[instrumentation-system-metrics] add support for pypy3

[codeboten]

Some of the metrics gathered in opentelemetry-instrumentation-system-metrics are different in pypy3. For example, the following method fails on pypy3:

module 'gc' has no attribute 'get_count'

Instead, getting counts for garbage collection is done via GC hooks. See the following for more details:
https://doc.pypy.org/en/latest/gc_info.html

The work in this issue is to make the instrumentation either produce all the same metrics or exclude the instruments that don't have equivalents. Ideally at the end of this issue, the tests for this instrumentation library will be enabled in tox for pypy3.

[rahuldimri]

@codeboten Can I work on this ? if this feature not yet implemented.

[rahulhacker]

@srikanthccv can you please assign this to me, as we made some progress on this issue.

[rahulhacker]

@srikanthccv can you please assign this to me, as we made some progress on this issue.

[rahulhacker]

@srikanthccv
Approach:
We implemented the changes in the init.py file in the function def _get_runtime_gc_count
Handled the Cpython and PyPy using platform package, for PyPy we used GCHooks class) as mentioned in the document to achieve the gc.gc_count of Cpython in PyPy and same code running in the Cpython. Will raise the PR in some days along with the test cases, just want to confirm if we are in the right path.

Below are the sample output we are getting for PyPy3.

Note: Going to create a new file or include in the same file GCHooks Class as mentioned in above link, in order to get the objects for gc in PyPy

[ocelotl]

@srikanthccv Approach: We implemented the changes in the init.py file in the function def _get_runtime_gc_count Handled the Cpython and PyPy using platform package, for PyPy we used GCHooks class) as mentioned in the document to achieve the gc.gc_count of Cpython in PyPy and same code running in the Cpython. Will raise the PR in some days along with the test cases, just want to confirm if we are in the right path.

Below are the sample output we are getting for PyPy3.

Note: Going to create a new file or include in the same file GCHooks Class as mentioned in above link, in order to get the objects for gc in PyPy

Out of curiosity, @rahulhacker, how did you implement the hook for gc_count?