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Ted Yu commented on HBASE-18955: -------------------------------- Please include trivial change in hbase-server module for better QA coverage. > HBase client queries stale hbase:meta location with half-dead RegionServer > -------------------------------------------------------------------------- > > Key: HBASE-18955 > URL: https://issues.apache.org/jira/browse/HBASE-18955 > Project: HBase > Issue Type: Bug > Components: Client > Affects Versions: 1.1.12 > Reporter: Josh Elser > Assignee: Josh Elser > Priority: Critical > Fix For: 1.1.13 > > Attachments: HBASE-18995.001.branch-1.1.patch > > > Have been investigating a case with [~tedyu] where, when a RegionServer > becomes "hung" (for no specific reason -- not the point), the client becomes > stuck trying to talk to this RegionServer, never exiting. This was eventually > tracked down to HBASE-15645. However, in testing the fix, I found that there > is an additional problem which only affects branch-1.1. > When the RegionServer in the "half-dead" state is also hosting meta, the > hbase client (both the one trying to read data, but also the client in the > Master trying to read meta in SSH) get stuck repeatedly trying to read meta > from the old location after meta has been reassigned. > The general test outline goes like this: > * Start at least 2 regionservers > * Load some data into a table ({{hbase pe}} is great) > * Find a region that is hosted by the same RS that is hosting meta > * {{kill -SIGSTOP}} that RS hosting the user region and meta > * Issue a {{get}} in the hbase-shell trying to read from that user region > The expectation is that the ZK lock will expire for the STOP'ed RS, meta will > be reassigned, then the user regions will be reassigned, then the client will > get the result of the get without seeing an error (as long as this happens > within the hbase.client.operation.timeout value, of course). > We see this happening on HBase 1.2.4 and 1.3.2-SNAPSHOT, but, on > 1.1.13-SNAPSHOT, the Master gets up to re-assigning meta, but then gets stuck > trying to read meta from the STOP'ed RS instead of where it re-assigned it. > Because of this, the regions stay in transition until the master is restarted > or the STOP'ed RS is CONT'ed. My best guess is that when the RS sees the > {{SIGCONT}}, it immediately begins stopping which is enough to kick the > client into refreshing the region location cache. -- This message was sent by Atlassian JIRA (v6.4.14#64029)