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  2. IMPALA-6222

Make it easier to root-cause "failed to get minimum memory reservation" error



      A user reported this error message:

       ExecQueryFInstances rpc query_id=c94288312d6d4055:bbfa166500000000 failed: Failed to get minimum memory reservation of 26.69 MB on daemon hodor-030.edh.cloudera.com:22000 for query c94288312d6d4055:bbfa166500000000 because it would exceed an applicable memory limit. Memory is likely oversubscribed. Reducing query concurrency or configuring admission control may help avoid this error. Memory usage:
      Process: Limit=96.00 GB Total=16.54 GB Peak=83.37 GB

      It turns out that a query was using up a lot of reservation, but it wasn't immediately apparent that the process reservation was mostly allocated to that query.

      Process: Limit=96.00 GB Total=12.20 GB Peak=83.37 GB
        Buffer Pool: Free Buffers: Total=208.00 MB
        Buffer Pool: Clean Pages: Total=7.19 GB
        Buffer Pool: Unused Reservation: Total=-76.79 GB
        Free Disk IO Buffers: Total=1.37 GB Peak=1.37 GB
        RequestPool=root.default: Total=76.81 GB Peak=77.56 GB
          Query(464a9afdbf2646cf:d9e2d41100000000): Reservation=76.80 GB ReservationLimit=76.80 GB OtherMemory=6.69 MB Total=76.81 GB Peak=76.93 GB
            Fragment 464a9afdbf2646cf:d9e2d4110000003f: Reservation=76.80 GB OtherMemory=6.69 MB Total=76.81 GB Peak=76.81 GB
              SELECT_NODE (id=3): Total=20.00 KB Peak=9.02 MB
                Exprs: Total=4.00 KB Peak=4.00 KB
              ANALYTIC_EVAL_NODE (id=2): Reservation=4.00 MB OtherMemory=6.64 MB Total=10.64 MB Peak=15.04 MB
                Exprs: Total=4.00 KB Peak=4.00 KB
              SORT_NODE (id=1): Reservation=76.79 GB OtherMemory=16.00 KB Total=76.79 GB Peak=76.80 GB
              EXCHANGE_NODE (id=4): Total=0 Peak=0
              DataStreamRecvr: Total=0 Peak=10.19 MB
              DataStreamSender (dst_id=5): Total=1.48 KB Peak=1.48 KB
              CodeGen: Total=1.68 KB Peak=710.00 KB
            Fragment 464a9afdbf2646cf:d9e2d41100000016: Reservation=0 OtherMemory=0 Total=0 Peak=389.69 MB
              HDFS_SCAN_NODE (id=0): Total=0 Peak=388.54 MB
              DataStreamSender (dst_id=4): Total=0 Peak=1.23 MB
              CodeGen: Total=0 Peak=49.00 KB
        Untracked Memory: Total=3.42 GB

      When a user or admin sees this problem they really want to immediately know:

      • What resource is exhausted (i.e. the process-wide reservation)?
      • Which query(ies) are using it and how do I kill them (i.e. what are the query ids and coordinators of the query).

      We should think through the error messages and diagnostics and improve them.


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              • Assignee:
                bikramjeet.vig Bikramjeet Vig
                tarmstrong Tim Armstrong
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