add feature to profile just the block validation

[arvidn]

This exposes what is actually going on while we validate blocks. Sometimes the block validation times are affected by other tasks that hog the CPU, blocking the main co-routine from being scheduled.

Purpose:

When understanding what's causing spikes in block validation times, having a profile focused only on the time of validating the block can be quite helpful, especially when pre_validation nor post_processing takes very long.

It can help identify co-routines that run for too long (i.e. perform expensive work in the main thread), hogging the scheduler and delaying other tasks.

Current Behavior:

The only available profiler is for the whole full node task.

New Behavior:

There's now also a profiler for just block validation. If the validation takes longer than 2 seconds, the profile is saved for later analysis.

Testing Notes:

Example profiles from main.

(parsing the SubEpochChallengeSegments is slow)

(serializing the weight proof is slow)

(parsing BlockRecord is slow)

(sleep(0.01) in a loop is slow)

(merkle root validation and BLS signatures can still be expensive)

(saving peers is slow. This caused an 11.9 seconds block validation)

(request_additions is slow)

[coveralls-official]

Pull Request Test Coverage Report for Build 7376667166

• 11 of 11 (100.0%) changed or added relevant lines in 3 files are covered.
• 16 unchanged lines in 5 files lost coverage.
• Overall coverage increased (+0.09%) to 90.582%

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Files with Coverage Reduction	New Missed Lines	%
tests/core/util/test_lockfile.py	1	91.09%
chia/rpc/rpc_server.py	2	88.05%
chia/full_node/full_node.py	3	85.1%
chia/plotters/madmax.py	3	48.77%
chia/daemon/server.py	7	86.48%

Totals
Change from base Build 7339581890:	0.09%
Covered Lines:	94086
Relevant Lines:	103839

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💛 - Coveralls

[wjblanke]

aok