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https://issues.apache.org/jira/browse/HADOOP-19946?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18141902#comment-18141902
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ASF GitHub Bot commented on HADOOP-19946:
-----------------------------------------
anmolanmol1234 commented on code in PR #8830:
URL: https://github.com/apache/hadoop/pull/8830#discussion_r4523776346
##########
hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/ReadBufferManagerV2.java:
##########
@@ -890,43 +1119,128 @@ private ReadBuffer clearFromReadAheadQueue(final String
eTag,
*/
private int getBlockFromCompletedQueue(final String eTag, final long
position,
final int length, final byte[] buffer) throws IOException {
- ReadBuffer buf = getBufferFromCompletedQueue(eTag, position);
+ // Find any child buffer from the window that covers the requested position
+ ReadBuffer anyChild = getBufferFromCompletedQueue(eTag, position);
- if (buf == null) {
+ if (anyChild == null) {
+ // No buffer covers this position - cache miss
+ printTraceLog(
+ "No buffer in completed queue covers position: {} for eTag: {}",
+ position, eTag);
return 0;
}
- buf.startReading(); // atomic increment of refCount.
+ // Get the parent and its children
+ ReadBuffer parent = anyChild.getParentBuffer();
+
+ if (parent == null) {
+ // This is a standalone buffer (not part of a parent/child structure)
+ // Fall back to simple single-buffer copy
+ return copyFromSingleBuffer(anyChild, position, length, buffer);
Review Comment:
The READ_FAILED branch now calls endReading(), but this early return
doesn't, so the refcount leaks and the buffer can't be evicted. Please use
try/finally.
> ABFS: Enable data locality aware reads for Azure Blob Storage
> -------------------------------------------------------------
>
> Key: HADOOP-19946
> URL: https://issues.apache.org/jira/browse/HADOOP-19946
> Project: Hadoop Common
> Issue Type: New Feature
> Components: fs/azure
> Reporter: Manish Bhatt
> Assignee: Manish Bhatt
> Priority: Major
> Labels: pull-request-available
>
> Introduce data locality support in ABFS to improve read performance for Azure
> Blob Storage by routing read requests to the endpoint that hosts the required
> data range. The goal is to reduce latency, improve throughput, and make read
> operations more efficient for large files and distributed workloads. This
> work adds blob layout discovery, range-to-endpoint mapping, locality-aware
> range selection, and caching of layout metadata to avoid repeated lookups. It
> also enables segmented read-ahead aligned with locality boundaries and adds
> safeguards for concurrency, eviction, timeout handling, and failure
> propagation needed for reliable production-scale reads.
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