RFR: 8321931: memory_swap_current_in_bytes reports 0 as "unlimited"

[Gerard Ziemski]

We make a distinction between 0 for a limit vs non-limit cgroup values.

For a limit-type value, 0 means `unlimited`. For all the others 0 means simply 0.

Output before from `jcmd PID VM.info`:


container (cgroup) information:
container_type: cgroupv2
cpu_cpuset_cpus: not supported
cpu_memory_nodes: not supported
active_processor_count: 8
cpu_quota: not supported
cpu_period: not supported
cpu_shares: not supported
memory_limit_in_bytes: unlimited
memory_and_swap_limit_in_bytes: unlimited
memory_soft_limit_in_bytes: unlimited
memory_usage_in_bytes: 11129120 k
memory_max_usage_in_bytes: not supported
memory_swap_current_in_bytes: unlimited
memory_swap_max_limit_in_bytes: unlimited
maximum number of tasks: 18963
current number of tasks: 33


Output now from `jcmd PID VM.info`:


container (cgroup) information:
container_type: cgroupv2
cpu_cpuset_cpus: not supported
cpu_memory_nodes: not supported
active_processor_count: 8
cpu_quota: not supported
cpu_period: not supported
cpu_shares: not supported
memory_limit_in_bytes: unlimited
memory_and_swap_limit_in_bytes: unlimited
memory_soft_limit_in_bytes: unlimited
memory_usage_in_bytes: 4962584 k
memory_max_usage_in_bytes: not supported
memory_swap_current_in_bytes: 0
memory_swap_max_limit_in_bytes: unlimited
maximum number of tasks: 18963
current number of tasks: 33

-------------

Commit messages:
 - distinquish between 0 and unlimited

Changes: https://git.openjdk.org/jdk/pull/17314/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17314&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8321931
  Stats: 8 lines in 5 files changed: 0 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/17314.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17314/head:pull/17314

PR: https://git.openjdk.org/jdk/pull/17314