Details
Major Description
There seems to be a code bug that can cause expiration of one region server carrying meta to bring down the master under certain case.
Here is the sequence of event.
a) The master detects the expiration of a region server on ZK, and starts to expire the region server.
b) Since the failed region server carries meta, the shutdown handler will call verifyAndAssignMetaWithRetries() during processing the expired rs.
c) In verifyAndAssignMeta(), there is a logic to verifyMetaRegionLocation
(!server.getMetaTableLocator().verifyMetaRegionLocation(server.getConnection(),
this.server.getZooKeeper(), timeout)) {
this.services.getAssignmentManager().assignMeta
(HRegionInfo.FIRST_META_REGIONINFO);
} else if (serverName.equals(server.getMetaTableLocator().getMetaRegionLocation(
this.server.getZooKeeper()))) {
throw new IOException("hbase:meta is onlined on the dead server "
+ serverName);
If we see the meta region is still alive on the expired rs, we throw an exception.
We do some retries (default 10x1000ms) for verifyAndAssignMeta.
If we still get the exception after retries, we abort the master.
2015-05-27 06:58:30,156 FATAL [MASTER_META_SERVER_OPERATIONS-bdvs1163:60000-0] master.HMaster: Master server abort: loaded coprocessors are: []
2015-05-27 06:58:30,156 FATAL [MASTER_META_SERVER_OPERATIONS-bdvs1163:60000-0] master.HMaster: verifyAndAssignMeta failed after10 times retries, aborting
java.io.IOException: hbase:meta is onlined on the dead server bdvs1164.svl.ibm.com,16020,1432681743203
at org.apache.hadoop.hbase.master.handler.MetaServerShutdownHandler.verifyAndAssignMeta(MetaServerShutdownHandler.java:162)
at org.apache.hadoop.hbase.master.handler.MetaServerShutdownHandler.verifyAndAssignMetaWithRetries(MetaServerShutdownHandler.java:184)
at org.apache.hadoop.hbase.master.handler.MetaServerShutdownHandler.process(MetaServerShutdownHandler.java:93)
at org.apache.hadoop.hbase.executor.EventHandler.run(EventHandler.java:128)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
2015-05-27 06:58:30,156 INFO [MASTER_META_SERVER_OPERATIONS-bdvs1163:60000-0] regionserver.HRegionServer: STOPPED: verifyAndAssignMeta failed after10 times retries, aborting
The problem happens when the expired is slow processing its own expiration or has a slow death, and is still able to respond to master's meta verification in the meantime