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https://issues.apache.org/jira/browse/HIVE-26875?focusedWorklogId=834941&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-834941
]
ASF GitHub Bot logged work on HIVE-26875:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 20/Dec/22 22:52
Start Date: 20/Dec/22 22:52
Worklog Time Spent: 10m
Work Description: jfsii commented on code in PR #3887:
URL: https://github.com/apache/hive/pull/3887#discussion_r1053821695
##########
ql/src/test/org/apache/hadoop/hive/ql/lockmgr/TestDbTxnManager2.java:
##########
@@ -42,6 +42,7 @@
import org.apache.hadoop.hive.ql.Driver;
import org.apache.hadoop.hive.ql.QueryState;
import org.apache.hadoop.hive.ql.io.AcidUtils;
+import org.apache.hadoop.hive.ql.metadata.HiveException;
Review Comment:
I don't think this is used, remove it.
##########
ql/src/java/org/apache/hadoop/hive/ql/Driver.java:
##########
@@ -555,7 +551,14 @@ private void prepareContext() throws
CommandProcessorException {
String originalCboInfo = context != null ? context.cboInfo : null;
if (context != null && context.getExplainAnalyze() !=
AnalyzeState.RUNNING) {
// close the existing ctx etc before compiling a new query, but does not
destroy driver
- closeInProcess(false);
+ if (!driverContext.isRetrial()) {
+ closeInProcess(false);
+ } else {
+ // On retrail we need to maintain information from the prior context.
Such
Review Comment:
fix typo
##########
ql/src/test/org/apache/hadoop/hive/ql/lockmgr/TestDbTxnManager2.java:
##########
@@ -2465,6 +2468,113 @@ private void
testConcurrent2MergeUpdatesConflict(boolean slowCompile) throws Exc
Assert.assertTrue("Lost Update", isEqualCollection(res, asList("earl\t10",
"amy\t10")));
}
+ // The intent of this test is to cause multiple conflicts to the same query
to test the conflict retry functionality.
+ @Test
+ public void testConcurrentConflictRetry() throws Exception {
+ dropTable(new String[]{"target"});
+
+ driver2.getConf().setBoolVar(HiveConf.ConfVars.TXN_WRITE_X_LOCK, true);
+ driver.run("create table target(i int) stored as orc tblproperties
('transactional'='true')");
+ driver.run("insert into target values (1),(1)");
+
+ DbTxnManager txnMgr2 = (DbTxnManager)
TxnManagerFactory.getTxnManagerFactory().getTxnManager(conf);
+ swapTxnManager(txnMgr2);
+ // Start a query on driver2
+ driver2.compileAndRespond("update target set i = 1 where i = 1");
+
+ swapTxnManager(txnMgr);
+ // this should cause a conflict which should cause driver2.run to invoke
its conflict lambda
+ driver.run("update target set i = 1 where i = 1");
+ swapTxnManager(txnMgr2);
+
+ // This run should conflict with the above query and cause the "conflict
lambda" to be execute,
+ // which will then also conflict with the driver2 query and cause it to
retry.
+ AtomicInteger conflictCount = new AtomicInteger();
+ driver2.run(() -> {
+ conflictCount.getAndIncrement();
+ // on first conflict,
+ // we execute another query to cause an additional conflict
+ if (conflictCount.get() == 1) {
+ swapTxnManager(txnMgr);
+ // this should cause a conflict
+ try {
+ driver.run("update target set i = 1 where i = 1");
+ } catch (Exception e) {
+ // do nothing
+ }
+ swapTxnManager(txnMgr2);
+ }
+ });
+
+ // we expected two conflicts
+ Assert.assertEquals(2, conflictCount.get());
+ swapTxnManager(txnMgr);
+ // we expect two rows
+ driver.run("select * from target");
+ List<String> res = new ArrayList<>();
+ driver.getFetchTask().fetch(res);
+ Assert.assertEquals(2, res.size());
+ }
+
+ @Rule
+ public ExpectedException exceptionRule = ExpectedException.none();
+
+ @Test
+ public void testConcurrentConflictMaxRetryCount() throws Exception {
+ dropTable(new String[]{"target"});
+
+ driver2.getConf().setBoolVar(HiveConf.ConfVars.TXN_WRITE_X_LOCK, true);
+
+ final int maxRetries = 4;
+
driver2.getConf().setIntVar(HiveConf.ConfVars.HIVE_TXN_MAX_RETRYSNAPSHOT_COUNT,
maxRetries);
+
+ driver.run("create table target(i int) stored as orc tblproperties
('transactional'='true')");
+ driver.run("insert into target values (1),(1)");
+
+ DbTxnManager txnMgr2 = (DbTxnManager)
TxnManagerFactory.getTxnManagerFactory().getTxnManager(conf);
+ swapTxnManager(txnMgr2);
+ // Start a query on driver2, we expect this query to never execute because
of HIVE_TXN_MAX_RETRYSNAPSHOT_COUNT.
+ // We verify that it is never executed by counting the number of rows
returned that have i = 1.
+ driver2.compileAndRespond("update target set i = 2 where i = 1");
+
+ swapTxnManager(txnMgr);
+ // this should cause a conflict which should cause driver2.run to invoke
its conflict lambda
+ driver.run("update target set i = 1 where i = 1");
+ swapTxnManager(txnMgr2);
+
+ // This run should conflict with the above query and cause the "conflict
lambda" to be execute,
+ // which will then also conflict with the driver2 query and cause it to
retry. The intent here is
+ // to cause driver2's query to exceed HIVE_TXN_MAX_RETRYSNAPSHOT_COUNT and
throw exception.
+ AtomicInteger conflictCount = new AtomicInteger();
+ exceptionRule.expect(CommandProcessorException.class);
+ exceptionRule.expectMessage("Operation could not be executed, snapshot was
outdated when locks were acquired.");
+ driver2.run(() -> {
+ conflictCount.getAndIncrement();
+ // on first conflict,
+ // we execute another query to cause an additional conflict
+ if (conflictCount.get() <= maxRetries) {
+ swapTxnManager(txnMgr);
+ // this should cause a conflict
+ try {
+ // we use update here, to force a conflict but not create additional
rows
+ driver.run("update target set i = 1 where i = 1");
+ } catch (Exception e) {
+ // do nothing
+ }
+ swapTxnManager(txnMgr2);
+ }
+ });
+
+ // We expect maxRetries+1 conflicts
Review Comment:
I don't think this gets executed because of the exception rule. I'm going to
rewrite this to not use exception rule and use a try / catch and some asserts.
Issue Time Tracking
-------------------
Worklog Id: (was: 834941)
Time Spent: 20m (was: 10m)
> Transaction conflict retry loop only executes once
> --------------------------------------------------
>
> Key: HIVE-26875
> URL: https://issues.apache.org/jira/browse/HIVE-26875
> Project: Hive
> Issue Type: Bug
> Components: HiveServer2
> Reporter: John Sherman
> Assignee: John Sherman
> Priority: Critical
> Labels: pull-request-available
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Currently the "conflict retry loop" only executes once.
> [https://github.com/apache/hive/blob/ab4c53de82d4aaa33706510441167f2df55df15e/ql/src/java/org/apache/hadoop/hive/ql/Driver.java#L264]
> The intent of this loop is to detect if a conflicting transaction has
> committed while we were waiting to acquire locks. If there is a conflicting
> transaction, it invalidates the snapshot, rolls-back the transaction, opens a
> new transaction and tries to re-acquire locks (and then recompile). It then
> checks again if a conflicting transaction has committed and if so, redoes the
> above steps again, up to HIVE_TXN_MAX_RETRYSNAPSHOT_COUNT times.
> However - isValidTxnState relies on getNonSharedLockedTable():
> [https://github.com/apache/hive/blob/ab4c53de82d4aaa33706510441167f2df55df15e/ql/src/java/org/apache/hadoop/hive/ql/DriverTxnHandler.java#L422]
> which does:
> {code:java}
> private Set<String> getNonSharedLockedTables() {
> if (CollectionUtils.isEmpty(driver.getContext().getHiveLocks())) {
> return Collections.emptySet(); // Nothing to check
> }{code}
> getHiveLocks gets populated by lockAndRespond... HOWEVER -
> compileInternal ends up calling compile which ends up calling
> preparForCompile which ends up calling prepareContext which ends up
> destroying the context with the information lockAndRespond populated. So when
> the loop executes after all of this, it will never detect a 2nd conflict
> because isValidTxnState will always return true (because it thinks there are
> no locked objects).
> This manifests as duplicate records being created during concurrent UPDATEs
> if a transaction get conflicted twice.
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