yandrey321 opened a new pull request, #10594:
URL: https://github.com/apache/ozone/pull/10594

   Before the fix the 6-argument constructor called fetchBlocks(), which issues 
a lookupKey RPC to OM when keyInfo is null. Because this.keyInfo is not 
assigned until after the 6-arg constructor returns, keyInfo was always null 
inside fetchBlocks(), so the RPC was always issued — even when the caller 
already had OmKeyInfo in hand.
   
   The fix reverses the chain: the 6-arg constructor delegates to the 7-arg 
with null, and the 7-arg constructor does the full initialization, assigning 
this.keyInfo before calling fetchBlocks().
   
   
   getChunkInfos() builds a standalone Pipeline containing only the selected 
nodes (data replica index 1 and all parity nodes). The old code used 
pipeline.toBuilder(), which copies the full EC nodeStatus map (all 5 or 9 
nodes). When setNodes() was then called with the smaller selected-node list, 
Pipeline.Builder detected the size mismatch and replaced the pipeline ID with 
PipelineID.randomId() — calling SecureRandom.nextBytes() on every file, even 
though setId(deterministicId) was not called at all in the old code.
   
   Because the pipeline ID was random per file, XceiverClientManager could 
never reuse a cached gRPC connection: every file opened a new connection 
regardless of whether it hit the same physical datanodes.
   
   The fix does two things:
   a) Compute a deterministic pipeline ID from the sorted UUIDs of the selected 
nodes
   b) Switch from toBuilder() to Pipeline.newBuilder() so that nodeStatus 
starts with null. Pipeline.Builder.setNodes() only calls PipelineID.randomId() 
when nodeStatus != null and the node count changes. With newBuilder() 
nodeStatus is always null, so the random replacement never triggers.
   
   ## What is the link to the Apache JIRA
   
   https://issues.apache.org/jira/browse/HDDS-15643
   
   ## How was this patch tested?
   
   1. Run existing unit and integration tests
   2. Run the benchmark FileChecksumBenchmark, 5 threads, 10 s warmup + 20 s 
measurement per combination. Two configurations (RS-3-2, RS-6-3) × three 
simulated OM latencies (0ms / 5 ms / 10 ms). The test is implemented in a way 
to limit test hit by 75% and intentionally force hit misses. 
   
   
   Config | Latency | Before | After | Ratio
   -- | -- | -- | -- | --
   RS-3-2 | 0ms | 62,203 | 80,691 | 1.30×
   RS-3-2 | 5ms | 405 | 637 | 1.57×
   RS-3-2 | 10ms | 204 | 416 | 2.04×
   RS-6-3 | 0ms | 42,613 | 53,837 | 1.26×
   RS-6-3 | 5ms | 348 | 812 | 2.34×
   RS-6-3 | 10ms | 184 | 416 | 2.26×
   
   
   The gain is largest at higher latencies because connection reuse (Fix 2) 
saves one full RPC round-trip per file. At 0 ms the dominant gain is Fix 1 
(halving OM calls). The OM/file counter confirms 2.00 → 1.00 for all rows; 
CacheHit% confirms 0% → 74-75% for all rows.


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