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Posted to issues-all@impala.apache.org by "Quanlong Huang (Jira)" <ji...@apache.org> on 2021/03/18 01:04:00 UTC
[jira] [Work started] (IMPALA-10579) Deadloop in table metadata
loading when using an invalid RemoteIterator
[ https://issues.apache.org/jira/browse/IMPALA-10579?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Work on IMPALA-10579 started by Quanlong Huang.
-----------------------------------------------
> Deadloop in table metadata loading when using an invalid RemoteIterator
> -----------------------------------------------------------------------
>
> Key: IMPALA-10579
> URL: https://issues.apache.org/jira/browse/IMPALA-10579
> Project: IMPALA
> Issue Type: Bug
> Components: Catalog
> Affects Versions: Impala 3.4.0
> Reporter: Quanlong Huang
> Assignee: Quanlong Huang
> Priority: Critical
>
> The file listing thread in catalogd will go into a dead loop if it gets a RemoteIterator on a non-existing path. The first call of the RemoteIterator.hasNext() will throw a FileNotFoundException. However, this exception will be catched and the loop will continue, which results in a dead loop. Related codes: [https://github.com/apache/impala/blob/d89c04bf806682d3449c566ce979632bd2ac5b29/fe/src/main/java/org/apache/impala/common/FileSystemUtil.java#L789-L814]
> {code:java}
> static class FilterIterator implements RemoteIterator<FileStatus> {
> ...
> public boolean hasNext() throws IOException {
> ...
> while (curFile_ == null) {
> FileStatus next;
> try {
> if (!baseIterator_.hasNext()) return false; // <---- throws FileNotFoundException
> ...
> next = baseIterator_.next();
> } catch (FileNotFoundException ex) {
> ...
> LOG.warn(ex.getMessage());
> continue; // <--------- catch the exception and continue into a dead loop
> }
> if (!isInIgnoredDirectory(startPath_, next)) {
> curFile_ = next;
> return true;
> }
> }
> return true;
> }
> {code}
> *When will the path to be loading not exist?*
> It happens when metadata (table/partition location) in HMS still have the path. But it's actually removed from the storage.
> *When will impala get such an invalid RemoteIterator?*
> For FileSystem implementations that don't override the FileSystem#listStatusIterator() interface, e.g. S3AFileSystem before HADOOP-17281, AzureBlobFileSystem, and GoogleHadoopFileSystem.
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