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https://issues.apache.org/jira/browse/SENTRY-2299?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16540660#comment-16540660
]
Na Li commented on SENTRY-2299:
-------------------------------
[~Tagar] do you have a lot of external tables, and rename them a lot with
different paths? From following code, sentry skips creating entry for those
tables.
The most likely reason why oldEntry is null is because the entry is not created
due to its path outside of the prefix, not because some delta change was lost.
This also explains why restarting NN and getting full path snapshot from Sentry
server does not help because the entry of an external table will still be null
for rename.
Then the fix will be to check if oldEntry is null or not. If no, then move its
entry to the new path.
{code}
public Entry createAuthzObjPath(List<String> pathElements, String authzObj)
{
Entry entry = null;
Entry prefix = findPrefixEntry(pathElements);
if (prefix != null) {
// we only create the entry if is under a prefix, else we ignore it
entry = createChild(pathElements, EntryType.AUTHZ_OBJECT, authzObj);
} else {
if (LOG.isDebugEnabled()) {
LOG.debug(String.format("%s: createAuthzObjPath(%s, %s): outside of
prefix, skipping", <- skip creating entry for external tables
this, authzObj, pathElements));
}
}
return entry;
}
{code}
> NPE In Sentry HDFS Sync Plug
> ----------------------------
>
> Key: SENTRY-2299
> URL: https://issues.apache.org/jira/browse/SENTRY-2299
> Project: Sentry
> Issue Type: Bug
> Components: Sentry
> Affects Versions: 2.1.0
> Reporter: Na Li
> Assignee: Na Li
> Priority: Major
>
> Sentry HDFS ACL synchronization stopped working and throws
> NullPointerException. The HDFS logs showed repeating errors like the
> following:
> {code}
> 11:16:15.743 AM WARN SentryAuthorizationInfo
> Failed to update, will retry in [30000]ms, error:
> java.lang.NullPointerException
> at org.apache.sentry.hdfs.HMSPaths$Entry.access$200(HMSPaths.java:146)
> at org.apache.sentry.hdfs.HMSPaths.renameAuthzObject(HMSPaths.java:879)
> at
> org.apache.sentry.hdfs.UpdateableAuthzPaths.applyPartialUpdate(UpdateableAuthzPaths.java:118)
> at
> org.apache.sentry.hdfs.UpdateableAuthzPaths.updatePartial(UpdateableAuthzPaths.java:81)
> at
> org.apache.sentry.hdfs.SentryAuthorizationInfo.processUpdates(SentryAuthorizationInfo.java:211)
> at
> org.apache.sentry.hdfs.SentryAuthorizationInfo.update(SentryAuthorizationInfo.java:139)
> at
> org.apache.sentry.hdfs.SentryAuthorizationInfo.run(SentryAuthorizationInfo.java:232)
> at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
> at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
> at
> java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
> at
> java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
> at java.lang.Thread.run(Thread.java:748)
> The customer checked the Sentry logs and didn't see any corresponding errors.
> The issue stopped occurring, apparently not through any specific user
> intervention. (The customer tried manually failing over the active NameNode,
> with no change.)
> {code}
> Arjun mentioned the reason is that some delta update from sentry server was
> lost, so the oldEntry at line HMSPaths.java:879 was null. That caused null
> exception.
> {code}
> void renameAuthzObject(String oldName, List<List<String>> oldPathElems,
> String newName, List<List<String>> newPathElems) {
> if (LOG.isDebugEnabled()) {
> LOG.debug(String.format("%s renameAuthzObject({%s, %s} -> {%s, %s})",
> this, oldName, assemblePaths(oldPathElems), newName,
> assemblePaths(newPathElems)));
> }
> if (oldPathElems == null || oldPathElems.isEmpty() ||
> newPathElems == null || newPathElems.isEmpty() ||
> newName == null || newName.equals(oldName)) {
> LOG.warn(String.format("%s renameAuthzObject({%s, %s} -> {%s, %s})" +
> ": invalid inputs, skipping",
> this, oldName, assemblePaths(oldPathElems), newName,
> assemblePaths(newPathElems)));
> return;
> }
> // if oldPath == newPath, that is path has not changed as part of rename
> and hence new table
> // needs to have old paths => new_table.add(old_table_partition_paths)
> List<String> oldPathElements = oldPathElems.get(0);
> List<String> newPathElements = newPathElems.get(0);
> if (!oldPathElements.equals(newPathElements)) {
> Entry oldEntry = root.find(oldPathElements.toArray(new String[0]),
> false);
> Entry newParent = root.createParent(newPathElements);
> oldEntry.moveTo(newParent, newPathElements.get(newPathElements.size() -
> 1)); -> oldEntry is null
> }
> {code}
> There are several possible reasons why some delta changes are lost.
> {code}
> 1. Sentry server does not save the rename update as delta update. The chance
> is really low
> 2. The delta change is lost from sentry server to name node plugin. The
> chance is also low
> 3. When applying delta change about old entry, it is lost
> {code}
> The fix for this issue
> 1. Check if oldEntry is null. If so, don't call oldEntry.moveTo. Instead,
> throw exception, which will be caught by its caller and causes sentry client
> at name node plugin gets path full snapshot from sentry server.
> 2. Find out why the oldEntry is null and fix it.
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