue, then start zkServer, then get all data
> > > from the queue, and process the data as a normol request,after all
> > > data is processd, the server is synchronized with leader completely.
> > > But at zkServe start moment, the client request can be process by this
> > > server,but this server has no data because the data is stored at the
> > > queue currently, so the client will read dirty data.
> > > Does this situation will happend?Or there is some point I has not
> > find?
> >
>
