Improve Contest Estimator performance #1659

[Markoutte]

Description

Use non-blocking job.join instead of spinlock for waiting until subjob is done (fixes #1659). Also, do not force reloading soot, because it takes budget time as much as 1 initialization does.

Fixes #1659

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Manual Scenario

Run the example from the issue. It generates tests with coverage > 50%.

<StatsForClass(com.google.common.primitives.Shorts)> :
	canceled by timeout = true
	#methods = 49, 
	#methods started symbolic exploration = 49
	#methods with at least one TC = 24
	#methods with exceptions = 0
	#generated TC = 175
	#total coverage = 505/891
	#fuzzed coverage = 505/891
	#concolic coverage = 0/891

Also, profiler's result is much clearer:

Test generation with only `forceSootReload = false` optimization

<StatsForClass(com.google.common.primitives.Shorts)> :
	canceled by timeout = true
	#methods = 49, 
	#methods started symbolic exploration = 49
	#methods with at least one TC = 20
	#methods with exceptions = 0
	#generated TC = 90
	#total coverage = 464/891
	#fuzzed coverage = 464/891
	#concolic coverage = 0/891

Test generation with only `job.join` optimization

<StatsForClass(com.google.common.primitives.Shorts)> :
	canceled by timeout = true
	#methods = 49, 
	#methods started symbolic exploration = 49
	#methods with at least one TC = 23
	#methods with exceptions = 0
	#generated TC = 165
	#total coverage = 487/891
	#fuzzed coverage = 487/891
	#concolic coverage = 0/891

Checklist:

• The change followed the style guidelines of the UTBot project
• Self-review of the code is passed
• The change contains enough commentaries, particularly in hard-to-understand areas
• New documentation is provided or existed one is altered
• No new warnings
• New tests have been added
• All tests pass locally with my changes