virajjasani commented on code in PR #5754:
URL: https://github.com/apache/hadoop/pull/5754#discussion_r1240904151
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/prefetch/SingleFilePerBlockCache.java:
##########
@@ -247,9 +305,46 @@ private Entry getEntry(int blockNumber) {
throw new IllegalStateException(String.format("block %d not found in
cache", blockNumber));
}
numGets++;
+ addToHeadOfLinkedList(entry);
return entry;
}
+ /**
+ * Add the given entry to the head of the linked list.
+ *
+ * @param entry Block entry to add.
+ */
+ private void addToHeadOfLinkedList(Entry entry) {
+ blocksLock.writeLock().lock();
+ try {
+ if (head == null) {
+ head = entry;
+ tail = entry;
+ }
+ if (entry != head) {
+ Entry prev = entry.getPrevious();
+ Entry nxt = entry.getNext();
+ if (prev != null) {
+ prev.setNext(nxt);
+ }
+ if (nxt != null) {
+ nxt.setPrevious(prev);
+ }
+ entry.setPrevious(null);
+ entry.setNext(head);
+ head.setPrevious(entry);
+ head = entry;
+ }
+ if (tail != null) {
+ while (tail.getNext() != null) {
+ tail = tail.getNext();
+ }
+ }
Review Comment:
i applied this patch temporarily to debug further but somehow head and tail
are getting screwed up:
```
diff --git
a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/prefetch/SingleFilePerBlockCache.java
b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/prefetch/SingleFilePerBlockCache.java
index ef685b54d30..1aad82ff9c2 100644
---
a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/prefetch/SingleFilePerBlockCache.java
+++
b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/prefetch/SingleFilePerBlockCache.java
@@ -306,6 +306,7 @@ private void addToHeadOfLinkedList(Entry entry) {
"Block num {} to be added to the head. Current head block num: {}
and tail block num: {}",
entry.blockNumber, head.blockNumber, tail.blockNumber);
if (entry != head) {
+ boolean isEntryTail = entry == tail;
Entry prev = entry.getPrevious();
Entry nxt = entry.getNext();
if (prev != null) {
@@ -318,10 +319,8 @@ private void addToHeadOfLinkedList(Entry entry) {
entry.setNext(head);
head.setPrevious(entry);
head = entry;
- }
- if (tail != null) {
- while (tail.getNext() != null) {
- tail = tail.getNext();
+ if (isEntryTail) {
+ tail = prev;
}
}
} finally {
```
however, somehow after eviction, the head and tail are getting screwed up,
still trying to understand what is going wrong and why this patch would not
work.
but i hope you were suggestion change like this one, correct?
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
