gc_worker: enable green GC by default (#18167)

Signed-off-by: youjiali1995 <zlwgx1023@gmail.com> Co-authored-by: ti-srebot <66930949+ti-srebot@users.noreply.github.com> Co-authored-by: Shirly <wuxuelian@pingcap.com>
pingcap · Jun 27, 2020 · 43d7b0e · 43d7b0e
1 parent 773b291
commit 43d7b0e
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Showing 2 changed files with 13 additions and 9 deletions.
diff --git a/store/tikv/gcworker/gc_worker.go b/store/tikv/gcworker/gc_worker.go
@@ -135,7 +135,7 @@ const (
 	gcScanLockModeKey      = "tikv_gc_scan_lock_mode"
 	gcScanLockModeLegacy   = "legacy"
 	gcScanLockModePhysical = "physical"
-	gcScanLockModeDefault  = gcScanLockModeLegacy
+	gcScanLockModeDefault  = gcScanLockModePhysical
 
 	gcAutoConcurrencyKey     = "tikv_gc_auto_concurrency"
 	gcDefaultAutoConcurrency = true
@@ -157,6 +157,7 @@ var gcVariableComments = map[string]string{
 	gcEnableKey:          "Current GC enable status",
 	gcModeKey:            "Mode of GC, \"central\" or \"distributed\"",
 	gcAutoConcurrencyKey: "Let TiDB pick the concurrency automatically. If set false, tikv_gc_concurrency will be used",
+	gcScanLockModeKey:    "Mode of scanning locks, \"physical\" or \"legacy\"",
 }
 
 func (w *GCWorker) start(ctx context.Context, wg *sync.WaitGroup) {
@@ -914,7 +915,10 @@ func (w *GCWorker) checkUsePhysicalScanLock() (bool, error) {
 		return false, errors.Trace(err)
 	}
 	if str == "" {
-		// Do not save it here, so that this config is hidden.
+		err = w.saveValueToSysTable(gcScanLockModeKey, gcScanLockModeDefault)
+		if err != nil {
+			return false, errors.Trace(err)
+		}
 		str = gcScanLockModeDefault
 	}
 	if strings.EqualFold(str, gcScanLockModePhysical) {

diff --git a/store/tikv/gcworker/gc_worker_test.go b/store/tikv/gcworker/gc_worker_test.go
@@ -481,23 +481,23 @@ func (s *testGCWorkerSuite) TestCheckGCMode(c *C) {
 func (s *testGCWorkerSuite) TestCheckScanLockMode(c *C) {
 	usePhysical, err := s.gcWorker.checkUsePhysicalScanLock()
 	c.Assert(err, IsNil)
-	c.Assert(usePhysical, Equals, false)
-	// This is a hidden config, so default value will not be inserted to table.
+	c.Assert(usePhysical, Equals, gcScanLockModeDefault == gcScanLockModePhysical)
+	// Now the row must be set to the default value.
 	str, err := s.gcWorker.loadValueFromSysTable(gcScanLockModeKey)
 	c.Assert(err, IsNil)
-	c.Assert(str, Equals, "")
+	c.Assert(str, Equals, gcScanLockModeDefault)
 
-	err = s.gcWorker.saveValueToSysTable(gcScanLockModeKey, gcScanLockModePhysical)
+	err = s.gcWorker.saveValueToSysTable(gcScanLockModeKey, gcScanLockModeLegacy)
 	c.Assert(err, IsNil)
 	usePhysical, err = s.gcWorker.checkUsePhysicalScanLock()
 	c.Assert(err, IsNil)
-	c.Assert(usePhysical, Equals, true)
+	c.Assert(usePhysical, Equals, false)
 
-	err = s.gcWorker.saveValueToSysTable(gcScanLockModeKey, gcScanLockModeLegacy)
+	err = s.gcWorker.saveValueToSysTable(gcScanLockModeKey, gcScanLockModePhysical)
 	c.Assert(err, IsNil)
 	usePhysical, err = s.gcWorker.checkUsePhysicalScanLock()
 	c.Assert(err, IsNil)
-	c.Assert(usePhysical, Equals, false)
+	c.Assert(usePhysical, Equals, true)
 
 	err = s.gcWorker.saveValueToSysTable(gcScanLockModeKey, "invalid_mode")
 	c.Assert(err, IsNil)