otel.process.context_switches metric counts only the context switches of the main thread #36804
Description
Component(s)
receiver/hostmetrics
What happened?
Description
The otel.process.context_switches metric claims to count context switches for a given process. It obtains the number of context switches from /proc/<pid>/status (through https://github.com/shirou/gopsutil). Unfortunately, this file counts only the context switches of the lead thread on Linux. Calling it the context switches of the process is hence misleading.
Steps to Reproduce
Log into a Linux machine, find a process with multiple threads, and compare the context-switch count. It can happen that a thread has more context switches than the process context-switch count. Example:
cat /proc/4491/status /proc/4491/task/4491/status /proc/4491/task/4495/status | grep nonvoluntary
nonvoluntary_ctxt_switches: 9
nonvoluntary_ctxt_switches: 9
nonvoluntary_ctxt_switches: 139
Expected Result
Either the metric should note that is is correct only for single-threaded processes, or the scraper should go through all threads within the same process and sum up their individual context switches
Actual Result
The metric reports the context switches of the lead thread as if they were the context switches of the entire process
Collector version
0.110.0
Environment information
Environment
OS: Ubuntu 20.04
Compiler(if manually compiled):
OpenTelemetry Collector configuration
No response
Log output
No response
Additional context
No response