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https://issues.apache.org/jira/browse/HADOOP-18740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17727999#comment-17727999
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ASF GitHub Bot commented on HADOOP-18740:
-----------------------------------------
steveloughran commented on code in PR #5675:
URL: https://github.com/apache/hadoop/pull/5675#discussion_r1211811893
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/prefetch/SingleFilePerBlockCache.java:
##########
@@ -99,6 +106,32 @@ public String toString() {
"([%03d] %s: size = %d, checksum = %d)",
blockNumber, path, size, checksum);
}
+
+ /**
+ * Take the read or write lock.
+ *
+ * @param lockType type of the lock.
+ */
+ void takeLock(LockType lockType) {
+ if (LockType.READ == lockType) {
+ this.lock.readLock().lock();
Review Comment:
remove the `this.`
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/prefetch/SingleFilePerBlockCache.java:
##########
@@ -99,6 +106,32 @@ public String toString() {
"([%03d] %s: size = %d, checksum = %d)",
blockNumber, path, size, checksum);
}
+
+ /**
+ * Take the read or write lock.
+ *
+ * @param lockType type of the lock.
+ */
+ void takeLock(LockType lockType) {
+ if (LockType.READ == lockType) {
+ this.lock.readLock().lock();
+ } else if (LockType.WRITE == lockType) {
+ this.lock.writeLock().lock();
+ }
+ }
+
+ /**
+ * Release the read or write lock.
+ *
+ * @param lockType type of the lock.
+ */
+ void releaseLock(LockType lockType) {
+ if (LockType.READ == lockType) {
+ this.lock.readLock().unlock();
Review Comment:
remove the `this.`
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/prefetch/SingleFilePerBlockCache.java:
##########
@@ -268,12 +310,15 @@ public void close() throws IOException {
int numFilesDeleted = 0;
for (Entry entry : blocks.values()) {
+ entry.takeLock(Entry.LockType.WRITE);
Review Comment:
should we be acquiring locks in close()?
good: no race condition in close
bad) the usual
also, L303: should closed be atomic?
> s3a prefetch cache blocks should be accessed by RW locks
> --------------------------------------------------------
>
> Key: HADOOP-18740
> URL: https://issues.apache.org/jira/browse/HADOOP-18740
> Project: Hadoop Common
> Issue Type: Sub-task
> Reporter: Viraj Jasani
> Assignee: Viraj Jasani
> Priority: Major
> Labels: pull-request-available
>
> In order to implement LRU or LFU based cache removal policies for s3a
> prefetched cache blocks, it is important for all cache reader threads to
> acquire read lock and similarly cache file removal mechanism (fs close or
> cache eviction) to acquire write lock before accessing the files.
> As we maintain the block entries in an in-memory map, we should be able to
> introduce read-write lock per cache file entry, we don't need coarse-grained
> lock shared by all entries.
>
> This is a prerequisite to HADOOP-18291.
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