Rangsh commented on issue #12058:
URL: https://github.com/apache/seatunnel/issues/12058#issuecomment-5659578915

   @SEZ9 confirming the two remaining asks for closing out the flush-path 
experiment on this issue.
   
   ### 1. CPU / GC / after-side hsync (record completeness)
   
   Yes — the full numbers are in `AB-REPORT.md` in the A/B gist:
   
   https://gist.github.com/Rangsh/66008c5bad44fb05825db40198349175
   
   Pasting them here as well so the issue thread is complete even if the prior 
comment rendering was truncated:
   
   **CPU** (`profile_benchmarks.sh profile cpu`, diagnostic `-f 1`)
   
   | Side | samples | `HdfsWriter.flush` / `hsync` share (approx) |
   | --- | ---: | ---: |
   | BEFORE | 209 | ~0.48% |
   | AFTER | 189 | **~0.53%** |
   
   **GC** (`profile_benchmarks.sh profile gc`, diagnostic `-f 1`)
   
   | Side | Alloc/op | GC count | GC time |
   | --- | ---: | ---: | ---: |
   | BEFORE | 286,615 B/op | 1 | 5 ms |
   | AFTER | 286,729 B/op | 1 | 4 ms |
   
   No meaningful GC delta. Sync remains not CPU-hot on either side.
   
   ### 2. Flush-collapse experiment status for #12058
   
   I consider the flush-collapse experiment **concluded for #12058** on the 
agreed `file:///` / LocalFileSystem contract.
   
   - The isolated A/B was a **null result** (Score/CV did not improve; park / 
`InvocationFuture.get` hotspot remained).
   - That null result is **filesystem-specific** to this harness. I am **not** 
generalising it to a real HDFS/DFS client (where multi-sync + trailing `hflush` 
could still matter for cost under a separate contract).
   - I do **not** intend to rerun this same single-variable flush-collapse A/B 
against a non-local filesystem as part of closing #12058.
   - **#12081 stays Related only** and still cannot claim to address #12058 on 
the basis of this local null result.
   
   Please treat the storage sync / flush-collapse path as **ruled out** as the 
driver of the variance reported on this issue. Happy to keep the investigation 
focused next on the `InvocationFuture.get` / `LockSupport.park` wait.


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