Don't do DNS resolving in .META. scanner for each row
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Key: HBASE-1918
URL: https://issues.apache.org/jira/browse/HBASE-1918
Project: Hadoop HBase
Issue Type: Improvement
Affects Versions: 0.20.1, 0.19.3
Reporter: Jean-Daniel Cryans
Assignee: Jean-Daniel Cryans
Fix For: 0.20.2, 0.21.0
While debugging a slow HBase on my new Mac, I found that my issue was that DNS
resolving was taking 10 seconds. Since Java 1.5, many people complained about
that and there's even a very commented issue
(http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5092063) that's closed but
still "active". In fact the real issue here is that when you a bad DNS
resolving (my router was acting on me, it's dead now) it waits for 10 seconds
or something like that (see previous link). So I was running PE and my meta
scanner was being slower and slower. In fact, everything was slow, even
starting the shell. So using jps I found that we are resolving DNS for each
scanned row in META in checkAssigned here:
{code}
if (sa != null && sa.length() > 0) {
serverName = HServerInfo.getServerName(sa, sc);
}
HServerInfo storedInfo = null;
{code}
HSI.getServerName here creates a new HServerAddress which resolves DNS in its
depths and it's not even necessary, we use it just to split the server IP and
port.
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