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fix: storage/remote.pool interned refs count and flaky test (#16335)

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* Fix storage/remote.pool interned refs count and flaky test

I saw TestIntern_MultiRef_Concurrent failing on a different PR saying 'expected refs to be 1 but it was 2'.

I took a look, and it definitely can be racy, especially with a time.Sleep() of just 1ms.

I'm fixing that by explicitly waiting until it has been released, and by repeating that 1000 times, otherwise it's just a recipe for a future flaky test.

OTOH, I also took a look at the implementation and saw that we were not holding the RLock() when increasing the references count, so when releasing there was a race condition for the cleanup, I fixed that by holding RLock() while increasing the references count.

Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>

* s/Equalf/Equal/

Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>

---------

Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
This commit is contained in:
Oleg Zaytsev 2025-03-27 21:04:30 +01:00 committed by GitHub
parent 7d73c1d3f8
commit c5b92f71d4
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GPG Key ID: B5690EEEBB952194
2 changed files with 16 additions and 9 deletions
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6
storage/remote/intern.go
View File

@ -61,11 +61,15 @@ func (p *pool) intern(s string) string {
p.mtx.RLock()
interned, ok := p.pool[s]
p.mtx.RUnlock()
if ok {
// Increase the reference count while we're still holding the read lock,
// This will prevent the release() from deleting the entry while we're increasing its ref count.
interned.refs.Inc()
p.mtx.RUnlock()
return interned.s
}
p.mtx.RUnlock()
p.mtx.Lock()
defer p.mtx.Unlock()
if interned, ok := p.pool[s]; ok {

19
storage/remote/intern_test.go
View File

@ -20,7 +20,6 @@ package remote
import (
"testing"
"time"
"github.com/stretchr/testify/require"
)
@ -74,17 +73,21 @@ func TestIntern_MultiRef_Concurrent(t *testing.T) {
interner.intern(testString)
interned, ok := interner.pool[testString]
require.True(t, ok)
require.Equalf(t, int64(1), interned.refs.Load(), "expected refs to be 1 but it was %d", interned.refs.Load())
require.Equal(t, int64(1), interned.refs.Load(), "wrong interned refs count")
go interner.release(testString)
interner.intern(testString)
time.Sleep(time.Millisecond)
for i := 0; i < 1000; i++ {
released := make(chan struct{})
go func() {
interner.release(testString)
close(released)
}()
interner.intern(testString)
<-released
}
interner.mtx.RLock()
interned, ok = interner.pool[testString]
interner.mtx.RUnlock()
require.True(t, ok)
require.Equalf(t, int64(1), interned.refs.Load(), "expected refs to be 1 but it was %d", interned.refs.Load())
require.Equal(t, int64(1), interned.refs.Load(), "wrong interned refs count")
}