config: validate DeadlockHistoryCapacity config item

config/config.go

@@ -524,6 +524,14 @@ func DefaultPessimisticTxn() PessimisticTxn {
 	}
 }
 
+// Valid validates the configuration for PessimisticTxn config.
+func (cfg *PessimisticTxn) Valid() error {
+	if cfg.DeadlockHistoryCapacity > 10000 {
+		return fmt.Errorf("pessimistic-txn.deadlock-history-capacity can not be larger than 10000")
+	}
+	return nil
+}
+
 // Plugin is the config for plugin
 type Plugin struct {
 	Dir  string `toml:"dir" json:"dir"`
@@ -900,6 +908,10 @@ func (c *Config) Valid() error {
 		return err
 	}
 
+	if err := c.PessimisticTxn.Valid(); err != nil {
+		return err
+	}
+
 	if c.Performance.TxnTotalSizeLimit > 1<<40 {
 		return fmt.Errorf("txn-total-size-limit should be less than %d", 1<<40)
 	}

config/config_test.go

@@ -462,6 +462,25 @@ func TestOOMActionValid(t *testing.T) {
 	}
 }
 
+func TestPessimisticTxnValid(t *testing.T) {
+	t.Parallel()
+
+	c1 := NewConfig()
+	tests := []struct {
+		pessimisticTxn PessimisticTxn
+		valid          bool
+	}{
+		{PessimisticTxn{DeadlockHistoryCapacity: 10}, true},
+		{PessimisticTxn{DeadlockHistoryCapacity: 0}, true},
+		{PessimisticTxn{DeadlockHistoryCapacity: 10000}, true},
+		{PessimisticTxn{DeadlockHistoryCapacity: 10001}, false},
+	}
+	for _, tt := range tests {
+		c1.PessimisticTxn = tt.pessimisticTxn
+		require.Equal(t, tt.valid, c1.Valid() == nil)
+	}
+}
+
 func TestTxnTotalSizeLimitValid(t *testing.T) {
 	t.Parallel()