This reverts a change that Patrick Wendell made in
AVRO-595 when adding RPC tracing. I'm not sure why Patrick made that change there: perhaps it was essential but perhaps it was not. Unfortunately the trace tests are currently disabled in pom.xml, since they intermittently fail for reasons no one has yet debugged.
I re-enabled the trace tests in pom.xml and ran tests on unpatched trunk and they passed. Then I applied this patch and ran tests again and trace tests failed three times in a row. I reverted the patch and the trace tests then passed again. So superficially it appears that this patch breaks RPC tracing.
It would be nice to re-enable the trace tests by default. I think the problems are/were mostly caused by the use of fixed port numbers. In four runs they pass every time for me now.