Github user keith-turner commented on the issue:
https://github.com/apache/accumulo/pull/121
> If the tablet server returns before master notices it's gone, master will
see it as a new empty tablet server.
One possible beginning of solution is to change the behavior of
`Master.gatherTabletInformation()` to do the following :
* Check if the instance matches the tablet server its talking to get
status. This could be done by adding the instance id to the returned Thrift
struct.
* If the instance id does not match, then add tserver to `badServers`.
This will prevent balancing (not sure if it will have other undesired
consequences).
This will detect a new tsever instance after obtaining info from zookeeper.
I am still looking at code and thinking about what else may need to be done.
@ShawnWalker offline you were wondering if it was possible to have info
about the same host+port twice in the master memory. I looked at how the
current code works and it attempts to prevent this. Below is what I found :
* The master uses `tserverStatus` for balancing which is populated at
[Master line
977](https://github.com/apache/accumulo/blob/97fdfc5912ce07615b9e85899675adc3d1b12578/server/master/src/main/java/org/apache/accumulo/master/Master.java#L977)
by calling `gatherTabletInformation()`
* `gatherTabletInformation()` calls `LiveTserverSet.getCurrentServers()`
which returns `currentInstances` which us updated by
[LiveTserverSet.checkServer()](https://github.com/apache/accumulo/blob/97fdfc5912ce07615b9e85899675adc3d1b12578/server/base/src/main/java/org/apache/accumulo/server/master/LiveTServerSet.java#L273).
The implementation of `checkServer()` uses the `current` map to ensure a
tserver+port only has one entry in `currentInstances`. The `current` map key
is based on the zookeeper lock name which is host+port as set on [TabletServer
line
2309](https://github.com/apache/accumulo/blob/97fdfc5912ce07615b9e85899675adc3d1b12578/server/tserver/src/main/java/org/apache/accumulo/tserver/TabletServer.java#L2309)
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