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https://issues.apache.org/jira/browse/HDDS-17032?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andrey Yarovoy updated HDDS-17032:
----------------------------------
Status: Patch Available (was: In Progress)
> Avoid building the `Preconditions` message on every write in
> `ECKeyOutputStream.ECChunkBuffers.addToDataBuffer`
> ---------------------------------------------------------------------------------------------------------------
>
> Key: HDDS-17032
> URL: https://issues.apache.org/jira/browse/HDDS-17032
> Project: Apache Ozone
> Issue Type: Bug
> Components: EC Client
> Reporter: Andrey Yarovoy
> Assignee: Andrey Yarovoy
> Priority: Minor
> Labels: pull-request-available
>
> **Problem**
> `ECChunkBuffers.addToDataBuffer` runs once per `write()` call segment. It
> checks the cell position with an eagerly
> concatenated message:
> ```java
> Preconditions.checkState(pos <= cellSize,
> "Position(" + pos + ") is greater than the cellSize(" + cellSize + ").");
> ```
> The message string is built (`StringConcatFactory` → `Integer.getChars`) on
> every call, even though the check
> virtually never fails. The number of calls scales with the caller's write
> size. freon's default `--buffer` is 4096
> bytes, which means about 65,000 calls per 256 MB key, and applications doing
> small writes pay the same.
> **Evidence** (real-cluster async-profiler wall profile, JDK 17, writer
> threads, on-CPU samples)
> | Writers | Share of writer CPU spent building this message |
> |---|---|
> | 1 rs-3-2-1024k writer | 0.79% |
> | 16 rs-3-2-1024k writers | 1.81% |
> **Proposal**
> Use Guava's template overload with primitive arguments, so nothing is
> formatted or boxed unless the check fails:
> ```java
> Preconditions.checkState(pos <= cellSize,
> "Position(%s) is greater than the cellSize(%s).", pos, cellSize);
> ```
> The other `Preconditions` call on the per-stripe path (`generateParityCells`)
> already uses a template. The
> eagerly built message in `close()` (`writeOffset == offset`) runs once per
> key, so it is not worth changing.
> **Compatibility**
> No behaviour change: the same exception type and message when the check fails.
> **Testing**
> Existing `TestECKeyOutputStream` / `TestOzoneECClient`. No new test is
> needed; the message text is unchanged.
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