owner: fix cleanup stale tasks before capture info is constructed (#1269

) (#1280)

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

cdc/owner.go

@@ -20,6 +20,7 @@ import (
 	"math"
 	"os"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/pingcap/errors"
@@ -68,7 +69,8 @@ type Owner struct {
 	pdClient    pd.Client
 	etcdClient  kv.CDCEtcdClient
 
-	captures map[model.CaptureID]*model.CaptureInfo
+	captureLoaded int32
+	captures      map[model.CaptureID]*model.CaptureInfo
 
 	adminJobs     []model.AdminJob
 	adminJobsLock sync.Mutex
@@ -1116,6 +1118,12 @@ func (o *Owner) watchFeedChange(ctx context.Context) {
 }
 
 func (o *Owner) run(ctx context.Context) error {
+	// captureLoaded == 0 means capture information is not built, owner can't
+	// run normal jobs now.
+	if atomic.LoadInt32(&o.captureLoaded) == int32(0) {
+		return nil
+	}
+
 	o.l.Lock()
 	defer o.l.Unlock()
 
@@ -1373,6 +1381,15 @@ func (o *Owner) rebuildCaptureEvents(ctx context.Context, captures map[model.Cap
 			o.removeCapture(c)
 		}
 	}
+	// captureLoaded is used to check whether the owner can execute cleanup stale tasks job.
+	// Because at the very beginning of a new owner, it doesn't have capture information in
+	// memory, cleanup stale tasks could have a false positive (where positive means owner
+	// should cleanup the stale task of a specific capture). After the first time of capture
+	// rebuild, even the etcd compaction and watch capture is rerun, we don't need to check
+	// captureLoaded anymore because existing tasks must belong to a capture which is still
+	// maintained in owner's memory.
+	atomic.StoreInt32(&o.captureLoaded, 1)
+
 	// clean up stale tasks each time before watch capture event starts,
 	// for two reasons:
 	// 1. when a new owner is elected, it must clean up stale task status and positions.

cdc/owner_test.go

@@ -18,6 +18,7 @@ import (
 	"fmt"
 	"net/url"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/google/uuid"
@@ -906,13 +907,24 @@ func (s *ownerSuite) TestCleanUpStaleTasks(c *check.C) {
 			orphanTables: make(map[model.TableID]model.Ts),
 		},
 	}
+
+	// capture information is not built, owner.run does nothing
+	err = owner.run(ctx)
+	c.Assert(err, check.IsNil)
+	statuses, err := s.client.GetAllTaskStatus(ctx, changefeed)
+	c.Assert(err, check.IsNil)
+	// stale tasks are not cleaned up, since `cleanUpStaleTasks` does not run
+	c.Assert(len(statuses), check.Equals, 2)
+	c.Assert(len(owner.captures), check.Equals, 0)
+
 	err = owner.rebuildCaptureEvents(ctx, captures)
 	c.Assert(err, check.IsNil)
 	c.Assert(len(owner.captures), check.Equals, 1)
 	c.Assert(owner.captures, check.HasKey, capture.info.ID)
+	c.Assert(atomic.LoadInt32(&owner.captureLoaded), check.Equals, int32(1))
 	c.Assert(owner.changeFeeds[changefeed].orphanTables, check.DeepEquals, map[model.TableID]model.Ts{51: 100})
 	// check stale tasks are cleaned up
-	statuses, err := s.client.GetAllTaskStatus(ctx, changefeed)
+	statuses, err = s.client.GetAllTaskStatus(ctx, changefeed)
 	c.Assert(err, check.IsNil)
 	c.Assert(len(statuses), check.Equals, 1)
 	c.Assert(statuses, check.HasKey, capture.info.ID)