Aias00 opened a new issue, #7590:
URL: https://github.com/apache/shenyu/issues/7590
## Summary
`LoadServiceDocEntryImpl.supportSwaggerPluginSet` is a `private static`
**non-volatile, non-final** field. It is written under `synchronized` on one
thread and read without any synchronization on a different thread, so the
reader is not guaranteed to ever observe the write.
## Evidence
`shenyu-admin/src/main/java/org/apache/shenyu/admin/service/manager/impl/LoadServiceDocEntryImpl.java`
```java
66: @SuppressWarnings("unchecked")
67: private static Set<String> supportSwaggerPluginSet =
Collections.emptySet();
```
**Writer** — startup path, `loadApiDocument()`:
```java
91: public synchronized void loadApiDocument() {
...
185: supportSwaggerPluginSet = new HashSet<>(pluginNames);
```
**Reader** — discovery / data-change path:
```java
208: if
(!supportSwaggerPluginSet.contains(discoverySyncData.getPluginName())) {
```
The read is reached from:
```
DiscoveryDataChangedEventSyncListener:138-139
→ eventPublisher.publishEvent(new
DataChangedEvent(ConfigGroupEnum.DISCOVER_UPSTREAM, ...))
→ DataChangedEventDispatcher:138
→ LoadServiceDocEntry.loadDocOnUpstreamChanged(...)
→
LoadServiceDocEntryImpl.getClusterLastUpdateInstance(DiscoverySyncData):208
```
i.e. a registry/sync callback thread, whereas the write happens on the admin
startup thread inside `ShenyuStandaloneService:49`. `synchronized` on the
writer does **not** create a happens-before edge for an unsynchronized reader,
so the JMM permits the reader to keep seeing the initial
`Collections.emptySet()` indefinitely.
## Impact
When the stale empty set is observed, `contains(...)` is always `false`, so
`getClusterLastUpdateInstance` returns `null` for every discovery upstream and
logs *"pluginName={} does not support pulling API documents."*. API document
pulling is then permanently disabled until the process restarts — and it may
stay broken even after a restart, since there is no ordering guarantee.
## Suggested fix
Make the field safely publishable. The minimal change:
```java
private static volatile Set<String> supportSwaggerPluginSet =
Collections.emptySet();
```
or better, make it an immutable instance field owned by the bean and
injected/refreshed explicitly, e.g.
```java
private final AtomicReference<Set<String>> supportSwaggerPluginSet =
new AtomicReference<>(Collections.emptySet());
```
with `supportSwaggerPluginSet.set(Set.copyOf(pluginNames))` on refresh.
`Set.copyOf` also removes the need for the `@SuppressWarnings("unchecked")` on
the field.
Please also consider whether the field needs to be `static` at all —
`LoadServiceDocEntryImpl` is a `@Service` singleton, so an instance field is
sufficient and avoids cross-instance sharing.
## Environment
- Branch: `master` @ `a7d80b7`
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