No goroutines:
BenchmarkBuild_SimpleTest/few_texts,_lot_identical_words-4 10 100572572 ns/op
BenchmarkBuild_SimpleTest/few_texts,_lot_different_words-4 4 306221418 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_lot_identical_words-4 5 205309372 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_lot_different_words-4 2 595846354 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_few_identical_words-4 5 217976917 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_few_different_words-4 4 293552779 ns/op
Goroutines for each text with mutexes:
BenchmarkBuild_SimpleTest/few_texts,_lot_identical_words-4 7 146568713 ns/op
BenchmarkBuild_SimpleTest/few_texts,_lot_different_words-4 4 317066828 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_lot_identical_words-4 3 447675132 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_lot_different_words-4 1 1550963764 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_few_identical_words-4 2 535026034 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_few_different_words-4 2 778628443 ns/op
Goroutines for each text with merging:
BenchmarkBuild_SimpleTest/few_texts,_lot_identical_words-4 24 47877207 ns/op
BenchmarkBuild_SimpleTest/few_texts,_lot_different_words-4 2 633592157 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_lot_identical_words-4 8 128835411 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_lot_different_words-4 1 1343868627 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_few_identical_words-4 2 631027274 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_few_different_words-4 2 572615981 ns/op
Goroutines for each text with straight-forward merging:
BenchmarkBuild_SimpleTest/few_texts,_lot_identical_words-4 21 49184865 ns/op
BenchmarkBuild_SimpleTest/few_texts,_lot_different_words-4 2 603161220 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_lot_identical_words-4 8 130800840 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_lot_different_words-4 1 1415940423 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_few_identical_words-4 2 586184468 ns/op
BenchmarkBuild_SimpleTest/lot_texts,_few_different_words-4 2 588764880 ns/op
No goroutines
BenchmarkIndex_Find/lot_texts,_few_words,_100-words_phrase-4 123 9972986 ns/op
BenchmarkIndex_Find/lot_texts,_few_words,_500-words_phrase-4 24 49493559 ns/op
BenchmarkIndex_Find/few_texts,_lot_words,_100-words_phrase-4 9 122293310 ns/op
BenchmarkIndex_Find/few_texts,_lot_words,_500-words_phrase-4 2 606485413 ns/op
With goroutines
BenchmarkIndex_Find/lot_texts,_few_words,_100-words_phrase-4 43 27244357 ns/op
BenchmarkIndex_Find/lot_texts,_few_words,_500-words_phrase-4 10 110494054 ns/op
BenchmarkIndex_Find/few_texts,_lot_words,_100-words_phrase-4 4 317114024 ns/op
BenchmarkIndex_Find/few_texts,_lot_words,_500-words_phrase-4 1 1335210932 ns/op
No goroutines
BenchmarkGetTextsAndTitlesFromFiles/read_a_lot_of_small_files-4 14 77076962 ns/op
BenchmarkGetTextsAndTitlesFromFiles/read_a_few_of_large_files-4 655 1772980 ns/op
With goroutines
BenchmarkGetTextsAndTitlesFromDir/read_a_lot_of_small_files-4 20 55243215 ns/op
BenchmarkGetTextsAndTitlesFromDir/read_a_few_of_large_files-4 694 1723631 ns/op