Fixed go test -race -bench=. . when running in parallel systems to prevent data races

[Aniruddhraam]

Fix data races in benchmark test suite when running with -race

Summary

Fixes data races flagged when running go test -race -bench=. in bigcache_bench_test.go.

Root Cause & Changes

1. Moved b.ReportAllocs() outside b.RunParallel

   • b.ReportAllocs() mutates non-thread-safe internal fields on *testing.B.
   • Calling b.ReportAllocs() inside b.RunParallel(...) caused concurrent write data races on *testing.B across parallel worker goroutines.
   • Fix: Relocated b.ReportAllocs() to the benchmark setup phase outside b.RunParallel across writeToCache, appendToCache, readFromCache, readFromCacheNonExistentKeys, and BenchmarkIterateOverCache.

2. Isolated EntryInfoIterator instances per worker goroutine

   • EntryInfoIterator is a stateful cursor. While SetNext() locks internal state during element advancement, it releases the lock before returning, allowing Value() to read state without holding the lock.
   • Sharing a single Iterator instance across multiple parallel goroutines inside b.RunParallel caused data races between concurrent SetNext() writes and Value() reads.
   • Fix: Moved it := cache.Iterator() inside the b.RunParallel loop so each worker goroutine operates on its own iterator instance, and added a documentation comment explaining iterator thread isolation.

Verification

Ran benchmarks with the Go race detector enabled:

go test -race -bench=. .

[cristaloleg]

SGTM