terrymanu commented on issue #35580:
URL:
https://github.com/apache/shardingsphere/issues/35580#issuecomment-3643026622
## Problem Understanding
JFR shows SecureRandom causing blocking and performance regression in
tableless unicast routing. You want to understand the reason and current
status, with official documentation references.
## Root Cause
PR #35411 replaced ThreadLocalRandom with new SecureRandom() in a
high-frequency path. SecureRandom construction and number generation depend on
entropy sources and synchronization, which can block under load, causing slower
performance. PR #35414 reverted this change.
## Analysis
- Current master
(infra/route/core/.../TablelessDataSourceUnicastRouteEngine.java) has already
restored ThreadLocalRandom:
```java
private String getRandomDataSourceName(final Collection<String>
dataSourceNames) {
return new
ArrayList<>(dataSourceNames).get(ThreadLocalRandom.current().nextInt(dataSourceNames.size()));
}
```
- Impact scope: only snapshots between commit 8f5b7a8d (introduced
SecureRandom) and 07209678 (reverted) were affected; released 5.5.2 and current
master/5.5.3-SNAPSHOT already contain the rollback.
## Conclusion
The performance regression has been reverted; current master no longer has
this issue. If your runtime build comes from that brief window of commits,
please upgrade to an official release (≥5.5.2) or current
master/5.5.3-SNAPSHOT. If you’re already on those versions, no further action
is needed.
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