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https://issues.apache.org/jira/browse/DRILL-5963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16267632#comment-16267632
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ASF GitHub Bot commented on DRILL-5963:
---------------------------------------
Github user ppadma commented on a diff in the pull request:
https://github.com/apache/drill/pull/1051#discussion_r153285121
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/work/foreman/Foreman.java ---
@@ -256,12 +239,14 @@ public void run() {
// track how long the query takes
queryManager.markStartTime();
- enqueuedQueries.dec();
runningQueries.inc();
+ queryText = queryRequest.getPlan();
+ recordNewState(QueryState.PLANNING);
--- End diff --
why this code is moved out of the try block ? I believe getPlan can throw
an exception which we should handle. Also, should this be handled under
moveToState ?
> 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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