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  2. IMPALA-9754

buffer_pool_limit error message is confusing



    • Improvement
    • Status: Resolved
    • Minor
    • Resolution: Fixed
    • None
    • Impala 4.0.0
    • Backend
    • ghx-label-4


      The error message for an invalid value of buffer_pool_limit is confusing. For example:

      I0515 18:30:20.143811     1 exec-env.cc:480] System memory available: 30.63 GB (from physical mem)
      I0515 18:30:20.144037     1 exec-env.cc:487] CGroup memory limit for this process reduces physical memory available to: 9.31 GB
      I0515 18:30:20.144050     1 exec-env.cc:503] Using process memory limit: 7.45 GB (--mem_limit=80% of 9.31 GB)
      I0515 18:30:20.150154     1 status.cc:129] Invalid --buffer_pool_limit value, must be a percentage or positive bytes value or percentage: 85%
          @           0xc33b79
          @          0x111afb8
          @          0x1251256
          @           0xb730b3
          @     0x7f60da4c9554
          @           0xbf3e86
      F0515 18:30:20.150177     1 impalad-main.cc:73] Invalid --buffer_pool_limit value, must be a percentage or positive bytes value or percentage: 85%
      . Impalad exiting. 

      1: "must be a percentage or positive bytes value or percentage" needs to be revised to something like "must be a positive bytes value or percentage"
      2: The error message makes it sound like the value of 85% is invalid, when in reality, it is a valid value - Impala does some internal calculations of what the actual buffer_pool_limit should be internally (see ExecEnv::Init) - these calculations first compute the mem limit for the process (ChooseProcessMemLimit) based on the physical machines memory + cgroup settings, and then if mem_limit_includes_jvm == true it subtracts the value of Xmx from the amount of available memory - we don't have logic to capture if the results of that subtraction becomes a negative number, which causes the buffer_pool_limit parsing to fail in a weird way. We should add a check to see if admit_mem_limit_ -= JvmMemoryMetric::HEAP_MAX_USAGE->GetValue() is negative, and then exit with an informative status message




            sql_forever Qifan Chen
            stakiar Sahil Takiar
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