Copilot commented on code in PR #16869:
URL: https://github.com/apache/iotdb/pull/16869#discussion_r2589414080
##########
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/wal/allocation/AbstractNodeAllocationStrategy.java:
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@@ -57,6 +57,10 @@ protected AbstractNodeAllocationStrategy() {
protected IWALNode createWALNode(String identifier) {
try {
+ if (folderManager == null) {
+ folderManager = new FolderManager(
+ Arrays.asList(commonConfig.getWalDirs()),
DirectoryStrategyType.SEQUENCE_STRATEGY);
+ }
Review Comment:
This lazy initialization of `folderManager` is not thread-safe. The null
check and initialization need to be synchronized to prevent a race condition
where multiple threads could simultaneously detect `folderManager == null` and
create multiple FolderManager instances.
Consider using double-checked locking pattern:
```java
if (folderManager == null) {
synchronized (this) {
if (folderManager == null) {
folderManager = new FolderManager(
Arrays.asList(commonConfig.getWalDirs()),
DirectoryStrategyType.SEQUENCE_STRATEGY);
}
}
}
```
Alternatively, since all subclasses (ElasticStrategy, RoundRobinStrategy,
FirstCreateStrategy) already use `nodesLock` when calling `createWALNode`, you
could document that callers must hold their lock when calling this method.
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