Coordinator fix balancer stuck#5987
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jon-wei merged 6 commits intoapache:masterfrom Jul 12, 2018
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test failure appears related |
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Current failures seem unrelated |
jon-wei
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Jul 12, 2018
clintropolis
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Jul 18, 2018
* this will fix it * filter destinations to not consider servers already serving segment * fix it * cleanup * fix opposite day in ImmutableDruidServer.equals * simplify
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This appears to happen when the balancer runs before the metadata manager polls the metadata database, resulting in the
ifstatement inside of theforloop to never get satisfied. Added max iterations to give up and log about it. I was able to duplicate in local debug cluster, which is where I should've caught this in the first place, my bad.Fixes #5981
It also fixes issues with correctly counting 'moved' and 'unmoved' segments and optimizes cost calculation by removing servers which already have a replica of a segment from being considered as a target server to move a segment to. Previously, sometimes servers which already had the segment would be selected as the 'best' destination to move the segment to, but then the move function would bail out and not do anything, incorrectly counting a segment as 'moved' but without any corresponding log.
Finally
ImmutableDruidServer.equalswas broken, but doesn't appear to be called anywhere other than in this change, so maybe not a big deal (most things deal withServerHolderwhose.equalspicks some properties of
ImmutableDruidServerinstead of calling it's.equalsdirectly.