priyen-stripe opened a new issue, #17646:
URL: https://github.com/apache/pinot/issues/17646
**Description:**
When running a table rebalance on an OFFLINE table that has consistent
data push and segments actively being pushed, a NullPointerException can occur
in TableRebalancer.doRebalance().
**Environment:**
- Apache Pinot version: 1.5 (a commit from jan 14. 2026)
- Table type: OFFLINE with consistent segment push
**Steps to Reproduce:**
1. Have an OFFLINE table with consistent data push
2. Actively push segments, start a rebalance on the table (e.g., to move
it to a different server pool)
3. While the rebalancer is waiting for EV-IS convergence, a scheduled
segment refresh runs and deletes/replaces an existing segment
4. The rebalancer detects the IdealState version change and attempts to
re-check segment states
5. NPE is thrown
The rebalancer throws a NullPointerException and the rebalance fails. This
makes it difficult to rebalance tables that have continuous ingestion without
pausing the data pipeline.
**Stack Trace:**
java.util.concurrent.CompletionException: java.lang.NullPointerException:
Cannot invoke "java.util.Map.equals(Object)" because "oldInstanceStateMap" is
null
at
java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:315)
at
java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:320)
at
java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1770)
at
java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
at
java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
at java.base/java.lang.Thread.run(Thread.java:1583)
Caused by: java.lang.NullPointerException: Cannot invoke
"java.util.Map.equals(Object)" because "oldInstanceStateMap" is null
at
org.apache.pinot.controller.helix.core.rebalance.TableRebalancer.doRebalance(TableRebalancer.java:634)
at
org.apache.pinot.controller.helix.core.rebalance.TableRebalancer.rebalance(TableRebalancer.java:197)
at
org.apache.pinot.controller.helix.core.rebalance.TableRebalanceManager.rebalanceTable(TableRebalanceManager.java:221)
at
org.apache.pinot.controller.helix.core.rebalance.TableRebalanceManager.rebalanceTable(TableRebalanceManager.java:127)
at
org.apache.pinot.controller.helix.core.rebalance.TableRebalanceManager.lambda$rebalanceTableAsync$0(TableRebalanceManager.java:158)
at
java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1768)
... 3 more
**Relevant Logs:**
INFO Successfully updated the IdealState
INFO Starting EV-IS convergence check loop, 378 unique segments to
monitor in current step
INFO ExternalView converged in 25088ms, with 0 extensions
INFO IdealState version changed while waiting for ExternalView to
converge, re-calculating the target assignment
INFO Segment state changed in IdealState from: {Server_xyz_8098=ONLINE}
to: null for segment: <segment_name>, re-calculating the target assignment
based on the new IdealState
ERROR Caught exception/error while rebalancing table
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