davidradl commented on code in PR #26415:
URL: https://github.com/apache/flink/pull/26415#discussion_r2033089874
##########
flink-state-backends/flink-statebackend-forst/src/main/java/org/apache/flink/state/forst/fs/cache/CachedDataInputStream.java:
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@@ -125,39 +127,53 @@ private FSDataInputStream getStream() throws IOException {
StreamStatus.CACHED_CLOSED);
streamStatus = StreamStatus.CACHED_CLOSED;
}
- // try reopen
- tryReopen();
- stream = tryGetCacheStream();
- if (stream != null) {
- fileBasedCache.incHitCounter();
- return stream;
- }
- fileBasedCache.incMissCounter();
- return originalStream;
- } else if (streamStatus == StreamStatus.ORIGINAL) {
- fileBasedCache.incMissCounter();
- return originalStream;
- } else {
- if (streamStatus == StreamStatus.CACHED_OPEN) {
- stream = tryGetCacheStream();
+ // if it is CACHED_CLOSED, we try to reopen it
+ if (streamStatus == StreamStatus.CACHED_CLOSED) {
+ stream = tryReopen();
if (stream != null) {
fileBasedCache.incHitCounter();
return stream;
}
+ fileBasedCache.incMissCounter();
+ return originalStream;
+ } else if (streamStatus == StreamStatus.ORIGINAL) {
+ fileBasedCache.incMissCounter();
+ return originalStream;
+ } else {
+ // The stream is not closed, but we cannot get the cache
stream.
+ // Meaning that it is in the process of closing, but the
status has not been
+ // updated. Thus, we'd better retry here until it reach a
stable state (CLOSING).
+ Thread.yield();
}
- fileBasedCache.incMissCounter();
- return originalStream;
}
}
+ /**
+ * Attempts to retrieve the cached stream if it is open and the reference
count is greater than
+ * zero. If successful, it retains the reference count and returns the
cached stream. The
+ * invoker must ensure to release the stream after use.
+ *
+ * @return the cached stream if available, or null if not
+ */
private FSDataInputStream tryGetCacheStream() {
if (streamStatus == StreamStatus.CACHED_OPEN && cacheEntry.tryRetain()
> 0) {
- return fsdis;
+ // Double-check the status as it may change after retain.
Review Comment:
what do we mean by retain here? Do we mean retry?
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