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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_r153333422 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/work/foreman/rm/ThrottledResourceManager.java --- @@ -288,8 +287,10 @@ public void setCost(double cost) { } @Override - public void admit() throws QueueTimeoutException, QueryQueueException { - lease = rm.queue().enqueue(foreman.getQueryId(), queryCost); + public void admit() { + QueueAcquirer queueAcquirer = new QueueAcquirer(rm.queue(), foreman, queryCost); + queueAcquirerThread = new Thread(queueAcquirer); --- End diff -- General comment about the approach. We create minimum 2 threads for any query. With this, when queuing is enabled, we are creating minimum three threads. Instead, when a query is cancelled, is it possible to interrupt the foreman thread itself if that is blocked ? > 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. -- This message was sent by Atlassian JIRA (v6.4.14#64029)