executor: avoid concurrently update for SimpleLRUCache in `ApplyCac…

…he` (#50356) (#50385)

close #50347

executor/apply_cache.go

@@ -66,6 +66,12 @@ func (c *applyCache) put(key applyCacheKey, val kvcache.Value) {
  c.cache.Put(key, val)
 }
 
+func (c *applyCache) removeOldest() (kvcache.Key, kvcache.Value, bool) {
+ c.lock.Lock()
+ defer c.lock.Unlock()
+ return c.cache.RemoveOldest()
+}
+
 // Get gets a cache item according to cache key. It's thread-safe.
 func (c *applyCache) Get(key applyCacheKey) (*chunk.List, error) {
  value, hit := c.get(key)
@@ -83,7 +89,7 @@ func (c *applyCache) Set(key applyCacheKey, value *chunk.List) (bool, error) {
  return false, nil
  }
  for mem+c.memTracker.BytesConsumed() > c.memCapacity {
- evictedKey, evictedValue, evicted := c.cache.RemoveOldest()
+ evictedKey, evictedValue, evicted := c.removeOldest()
  if !evicted {
  return false, nil
  }

executor/apply_cache_test.go

@@ -17,6 +17,7 @@ package executor
 import (
  "strconv"
  "strings"
+ "sync"
  "testing"
 
  "github.com/pingcap/tidb/parser/mysql"
@@ -77,3 +78,61 @@ func TestApplyCache(t *testing.T) {
  require.NoError(t, err)
  require.Nil(t, result)
 }
+
+func TestApplyCacheConcurrent(t *testing.T) {
+ ctx := mock.NewContext()
+ ctx.GetSessionVars().MemQuotaApplyCache = 100
+ applyCache, err := newApplyCache(ctx)
+ require.NoError(t, err)
+
+ fields := []*types.FieldType{types.NewFieldType(mysql.TypeLonglong)}
+ value := make([]*chunk.List, 2)
+ key := make([][]byte, 2)
+ for i := 0; i < 2; i++ {
+ value[i] = chunk.NewList(fields, 1, 1)
+ srcChunk := chunk.NewChunkWithCapacity(fields, 1)
+ srcChunk.AppendInt64(0, int64(i))
+ srcRow := srcChunk.GetRow(0)
+ value[i].AppendRow(srcRow)
+ key[i] = []byte(strings.Repeat(strconv.Itoa(i), 100))
+
+ // TODO: *chunk.List.GetMemTracker().BytesConsumed() is not accurate, fix it later.
+ require.Equal(t, int64(100), applyCacheKVMem(key[i], value[i]))
+ }
+
+ applyCache.Set(key[0], value[0])
+ var wg sync.WaitGroup
+ wg.Add(2)
+ var func1 = func() {
+ for i := 0; i < 100; i++ {
+ for {
+ result, err := applyCache.Get(key[0])
+ require.NoError(t, err)
+ if result != nil {
+ applyCache.Set(key[1], value[1])
+ break
+ }
+ }
+ }
+ wg.Done()
+ }
+ var func2 = func() {
+ for i := 0; i < 100; i++ {
+ for {
+ result, err := applyCache.Get(key[1])
+ require.NoError(t, err)
+ if result != nil {
+ applyCache.Set(key[0], value[0])
+ break
+ }
+ }
+ }
+ wg.Done()
+ }
+ go func1()
+ go func2()
+ wg.Wait()
+ result, err := applyCache.Get(key[0])
+ require.NoError(t, err)
+ require.NotNil(t, result)
+}