Make sure explanation is populated when .not_preferred logging is turned on #138325
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nicktindall
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:Distributed Coordination/Allocation
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Pinging @elastic/es-distributed-coordination (Team:Distributed Coordination) |
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DiannaHohensee
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Nov 20, 2025
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lgtm. Left some superficial suggestions.
...ain/java/org/elasticsearch/cluster/routing/allocation/allocator/BalancedShardsAllocator.java
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| if (notPreferredLogger.isDebugEnabled()) { | ||
| allocation.setDebugMode(RoutingAllocation.DebugMode.EXCLUDE_YES_DECISIONS); | ||
| } |
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| if (notPreferredLogger.isDebugEnabled()) { | |
| allocation.setDebugMode(RoutingAllocation.DebugMode.EXCLUDE_YES_DECISIONS); | |
| } | |
| allocation.setDebugMode(notPreferredLogger.isDebugEnabled() ? RoutingAllocation.DebugMode.EXCLUDE_YES_DECISIONS : oldDebugMode); | |
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I left this one because I don't think either form is significantly more or less readable, and it seems weird to set the value if it's not being changed.
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| * If a shard has moved we need to re-run the decision to check that it's still valid. If {@link #notPreferredLogger} is | ||
| * set to debug, we re-run the decision with explain turned on so we can populate the explanation in our log message | ||
| * | ||
| * @param index The index of the shard | ||
| * @param storedShardMovement The existing shard movement decision | ||
| * @param shardMoved True if a shard moved in this balancing round, false otherwise | ||
| * @return The move decision to act on |
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I found
"If a shard has moved we need to re-run the decision to check that it's still valid."
to be difficult to follow. Could it be replaced with something like
"If any shards in the cluster have been relocated since the stored shard movement was calculated, the move decision must be re-run to ensure it is still allowed."
...ain/java/org/elasticsearch/cluster/routing/allocation/allocator/BalancedShardsAllocator.java
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…ion/allocator/BalancedShardsAllocator.java Co-authored-by: Dianna Hohensee <artemisapple@gmail.com>
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Nov 26, 2025
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My previous attempt at logging more info on
NOT_PREFERREDdecisions that are acted on missed that we discard the explanation unlessdebugDecision()is turned on.This PR means we re-run
decideMove()withdebugDecision()turned on when the.not_preferredlogger is turned on and we're about to act on aNOT_PREFERREDdecision. I think this will be generally useful as we roll out more deciders capable of returningNOT_PREFERRED.