Support process shared memory monitoring

[SilenceAdele]

• Upgrade procfs from v0.14.0 to v0.17.0 to support shared memory collection for process.
• Implement process shared memory monitoring logic.

[SilenceAdele]

/cc @SuperQ @ncabatoff

[SilenceAdele]

Hi, long time no see @SuperQ @ncabatoff
The PR adding support for process shared memory monitoring in process-exporter has been submitted for quite some time. Below is a summary of my investigation and testing results for this PR. I’d appreciate it if you could help review it. If there are any questions or further concerns, please feel free to reach out to me at any time.

• Summary of Process Memory Metrics in the master branch of process-exporter（Excluding shared memory）
  

Serial Number	Related Linux process memory parameters	The corresponding file in Linux
1	RSS	/proc/[pid]/stat
2	VSize	/proc/[pid]/stat
3	VmSwap	/proc/[pid]/status
4	Pss	/proc/[pid]/smaps_rollup
5	SwapPss	/proc/[pid]/smaps_rollup

• Data sources for process shared memory: /proc/[pid]/status vs /proc/[pid]/statm

1. The proc_pid_statm(5) documentation defines the shared field as the number of shared memory pages.
2. It further indicates that shared memory can be approximated using RssFile + RssShmem from /proc/[pid]/status, while explicitly warning that these values are not accurate.
3. If an accurate calculation of process shared memory size is required, it should be derived from the shared field in /proc/[pid]/statm.

• Summary of Process Memory Metrics from /proc/[pid]/statm in procfs
  Related PR: Supports collection of process shared memory prometheus/procfs#719 [Merged in procfs v0.17.0]
  

Serial Number	Related Linux process memory parameters	Remark
1	Size
2	Resident
3	Shared	Used to monitor process shared memory.
4	Text
5	Lib
6	Data
7	Dt

• Upgrading procfs from v0.14.0 to v0.17.0 is theoretically assessed to have no impact on the functionality implemented on the process-exporter. The related procfs module changes mainly include bug fixes, new features, and code optimizations.
  

procfs patch	process-exporter refer procfs module	Remark
v0.15.0 bugfix: s/TrimRight/TrimSuffix for certain cases by rexagod · Pull Request #618 · prometheus/procfs · GitHub	cmdline	bugfix
v0.17.0 Parse StartCode, EndCode, and StartStack in Proc.Stat() by pgimalac · Pull Request #659 · prometheus/procfs · GitHub	proc_stat	feature
v0.16.0 Fix parsing NSpids field in /proc/{PID}/status by timuralp · Pull Request #648 · prometheus/procfs · GitHub	proc_status	bugfix
	proc_cgroup
	proc_io
v0.17.0 Supports collection of process shared memory by SilenceAdele · Pull Request #719 · prometheus/procfs · GitHub	proc_statm	feature
	proc_limits
v0.16.0 Forbid print statements by SuperQ · Pull Request #668 · prometheus/procfs · GitHub	proc_smaps	perf
	fileDescriptors
	Wchan

• A comparison of the metrics output between the master branch and the 321 branch(My PR) of process-exporter shows that the only difference lies in the namedprocess_namegroup_memory_bytes metric, where the 321 branch introduces an additional entry that includes process shared memory. This is consistent with the expected behavior.

# matcher config
process_names:
  - name: "{{.Comm}}-{{.PID}}"
    comm:
      - node

# start command
 go run cmd/process-exporter/main.go -config.path=../conf  --children=false

• The process shared memory reported by process-exporter matches the values reported by the top command, as expected.

• Based on the above analysis and testing, process-exporter was upgraded to use procfs from v0.14.0 to v0.17.0:

1. Process-exporter did not exhibit any compatibility issues in its use of procfs after the upgrade.
2. The newly introduced Shared field from /proc/[pid]/statm in procfs can be used to implement process shared memory metrics.

[SilenceAdele]

ping......