OCPBUGS-17157: opm: always serve pprof endpoints, improve server allocations

[stevekuznetsov]

There's no substantial runtime cost to serving the endpoints by default, and when things hit the fan you always need to query them in situ.

Description of the change:

Motivation for the change:

Reviewer Checklist

• Implementation matches the proposed design, or proposal is updated to match implementation
• Sufficient unit test coverage
• Sufficient end-to-end test coverage
• Docs updated or added to /docs
• Commit messages sensible and descriptive

[codecov]

Codecov Report

Merging #1129 (c2e5511) into master (bca2bfb) will increase coverage by 0.04%.
Report is 1 commits behind head on master.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master    #1129      +/-   ##
==========================================
+ Coverage   53.77%   53.81%   +0.04%     
==========================================
  Files         108      108              
  Lines       10163    10166       +3     
==========================================
+ Hits         5465     5471       +6     
+ Misses       3738     3734       -4     
- Partials      960      961       +1     

Files Changed	Coverage Δ
pkg/cache/json.go	57.02% <33.33%> (+0.35%)	⬆️
pkg/cache/tar.go	63.15% <66.66%> (+2.04%)	⬆️

... and 2 files with indirect coverage changes

[stevekuznetsov]

Note on the first commit: io.Copy will allocate the exact same size buffer (buf := make([]byte, 32*1024)) for each file, as long as the file is larger than the buffer, which almost all are. In the catalog I am looking at, there are 1703 files on disk and I saw ~50MiB allocated at startup. Doing the math and looking at pprof, that's the clear culprit. While this is un-used memory, it will take a long time for the kernel to reclaim it from Go's runtime and there's no need to do the allocations. Each file is read in serially, so using a singular buffer should not impact how long it takes to run this check at startup.

[stevekuznetsov]

unit tests broken on codecov ...

[2023-07-27T14:38:37.937Z] ['error'] There was an error running the uploader: Error uploading to [https://codecov.io:](https://codecov.io/) Error: There was an error fetching the storage URL during POST: 404 - {'detail': ErrorDetail(string='Unable to locate build via Github Actions API. Please upload with the Codecov repository upload token to resolve issue.', code='not_found')}
Error: Codecov: Failed to properly upload: The process '/home/runner/work/_actions/codecov/codecov-action/v3/dist/codecov' failed with exit code 255

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: grokspawn, stevekuznetsov

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[grokspawn]

/lgtm

[openshift-ci-robot]

@stevekuznetsov: Jira Issue OCPBUGS-17157: Some pull requests linked via external trackers have merged:

The following pull requests linked via external trackers have not merged:

• openshift/operator-framework-olm#526 is open

These pull request must merge or be unlinked from the Jira bug in order for it to move to the next state. Once unlinked, request a bug refresh with /jira refresh.

Jira Issue OCPBUGS-17157 has not been moved to the MODIFIED state.

In response to this:

There's no substantial runtime cost to serving the endpoints by default, and when things hit the fan you always need to query them in situ.

Description of the change:

Motivation for the change:

Reviewer Checklist

• Implementation matches the proposed design, or proposal is updated to match implementation
• Sufficient unit test coverage
• Sufficient end-to-end test coverage
• Docs updated or added to /docs
• Commit messages sensible and descriptive

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