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https://issues.apache.org/jira/browse/OAK-8512?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vikas Saurabh updated OAK-8512:
-------------------------------
Component/s: lucene
> Without prefetch CopyOnRead opens index files remotely even if they are
> locally available
> -----------------------------------------------------------------------------------------
>
> Key: OAK-8512
> URL: https://issues.apache.org/jira/browse/OAK-8512
> Project: Jackrabbit Oak
> Issue Type: Bug
> Components: lucene
> Reporter: Vikas Saurabh
> Priority: Trivial
>
> Without prefetch enabled, CopyOnReadDirectory schedules a copy of file when
> {{Directory#openInput}} is invoked. This happens even if there might a copy
> of file completely available already (maybe due to CopyOnWriteDirectory).
> While the scheduled copy would check if the file is valid already but by that
> time often index file are accessed remotely.
> The fix is fairly simple - don't schedule if file exists locally and passes
> our weak test that length matches what we expect \[0].
> But, since we strongly advise to enable prefetch, the priority of the issue
> is minor. Perf impact would be significant during application start so sev
> should high I guess.
> \[0]:
> {noformat}
> $ git diff
> oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/directory/CopyOnReadDirectory.java
> diff --git
> a/oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/directory/CopyOnReadDirectory.java
>
> b/oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/directory/CopyOnReadDirectory.java
> index b6b16286d2..d49e5d9ea7 100644
> ---
> a/oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/directory/CopyOnReadDirectory.java
> +++
> b/oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/directory/CopyOnReadDirectory.java
> @@ -126,11 +126,12 @@ public class CopyOnReadDirectory extends
> FilterDirectory {
> CORFileReference toPut = new CORFileReference(name);
> CORFileReference old = files.putIfAbsent(name, toPut);
> if (old == null) {
> - log.trace("[{}] scheduled local copy for {}", indexPath, name);
> - copy(toPut);
> + if (copy(toPut)) {
> + log.trace("[{}] scheduled local copy for {}", indexPath,
> name);
> + }
> }
>
> - //If immediate executor is used the result would be ready right away
> + //If immediate executor is used OR local file already existed, the
> result would be ready right away
> if (toPut.isLocalValid()) {
> log.trace("[{}] opening new local file {}", indexPath, name);
> return toPut.openLocalInput(context);
> @@ -145,7 +146,21 @@ public class CopyOnReadDirectory extends FilterDirectory
> {
> return local;
> }
>
> - private void copy(final CORFileReference reference) {
> + private boolean copy(final CORFileReference reference) {
> + // quick sanity check
> + if (reference.isLocalValid()) {
> + return false;
> + }
> + try {
> + String name = reference.name;
> + if (local.fileExists(name) && local.fileLength(name) ==
> remote.fileLength(name)) {
> + reference.markValid();
> + return false;
> + }
> + } catch (IOException e) {
> + // ignore
> + }
> +
> indexCopier.scheduledForCopy();
> executor.execute(new Runnable() {
> @Override
> @@ -154,6 +169,8 @@ public class CopyOnReadDirectory extends FilterDirectory {
> copyFilesToLocal(reference, true, true);
> }
> });
> +
> + return true;
> }
> {noformat}
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