[ACCUMULO-3774] Deadlock after recovering root tablet

• Type: Sub-task
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Fix Version/s: 1.8.0
• Labels: 1.7.0_QA

Environment

Hadoop 2.7.0, ZK 3.4.6, Accumulo 83d1b8388ad807d678c9a3a922e5025faa9a5933, 20 node m3.large EC2 cluster

• Assignee: Eric C. Newton
• Reporter: Keith Turner
• Created: 05/May/15 20:33
• Updated: 21/May/15 17:19
• Resolved: 21/May/15 17:19

Description

I started CI running against 1.7.0-SNAP. After CI ran for while I started agitation. Then everything froze up. The root tablet node was killed, the root tablet had a lot of walogs (will open a seperate issue for this), the root tablet was reloaded on another machine. However it hung up while loading with the following issue. The minor compaction after recovery was trying to write to the root tablet. This happened before the root tablet location was set.

"Minor compacting +r<<" daemon prio=10 tid=0x00000000046cd800 nid=0x3508 in Object.wait() [0x00007fb0ac3b1000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        at java.lang.Object.wait(Object.java:503)
        at org.apache.accumulo.core.client.impl.TabletServerBatchWriter.waitRTE(TabletServerBatchWriter.java:459)
        at org.apache.accumulo.core.client.impl.TabletServerBatchWriter.close(TabletServerBatchWriter.java:352)
        - locked <0x000000078d154840> (a org.apache.accumulo.core.client.impl.TabletServerBatchWriter)
        at org.apache.accumulo.core.client.impl.BatchWriterImpl.close(BatchWriterImpl.java:54)
        at org.apache.accumulo.server.util.MetadataTableUtil.markLogUnused(MetadataTableUtil.java:1131)
        at org.apache.accumulo.tserver.TabletServer.markUnusedWALs(TabletServer.java:3032)
        at org.apache.accumulo.tserver.TabletServer.minorCompactionFinished(TabletServer.java:2917)
        at org.apache.accumulo.tserver.tablet.DatafileManager.bringMinorCompactionOnline(DatafileManager.java:440)
        at org.apache.accumulo.tserver.tablet.Tablet.minorCompact(Tablet.java:956)
        at org.apache.accumulo.tserver.tablet.MinorCompactionTask.run(MinorCompactionTask.java:84)
        at org.apache.accumulo.tserver.tablet.Tablet.minorCompactNow(Tablet.java:1080)
        at org.apache.accumulo.tserver.TabletServer$AssignmentHandler.run(TabletServer.java:2124)
        at org.apache.accumulo.tserver.TabletServer$ThriftClientHandler$3.run(TabletServer.java:1510)

Issue Links

• is broken by: ACCUMULO-3423 speed up WAL roll-overs
• is related to: ACCUMULO-3775 Root tablet had 6,974 walogs