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  1. Java Mission Control
  2. JMC-7932

Incorrect "Free Physical Memory" reported

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    • x86_64
    • os_x

    Description

      ADDITIONAL SYSTEM INFORMATION :
      MacBook Pro with 64GB of memory
      Mac OS X 12.6
      Java 11 and 20-ea

      A DESCRIPTION OF THE PROBLEM :
      JMC reports "Free Physical Memory"

      The maximum amount of used memory was 97 % of the physical memory available.
      The maximum amount of memory used was 62,1 GiB. This is 97 % of the 64 GiB of physical memory available. Having little free memory may lead to swapping, which is very expensive. To avoid this, either decrease the memory usage or increase the amount of available memory.

      However, this does not correlate with the results of top:

      Processes: 648 total, 3 running, 645 sleeping, 3358 threads 22:50:53
      Load Avg: 1.63, 2.46, 2.81 CPU usage: 4.35% user, 1.54% sys, 94.10% idle SharedLibs: 741M resident, 116M data, 47M linkedit.
      MemRegions: 505833 total, 16G resident, 321M private, 3583M shared. PhysMem: 38G used (4587M wired), 26G unused.
      VM: 55T vsize, 3152M framework vsize, 1313336(0) swapins, 1390271(0) swapouts. Networks: packets: 32927070/30G in, 32681859/30G out.
      Disks: 6888226/134G read, 7090535/143G written.

      It also does not correlate with the OperatingSystem MBean:

      Name Value Type Display Name Update Interval Description
      PhysicalMemoryUsagePercent 0.5973562598228455 Percentage Used Physical Memory (%) -1 The amount, measured in percentage, of physical memory that is used by the JVM.

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      Start a profile with a MacBook Pro 64GB of memory, see the warning every time of "Free Physical Memory"

      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      This should not have been reported as an issue.
      ACTUAL -
      "Free Physical Memory"

      The maximum amount of used memory was 97 % of the physical memory available.
      The maximum amount of memory used was 62,1 GiB. This is 97 % of the 64 GiB of physical memory available. Having little free memory may lead to swapping, which is very expensive. To avoid this, either decrease the memory usage or increase the amount of available memory.

      CUSTOMER SUBMITTED WORKAROUND :
      Workaround is to ignore that warning.

      FREQUENCY : always

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            webbuggrp Webbug Group
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            Dates

              Created:
              Updated: