Uploaded image for project: 'Core Server'
  1. Core Server
  2. SERVER-60412

Host memory limit check does not honor cgroups v2

    XMLWordPrintableJSON

Details

    • Fully Compatible
    • ALL
    • v5.0, v4.4, v4.2
    • Service Arch 2022-1-24
    • 2

    Description

      As I checked mongoDB gained support for memory constraints over cgroup in linux with SERVER-16571. However it seems that it doesn't have the ability to check memory limit if host is using cgroups v2 resulting hostInfo.system.memLimitMB to be equal to system memory in a containerized environment.

      Current code to read memory limits in src/mongo/util/processinfo_linux.cpp

      // LinuxSysHelper::getMemorySizeLimit().
      .....
      std::string cgmemlimit = readLineFromFile("/sys/fs/cgroup/memory/memory.limit_in_bytes");
      ....

      But in cgroups v2 the memory limit is at /sys/fs/cgroup/memory.max.

      I think engine should check if the cgroups v2 is enabled on the host and then read the limits according to that.

      Tested on mongodb 4.2.6 in docker containers at host Fedore CoreOS 34.20210904.3.0. But I do believe newer versions have the same since source code seems same since first implementation.

       

      Attachments

        Issue Links

          Activity

            People

              amirsaman.memaripour@mongodb.com Amirsaman Memaripour
              ayhanap@gmail.com Ayhan APAYDIN
              Votes:
              2 Vote for this issue
              Watchers:
              16 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved: