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https://issues.apache.org/jira/browse/DRILL-5963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16287564#comment-16287564
]
ASF GitHub Bot commented on DRILL-5963:
---------------------------------------
Github user arina-ielchiieva commented on a diff in the pull request:
https://github.com/apache/drill/pull/1051#discussion_r156358222
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/work/foreman/Foreman.java ---
@@ -502,33 +438,82 @@ private void runFragment(List<PlanFragment>
fragmentsList) throws ExecutionSetup
}
}
+ assert rootFragment != null;
+
final FragmentRoot rootOperator;
try {
rootOperator =
drillbitContext.getPlanReader().readFragmentRoot(rootFragment.getFragmentJson());
} catch (IOException e) {
throw new ExecutionSetupException(String.format("Unable to parse
FragmentRoot from fragment: %s", rootFragment.getFragmentJson()));
}
queryRM.setCost(rootOperator.getCost());
- admit(null);
- drillbitContext.getWorkBus().addFragmentStatusListener(queryId,
queryManager.getFragmentStatusListener());
-
drillbitContext.getClusterCoordinator().addDrillbitStatusListener(queryManager.getDrillbitStatusListener());
- logger.debug("Submitting fragments to run.");
+ fragmentsRunner.setFragmentsInfo(planFragments, rootFragment,
rootOperator);
- // set up the root fragment first so we'll have incoming buffers
available.
- setupRootFragment(rootFragment, rootOperator);
+ startQueryProcessing();
+ }
- setupNonRootFragments(planFragments);
+ /**
+ * Enqueues the query and once enqueued, starts sending out query
fragments for further execution.
+ * Moves query to RUNNING state.
+ */
+ private void startQueryProcessing() {
+ enqueue();
+ runFragments();
+ queryStateProcessor.moveToState(QueryState.RUNNING, null);
+ }
- moveToState(QueryState.RUNNING, null);
- logger.debug("Fragments running.");
+ /**
+ * Move query to ENQUEUED state. Enqueues query if queueing is enabled.
+ * Foreman run will be blocked until query is enqueued.
+ * In case of failures (ex: queue timeout exception) will move query to
FAILED state.
+ */
+ private void enqueue() {
+ queryStateProcessor.moveToState(QueryState.ENQUEUED, null);
+
+ try {
+ queryRM.admit();
+ queryStateProcessor.moveToState(QueryState.STARTING, null);
+ } catch (QueueTimeoutException | QueryQueueException e) {
+ queryStateProcessor.moveToState(QueryState.FAILED, e);
+ } finally {
+ String queueName = queryRM.queueName();
+ queryManager.setQueueName(queueName == null ? "Unknown" : queueName);
--- End diff --
@paul-rogers `QueryStateProcessor` is responsible to enforcing valid state
transitions (directly if fragments were not sent out yet) or though queuing (if
fragments were sent out), proper cancelling and failing, Also it is responsible
for query counters. `Foreman` is responsible for execution part and does all
the work. If we move remaining logic from `Foreman` into
`QueryStateProcessor`, we'll end up with the same huge unreadable class as
`Foreman` was before. At this point of refactoring, I suggest we stop and if
further refactoring is needed, create new Jira.
> Canceling a query hung in planning state, leaves the query in ENQUEUED state
> for ever.
> --------------------------------------------------------------------------------------
>
> Key: DRILL-5963
> URL: https://issues.apache.org/jira/browse/DRILL-5963
> Project: Apache Drill
> Issue Type: Bug
> Components: Execution - Flow
> Affects Versions: 1.12.0
> Environment: Drill 1.12.0-SNAPSHOT, commit:
> 4a718a0bd728ae02b502ac93620d132f0f6e1b6c
> Reporter: Khurram Faraaz
> Assignee: Arina Ielchiieva
> Priority: Critical
> Fix For: 1.13.0
>
> Attachments: enqueued-2.png
>
>
> Canceling the below query that is hung in planning state, leaves the query in
> ENQUEUED state for ever.
> Here is the query that is hung in planning state
> {noformat}
> 0: jdbc:drill:schema=dfs.tmp> select 1 || ',' || 2 || ',' || 3 || ',' || 4 ||
> ',' || 5 || ',' || 6 || ',' || 7 || ',' || 8 || ',' || 9 || ',' || 0 || ','
> AS CSV_DATA from (values(1));
> +--+
> | |
> +--+
> +--+
> No rows selected (304.291 seconds)
> {noformat}
> Explain plan for that query also just hangs.
> {noformat}
> explain plan for select 1 || ',' || 2 || ',' || 3 || ',' || 4 || ',' || 5 ||
> ',' || 6 || ',' || 7 || ',' || 8 || ',' || 9 || ',' || 0 || ',' AS CSV_DATA
> from (values(1));
> ...
> {noformat}
> The above issues show the following problems:
> *1. Simple query with reasonable number of concat functions hangs.*
> In reality query does not hang it just take lots of time to execute. The root
> cause is that during planning time DrillFuncHolderExpr return type is
> extensively used to determine matching function, matching type etc. Though
> this type is retrieved via
> [getter|https://github.com/apache/drill/blob/master/exec/java-exec/src/main/java/org/apache/drill/exec/expr/DrillFuncHolderExpr.java#L41]
> in reality complex logic is executed beaneath it. For example for [concat
> function|https://github.com/apache/drill/blob/master/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/output/ConcatReturnTypeInference.java#L47].
> Since function return type can not be changes during DrillFuncHolderExpr
> life time, it is safe to cache it.
> *2. No mechanism to cancel query during ENQUEUED state.*
> Currently Drill does not have mechanism to cancel query before STARTING /
> RUNNING states. Plus ENQUEUED state includes two PLANNING and ENQUEUED.
> Also submitting mechanism for submitting query to the queue is blocking,
> making foreman wait till enqueueing is done Making it non-blocking will
> prevent consuming threads that just sit idle in a busy system and also is
> important when we move to a real admission control solution.
> The following changes were made to address above issues:
> a. two new states were added: PREPARING (when foreman is initialized) and
> PLANNING (includes logical and / or physical planning).
> b. process of query enqueuing was made non-blocking. Once query was enqueued,
> fragments runner is called to submit fragments locally and remotely.
> c. ability to cancel query during planning and enqueued states was added.
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