diff options
Diffstat (limited to 'src/weak/pointer_test.go')
| -rw-r--r-- | src/weak/pointer_test.go | 40 |
1 files changed, 38 insertions, 2 deletions
diff --git a/src/weak/pointer_test.go b/src/weak/pointer_test.go index da464a8d01..5e8b9bef58 100644 --- a/src/weak/pointer_test.go +++ b/src/weak/pointer_test.go @@ -16,8 +16,10 @@ import ( ) type T struct { - // N.B. This must contain a pointer, otherwise the weak handle might get placed - // in a tiny block making the tests in this package flaky. + // N.B. T is what it is to avoid having test values get tiny-allocated + // in the same block as the weak handle, but since the fix to + // go.dev/issue/76007, this should no longer be possible. + // TODO(mknyszek): Consider using tiny-allocated values for all the tests. t *T a int b int @@ -327,3 +329,37 @@ func TestImmortalPointer(t *testing.T) { t.Errorf("immortal weak pointer to %p has unexpected Value %p", want, got) } } + +func TestPointerTiny(t *testing.T) { + runtime.GC() // Clear tiny-alloc caches. + + const N = 1000 + wps := make([]weak.Pointer[int], N) + for i := range N { + // N.B. *x is just an int, so the value is very likely + // tiny-allocated alongside the weak handle, assuming bug + // from go.dev/issue/76007 exists. + x := new(int) + *x = i + wps[i] = weak.Make(x) + } + + // Get the cleanups to start running. + runtime.GC() + + // Expect at least 3/4ths of the weak pointers to have gone nil. + // + // Note that we provide some leeway since it's possible our allocation + // gets grouped with some other long-lived tiny allocation, but this + // shouldn't be the case for the vast majority of allocations. + n := 0 + for _, wp := range wps { + if wp.Value() == nil { + n++ + } + } + const want = 3 * N / 4 + if n < want { + t.Fatalf("not enough weak pointers are nil: expected at least %v, got %v", want, n) + } +} |