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https://issues.apache.org/jira/browse/HIVE-16451?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15978339#comment-15978339
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Peter Vary commented on HIVE-16451:
-----------------------------------
Thanks [~vihangk1] for taking the time to look at this!
Currently during the {{HiveStatement.runAsyncOnServer}} the {{isQueryClosed}}
flag is flipping:
- Constructor sets initially sets it to true
- The call {{closeClientOperation}} sets it to false
- The call {{initFlags}} sets it to true again
This happens even on the happy path, when there is no cancellation or errors,
and could generate the "Method getQueryLog() failed. The statement has been
closed or cancelled." warning message.
The getQueryLog, and runAsyncOnServer currently used parallel in very limited
situations, which might not lead to race conditions in other cases. At least I
have to find any concrete example, so I concentrated on the current problem.
Changing the HiveStatement to a thread safe one would be a big change. I could
do that, but was not sure that the community would agree with that - Shall we
do that [~vihangk1], [~ychena]? Would it worth the performance impact? Might
worth a letter to the dev list....
Thanks,
Peter
> Race condition between HiveStatement.getQueryLog and
> HiveStatement.runAsyncOnServer
> -----------------------------------------------------------------------------------
>
> Key: HIVE-16451
> URL: https://issues.apache.org/jira/browse/HIVE-16451
> Project: Hive
> Issue Type: Bug
> Components: Beeline, JDBC
> Affects Versions: 3.0.0
> Reporter: Peter Vary
> Assignee: Peter Vary
> Attachments: HIVE-16451.02.patch, HIVE-16451.03.patch,
> HIVE-16451.patch
>
>
> During the BeeLineDriver testing I have met the following race condition:
> - Run the query asynchronously through BeeLine
> - Querying the logs in the BeeLine
> In the following code:
> {code:title=HiveStatement.runAsyncOnServer}
> private void runAsyncOnServer(String sql) throws SQLException {
> checkConnection("execute");
> closeClientOperation();
> initFlags();
> [..]
> }
> {code}
> {code:title=HiveStatement.getQueryLog}
> public List<String> getQueryLog(boolean incremental, int fetchSize)
> throws SQLException, ClosedOrCancelledStatementException {
> [..]
> try {
> if (stmtHandle != null) {
> [..]
> } else {
> if (isQueryClosed) {
> throw new ClosedOrCancelledStatementException("Method getQueryLog()
> failed. The " +
> "statement has been closed or cancelled.");
> } else {
> return logs;
> }
> }
> } catch (SQLException e) {
> [..]
> }
> [..]
> }
> {code}
> The runAsyncOnServer {{closeClientOperation}} sets {{isQueryClosed}} flag to
> true:
> {code:title=HiveStatement.closeClientOperation}
> void closeClientOperation() throws SQLException {
> [..]
> isQueryClosed = true;
> isExecuteStatementFailed = false;
> stmtHandle = null;
> }
> {code}
> The {{initFlags}} sets it to false:
> {code}
> private void initFlags() {
> isCancelled = false;
> isQueryClosed = false;
> isLogBeingGenerated = true;
> isExecuteStatementFailed = false;
> isOperationComplete = false;
> }
> {code}
> If the {{getQueryLog}} is called after the {{closeClientOperation}}, but
> before the {{initFlags}}, then we will have a following warning if verbose
> mode is set to true in BeeLine:
> {code}
> Warning: org.apache.hive.jdbc.ClosedOrCancelledStatementException: Method
> getQueryLog() failed. The statement has been closed or cancelled.
> (state=,code=0)
> {code}
> This caused this fail:
> https://builds.apache.org/job/PreCommit-HIVE-Build/4691/testReport/org.apache.hadoop.hive.cli/TestBeeLineDriver/testCliDriver_smb_mapjoin_11_/
> {code}
> Error Message
> Client result comparison failed with error code = 1 while executing
> fname=smb_mapjoin_11
> 16a17
> > Warning: org.apache.hive.jdbc.ClosedOrCancelledStatementException: Method
> > getQueryLog() failed. The statement has been closed or cancelled.
> > (state=,code=0)
> {code}
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