[IMPALA-9842] TestValidateMetrics.test_metrics_are_zero fails with num-fragments-in-flight not reaching zero

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: Impala 4.0.0
• Fix Version/s: Impala 4.0.0
• Component/s: Backend
• Labels: broken-build flaky
• Target Version: Impala 4.0.0
• Epic Color: ghx-label-1
• Assignee: Joe McDonnell
• Reporter: Joe McDonnell
• Created: 09/Jun/20 01:46
• Updated: 04/Nov/20 03:41
• Resolved: 17/Jun/20 16:40

Description

A couple test runs have failed with TestValidateMetrics.test_metrics_are_zero failure: 

AssertionError: Metric value impala-server.num-fragments-in-flight did not reach value 0 in 60s Dumping impalad debug pages: ...

The memz shows: 

Process: Limit=12.00 GB Total=2.93 GB Peak=138.77 GB
  JVM: max heap size: Total=1.78 GB
  JVM: non-heap committed: Total=211.75 MB
  Buffer Pool: Free Buffers: Total=1.90 MB
  Buffer Pool: Clean Pages: Total=0  
  Buffer Pool: Unused Reservation: Total=-2.00 MB
  Control Service Queue: Limit=50.00 MB Total=0 Peak=16.47 MB
  Data Stream Service Queue: Limit=614.40 MB Total=0 Peak=636.91 MB
  Data Stream Manager Early RPCs: Total=0 Peak=684.53 KB
  TCMalloc Overhead: Total=347.15 MB
  Spill-to-disk temporary compression buffers: Limit=512.00 MB Total=0 Peak=110.43 MB
  RequestPool=root.default: Total=4.02 MB Peak=136.23 GB
    Query(074a86ef88e16768:1a7bf9f400000000): Limit=300.00 MB Reservation=4.00 MB Reserva$
      Fragment 074a86ef88e16768:1a7bf9f400000000: Reservation=4.00 MB OtherMemory=16.00 K$
        HDFS_SCAN_NODE (id=0): Reservation=0 OtherMemory=0 Total=0 Peak=830.00 KB
        PLAN_ROOT_SINK: Reservation=4.00 MB ReservationLimit=100.00 MB OtherMemory=8.00 K$
  RequestPool=fe-eval-exprs: Total=0 Peak=256.00 MB
  RequestPool=root.no-limits: Total=0 Peak=188.88 MB
  Untracked Memory: Total=616.14 MB

Query 074a86ef88e16768:1a7bf9f4 is: 

I0608 19:09:08.410117 25628 Frontend.java:1498] 074a86ef88e16768:1a7bf9f400000000] Analyzing query: select * from functional.alltypes limit 10 db: default

The interesting query options are debug_action and fetch_rows_timeout_ms. These narrow it down to hs2/test_fetch_timeout.py (https://github.com/apache/impala/blob/master/tests/hs2/test_fetch_timeout.py#L207-L215):

  11: debug_action (string) = "CRS_BEFORE_COORD_STARTS:SLEEP@5000",
...
  94: fetch_rows_timeout_ms (i64) = 0,

 It is executing only at the coordinator: 

I0608 19:09:08.430388 25637 scheduler.cc:549] 074a86ef88e16768:1a7bf9f400000000] Exec at coord is true
I0608 19:09:08.430755 25637 admission-controller.cc:1296] 074a86ef88e16768:1a7bf9f400000000] Trying to admit id=074a86ef88e16768:1a7bf9f400000000 in pool_name=root.default executor_group_name=default per_host_mem_estimate=20.00 MB dedicated_coord_mem_estimate=120.00 MB max_requests=-1 (configured statically) max_queued=200 (configured statically) max_mem=29.30 GB (configured statically)
I0608 19:09:08.430793 25637 admission-controller.cc:1308] 074a86ef88e16768:1a7bf9f400000000] Stats: agg_num_running=10, agg_num_queued=0, agg_mem_reserved=3.79 GB,  local_host(local_mem_admitted=4.67 GB, num_admitted_running=10, num_queued=0, backend_mem_reserved=2.24 GB)
I0608 19:09:08.430811 25637 admission-controller.cc:894] 074a86ef88e16768:1a7bf9f400000000] Admitting query id=074a86ef88e16768:1a7bf9f400000000
I0608 19:09:08.430881 25637 debug-util.cc:427] 074a86ef88e16768:1a7bf9f400000000] Debug Action: CRS_BEFORE_COORD_STARTS:SLEEP@5000 sleeping for 5000 ms

 The query starts execution: 

I0608 19:09:13.431097 25637 coordinator.cc:143] 074a86ef88e16768:1a7bf9f400000000] Exec() query_id=074a86ef88e16768:1a7bf9f400000000 stmt=select * from functional.alltypes limit 10
I0608 19:09:13.431520 25637 coordinator.cc:463] 074a86ef88e16768:1a7bf9f400000000] starting execution on 1 backends for query_id=074a86ef88e16768:1a7bf9f400000000
I0608 19:09:13.432674   114 control-service.cc:153] 074a86ef88e16768:1a7bf9f400000000] ExecQueryFInstances(): query_id=074a86ef88e16768:1a7bf9f400000000 coord=f0873f7637c8:22000 #instances=1
...
I0608 19:09:13.433480 25637 coordinator.cc:520] 074a86ef88e16768:1a7bf9f400000000] started execution on 1 backends for query_id=074a86ef88e16768:1a7bf9f400000000
I0608 19:09:13.434790 26254 query-state.cc:756] 074a86ef88e16768:1a7bf9f400000000] Executing instance. instance_id=074a86ef88e16768:1a7bf9f400000000 fragment_idx=0 per_fragment_instance_idx=0 coord_state_idx=0 #in-flight=11

The query is unregistered: 

I0608 19:09:13.448494 25628 impala-server.cc:1173] UnregisterQuery(): query_id=074a86ef88e16768:1a7bf9f400000000
I0608 19:09:13.448557 25628 coordinator.cc:644] ExecState: query id=074a86ef88e16768:1a7bf9f400000000 execution cancelled
I0608 19:09:13.448580 25628 coordinator-backend-state.cc:943] query_id=074a86ef88e16768:1a7bf9f400000000 target backend=172.18.0.4:27000: Sending CancelQueryFInstances rpc
I0608 19:09:13.448971   114 control-service.cc:223] CancelQueryFInstances(): query_id=074a86ef88e16768:1a7bf9f400000000
I0608 19:09:13.448995   114 query-exec-mgr.cc:105] QueryState: query_id=074a86ef88e16768:1a7bf9f400000000 refcnt=4
I0608 19:09:13.449007   114 query-state.cc:782] Cancel: query_id=074a86ef88e16768:1a7bf9f400000000
I0608 19:09:13.449023   114 krpc-data-stream-mgr.cc:337] cancelling active streams for fragment_instance_id=074a86ef88e16768:1a7bf9f400000000
I0608 19:09:13.449226 25628 coordinator.cc:889] CancelBackends() query_id=074a86ef88e16768:1a7bf9f400000000, tried to cancel 1 backends
I0608 19:09:13.449291 25628 coordinator.cc:1225] Release admission control resources for query_id=074a86ef88e16768:1a7bf9f400000000

After that, there are periodic reports coming in for 074a86ef88e16768:1a7bf9f400000000 which all return that it is an invalid query. 

The original query is starts at 19:09:08, while the TestValidateMetrics.test_metrics_are_zero check for remaining fragments is happening over an hour later at 20:14:08.**

Interestingly, this has happened on different runs with the exact same query.