Table of Contents
Always start with the master log (TODO: Which lines?). Normally it’s just printing the same lines over and over again. If not, then there’s an issue. Google or search-hadoop.com should return some hits for those exceptions you’re seeing.
An error rarely comes alone in Apache HBase, usually when something gets screwed up what will follow may be hundreds of exceptions and stack traces coming from all over the place. The best way to approach this type of problem is to walk the log up to where it all began, for example one trick with RegionServers is that they will print some metrics when aborting so grepping for Dump should get you around the start of the problem.
RegionServer suicides are “normal”, as this is what they do when something goes wrong.
For example, if ulimit and max transfer threads (the two most important initial settings, see
Limits on Number of Files and Processes (ulimit)
and Section 188.8.131.52, “
changed, it will make it impossible at some point for DataNodes
to create new threads that from the HBase point of view is seen as if HDFS was gone. Think
about what would happen if your MySQL database was suddenly unable to access files on your
local file system, well it’s the same with HBase and HDFS. Another very common reason to see
RegionServers committing seppuku is when they enter prolonged garbage collection pauses that
last longer than the default ZooKeeper session timeout. For more information on GC pauses, see
part blog post by Todd Lipcon and Section 184.108.40.206, “Long GC pauses” above.