Files
tasks/service/matching/physical_task_queue_manager_test.go
Shahab TajikandLina Jodoin 7c3db63775 Fix TQ dispatch rate for forwarded polls (#6404)
## What changed?
<!-- Describe what has changed in this PR -->
Fix the condition that checks for forwarded polls when tracking
dispatched tasks. Previously, it was checking if the task is forwarded
instead of checking if the poll is forwarded.

## Why?
<!-- Tell your future self why have you made these changes -->
To calculate dispatch rate correctly.

## How did you test it?
<!-- How have you verified this change? Tested locally? Added a unit
test? Checked in staging env? -->
Improved tests to validate stats for all combinations of poll and task
being forwarded or not in combination with force or allow sync. Total 8
combinations.

## Potential risks
<!-- Assuming the worst case, what can be broken when deploying this
change to production? -->
None.

## Documentation
<!-- Have you made sure this change doesn't falsify anything currently
stated in `docs/`? If significant
new behavior is added, have you described that in `docs/`? -->
None.

## Is hotfix candidate?
<!-- Is this PR a hotfix candidate or does it require a notification to
be sent to the broader community? (Yes/No) -->
No hotfix, but should be patched in 1.25 OSS release.
2024-08-30 12:54:11 -07:00

558 lines
20 KiB
Go

// The MIT License
//
// Copyright (c) 2020 Temporal Technologies Inc. All rights reserved.
//
// Copyright (c) 2020 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package matching
import (
"context"
"math"
"math/rand"
"sync/atomic"
"testing"
"time"
"github.com/golang/mock/gomock"
"github.com/pborman/uuid"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
"go.temporal.io/server/common/metrics/metricstest"
"google.golang.org/protobuf/types/known/timestamppb"
enumspb "go.temporal.io/api/enums/v1"
"go.temporal.io/server/api/matchingservicemock/v1"
persistencespb "go.temporal.io/server/api/persistence/v1"
"go.temporal.io/server/common"
"go.temporal.io/server/common/clock"
"go.temporal.io/server/common/cluster"
"go.temporal.io/server/common/dynamicconfig"
"go.temporal.io/server/common/namespace"
"go.temporal.io/server/common/persistence"
"go.temporal.io/server/common/primitives/timestamp"
"go.temporal.io/server/common/tqid"
"go.temporal.io/server/internal/goro"
)
var rpsInf = math.Inf(1)
const (
defaultNamespaceId = "deadbeef-0000-4567-890a-bcdef0123456"
defaultRootTqID = "tq"
)
type tqmTestOpts struct {
config *Config
dbq *PhysicalTaskQueueKey
matchingClientMock *matchingservicemock.MockMatchingServiceClient
}
func defaultTqmTestOpts(controller *gomock.Controller) *tqmTestOpts {
return &tqmTestOpts{
config: defaultTestConfig(),
dbq: defaultTqId(),
matchingClientMock: matchingservicemock.NewMockMatchingServiceClient(controller),
}
}
type testIDBlockAlloc struct {
rid int64
alloc func() (taskQueueState, error)
}
func (a *testIDBlockAlloc) RangeID() int64 {
return a.rid
}
func (a *testIDBlockAlloc) RenewLease(_ context.Context) (taskQueueState, error) {
s, err := a.alloc()
if err == nil {
a.rid = s.rangeID
}
return s, err
}
func makeTestBlocAlloc(f func() (taskQueueState, error)) taskQueueManagerOpt {
return withIDBlockAllocator(&testIDBlockAlloc{alloc: f})
}
func withIDBlockAllocator(ibl idBlockAllocator) taskQueueManagerOpt {
return func(tqm *physicalTaskQueueManagerImpl) {
tqm.backlogMgr.taskWriter.idAlloc = ibl
}
}
// addTasks is a helper which adds numberOfTasks to a taskTracker
func trackTasksHelper(tr *taskTracker, numberOfTasks int) {
for i := 0; i < numberOfTasks; i++ {
// adding a bunch of tasks
tr.incrementTaskCount()
}
}
func TestAddTasksRate(t *testing.T) {
// define a fake clock and it's time for testing
timeSource := clock.NewEventTimeSource()
currentTime := time.Now()
timeSource.Update(currentTime)
tr := newTaskTracker(timeSource)
// mini windows will have the following format : (start time, end time)
// (0 - 4), (5 - 9), (10 - 14), (15 - 19), (20 - 24), (25 - 29), (30 - 34), ...
// rate should be zero when no time is passed
require.Equal(t, float32(0), tr.rate()) // time: 0
trackTasksHelper(tr, 100)
require.Equal(t, float32(0), tr.rate()) // still zero because no time is passed
// tasks should be placed in the first mini-window
timeSource.Advance(1 * time.Second) // time: 1 second
require.InEpsilon(t, float32(100), tr.rate(), 0.001) // 100 tasks added in 1 second = 100 / 1 = 100
// tasks should be placed in the second mini-window with 6 total seconds elapsed
timeSource.Advance(5 * time.Second)
trackTasksHelper(tr, 200) // time: 6 second
require.InEpsilon(t, float32(50), tr.rate(), 0.001) // (100 + 200) tasks added in 6 seconds = 300/6 = 50
timeSource.Advance(24 * time.Second) // time: 30 second
trackTasksHelper(tr, 300)
require.InEpsilon(t, float32(20), tr.rate(), 0.001) // (100 + 200 + 300) tasks added in (30 + 0 (current window)) seconds = 600/30 = 20
// this should clear out the first mini-window of 100 tasks
timeSource.Advance(5 * time.Second) // time: 35 second
trackTasksHelper(tr, 10)
require.InEpsilon(t, float32(17), tr.rate(), 0.001) // (10 + 200 + 300) tasks added in (30 + 0 (current window)) seconds = 510/30 = 17
// this should clear out the second and third mini-windows
timeSource.Advance(15 * time.Second) // time: 50 second
trackTasksHelper(tr, 10)
require.InEpsilon(t, float32(10.666667), tr.rate(), 0.001) // (10 + 10 + 300) tasks added in (30 + 0 (current window)) seconds = 320/30 = 10.66
// a minute passes and no tasks are added
timeSource.Advance(60 * time.Second)
require.Equal(t, float32(0), tr.rate()) // 0 tasks have been added in the last 30 seconds
}
func TestForeignPartitionOwnerCausesUnload(t *testing.T) {
cfg := NewConfig(dynamicconfig.NewNoopCollection())
cfg.RangeSize = 1 // TaskID block size
var leaseErr error
tqm := mustCreateTestPhysicalTaskQueueManager(t, gomock.NewController(t),
makeTestBlocAlloc(func() (taskQueueState, error) {
return taskQueueState{rangeID: 1}, leaseErr
}))
tqm.Start()
defer tqm.Stop(unloadCauseUnspecified)
// TQM started succesfully with an ID block of size 1. Perform one send
// without a poller to consume the one task ID from the reserved block.
err := tqm.SpoolTask(&persistencespb.TaskInfo{
CreateTime: timestamp.TimePtr(time.Now().UTC()),
})
require.NoError(t, err)
// TQM's ID block should be empty so the next AddTask will trigger an
// attempt to obtain more IDs. This specific error type indicates that
// another service instance has become the owner of the partition
leaseErr = &persistence.ConditionFailedError{Msg: "should kill the tqm"}
err = tqm.SpoolTask(&persistencespb.TaskInfo{
CreateTime: timestamp.TimePtr(time.Now().UTC()),
})
require.NoError(t, err)
}
// TODO: this test probably should go to backlog_manager_test
func TestReaderSignaling(t *testing.T) {
readerNotifications := make(chan struct{}, 1)
clearNotifications := func() {
for len(readerNotifications) > 0 {
<-readerNotifications
}
}
tqm := mustCreateTestPhysicalTaskQueueManager(t, gomock.NewController(t))
// redirect taskReader signals into our local channel
tqm.backlogMgr.taskReader.notifyC = readerNotifications
tqm.Start()
defer tqm.Stop(unloadCauseUnspecified)
// shut down the taskReader so it doesn't steal notifications from us
tqm.backlogMgr.taskReader.gorogrp.Cancel()
tqm.backlogMgr.taskReader.gorogrp.Wait()
clearNotifications()
err := tqm.SpoolTask(&persistencespb.TaskInfo{
CreateTime: timestamp.TimePtr(time.Now().UTC()),
})
require.NoError(t, err)
require.Len(t, readerNotifications, 1,
"Spool task should signal taskReader")
clearNotifications()
poller, _ := runOneShotPoller(context.Background(), tqm)
defer poller.Cancel()
task := newInternalTaskForSyncMatch(&persistencespb.TaskInfo{
CreateTime: timestamp.TimePtr(time.Now().UTC()),
}, nil)
sync, err := tqm.TrySyncMatch(context.TODO(), task)
require.NoError(t, err)
require.True(t, sync)
require.Len(t, readerNotifications, 0,
"Sync match should not signal taskReader")
}
// runOneShotPoller spawns a goroutine to call tqm.PollTask on the provided tqm.
// The second return value is a channel of either error or *internalTask.
func runOneShotPoller(ctx context.Context, tqm physicalTaskQueueManager) (*goro.Handle, chan interface{}) {
out := make(chan interface{}, 1)
handle := goro.NewHandle(ctx).Go(func(ctx context.Context) error {
task, err := tqm.PollTask(ctx, &pollMetadata{ratePerSecond: &rpsInf})
if task == nil {
out <- err
return nil
}
task.finish(err)
out <- task
return nil
})
// tqm.PollTask() needs some time to attach the goro started above to the
// internal task channel. Sorry for this but it appears unavoidable.
time.Sleep(10 * time.Millisecond)
return handle, out
}
func defaultTqId() *PhysicalTaskQueueKey {
return newTestUnversionedPhysicalQueueKey(defaultNamespaceId, defaultRootTqID, enumspb.TASK_QUEUE_TYPE_WORKFLOW, 0)
}
func mustCreateTestPhysicalTaskQueueManager(
t *testing.T,
controller *gomock.Controller,
opts ...taskQueueManagerOpt,
) *physicalTaskQueueManagerImpl {
t.Helper()
return mustCreateTestTaskQueueManagerWithConfig(t, controller, defaultTqmTestOpts(controller), opts...)
}
func mustCreateTestTaskQueueManagerWithConfig(
t *testing.T,
controller *gomock.Controller,
testOpts *tqmTestOpts,
opts ...taskQueueManagerOpt,
) *physicalTaskQueueManagerImpl {
t.Helper()
tqm, err := createTestTaskQueueManagerWithConfig(controller, testOpts, opts...)
require.NoError(t, err)
return tqm
}
func createTestTaskQueueManagerWithConfig(
controller *gomock.Controller,
testOpts *tqmTestOpts,
opts ...taskQueueManagerOpt,
) (*physicalTaskQueueManagerImpl, error) {
nsName := namespace.Name("ns-name")
ns, registry := createMockNamespaceCache(controller, nsName)
me := createTestMatchingEngine(controller, testOpts.config, testOpts.matchingClientMock, registry)
me.metricsHandler = metricstest.NewCaptureHandler()
partition := testOpts.dbq.Partition()
tqConfig := newTaskQueueConfig(partition.TaskQueue(), me.config, nsName)
userDataManager := newUserDataManager(me.taskManager, me.matchingRawClient, partition, tqConfig, me.logger, me.namespaceRegistry)
pm := createTestTaskQueuePartitionManager(ns, partition, tqConfig, me, userDataManager)
tlMgr, err := newPhysicalTaskQueueManager(pm, testOpts.dbq, opts...)
pm.defaultQueue = tlMgr
if err != nil {
return nil, err
}
return tlMgr, nil
}
func createTestTaskQueuePartitionManager(ns *namespace.Namespace, partition tqid.Partition, tqConfig *taskQueueConfig, me *matchingEngineImpl, userDataManager userDataManager) *taskQueuePartitionManagerImpl {
pm := &taskQueuePartitionManagerImpl{
engine: me,
partition: partition,
config: tqConfig,
ns: ns,
logger: me.logger,
matchingClient: me.matchingRawClient,
metricsHandler: me.metricsHandler,
userDataManager: userDataManager,
}
me.partitions[partition.Key()] = pm
return pm
}
func TestReaderBacklogAge(t *testing.T) {
controller := gomock.NewController(t)
// Create queue Manager and set queue state
tlm := mustCreateTestPhysicalTaskQueueManager(t, controller)
tlm.backlogMgr.db.rangeID = int64(1)
tlm.backlogMgr.db.ackLevel = int64(0)
tlm.backlogMgr.taskAckManager.setAckLevel(tlm.backlogMgr.db.ackLevel)
tlm.backlogMgr.taskReader.taskBuffer <- randomTaskInfoWithAgeTaskID(time.Minute, 1)
tlm.backlogMgr.taskReader.taskBuffer <- randomTaskInfoWithAgeTaskID(10*time.Second, 2)
tlm.backlogMgr.taskReader.gorogrp.Go(tlm.backlogMgr.taskReader.dispatchBufferedTasks)
require.EventuallyWithT(t, func(collect *assert.CollectT) {
assert.InDelta(t, time.Minute, tlm.backlogMgr.taskReader.getBacklogHeadAge(), float64(time.Second))
}, time.Second, 10*time.Millisecond)
_, err := tlm.backlogMgr.pqMgr.PollTask(context.Background(), &pollMetadata{ratePerSecond: &rpsInf})
require.NoError(t, err)
require.EventuallyWithT(t, func(collect *assert.CollectT) {
assert.InDelta(t, 10*time.Second, tlm.backlogMgr.taskReader.getBacklogHeadAge(), float64(500*time.Millisecond))
}, time.Second, 10*time.Millisecond)
_, err = tlm.backlogMgr.pqMgr.PollTask(context.Background(), &pollMetadata{ratePerSecond: &rpsInf})
require.NoError(t, err)
require.EventuallyWithT(t, func(collect *assert.CollectT) {
assert.Equalf(t, time.Duration(0), tlm.backlogMgr.taskReader.getBacklogHeadAge(), "backlog age being reset because of no tasks in the buffer")
}, time.Second, 10*time.Millisecond)
}
func randomTaskInfoWithAgeTaskID(age time.Duration, TaskID int64) *persistencespb.AllocatedTaskInfo {
rt1 := time.Now().Add(-age)
rt2 := rt1.Add(time.Hour)
return &persistencespb.AllocatedTaskInfo{
Data: &persistencespb.TaskInfo{
NamespaceId: uuid.New(),
WorkflowId: uuid.New(),
RunId: uuid.New(),
ScheduledEventId: rand.Int63(),
CreateTime: timestamppb.New(rt1),
ExpiryTime: timestamppb.New(rt2),
},
TaskId: TaskID,
}
}
func TestLegacyDescribeTaskQueue(t *testing.T) {
controller := gomock.NewController(t)
defer controller.Finish()
startTaskID := int64(1)
taskCount := int64(3)
PollerIdentity := "test-poll"
// Create queue Manager and set queue state
tlm := mustCreateTestPhysicalTaskQueueManager(t, controller)
tlm.backlogMgr.db.rangeID = int64(1)
tlm.backlogMgr.db.ackLevel = int64(0)
tlm.backlogMgr.taskAckManager.setAckLevel(tlm.backlogMgr.db.ackLevel)
for i := int64(0); i < taskCount; i++ {
tlm.backlogMgr.taskAckManager.addTask(startTaskID + i)
}
// Manually increase the backlog counter since it does not get incremented by taskAckManager.addTask
// Only doing this for the purpose of this test
tlm.backlogMgr.db.updateApproximateBacklogCount(taskCount)
includeTaskStatus := false
descResp := tlm.LegacyDescribeTaskQueue(includeTaskStatus)
require.Equal(t, 0, len(descResp.DescResponse.GetPollers()))
require.Nil(t, descResp.DescResponse.GetTaskQueueStatus())
includeTaskStatus = true
taskQueueStatus := tlm.LegacyDescribeTaskQueue(includeTaskStatus).DescResponse.GetTaskQueueStatus()
require.NotNil(t, taskQueueStatus)
require.Zero(t, taskQueueStatus.GetAckLevel())
require.Equal(t, taskCount, taskQueueStatus.GetReadLevel())
require.Equal(t, taskCount, taskQueueStatus.GetBacklogCountHint())
taskIDBlock := taskQueueStatus.GetTaskIdBlock()
require.Equal(t, int64(1), taskIDBlock.GetStartId())
require.Equal(t, tlm.config.RangeSize, taskIDBlock.GetEndId())
// Add a poller and complete all tasks
tlm.pollerHistory.updatePollerInfo(pollerIdentity(PollerIdentity), &pollMetadata{})
for i := int64(0); i < taskCount; i++ {
tlm.backlogMgr.taskAckManager.completeTask(startTaskID + i)
}
descResp = tlm.LegacyDescribeTaskQueue(includeTaskStatus)
require.Equal(t, 1, len(descResp.DescResponse.GetPollers()))
require.Equal(t, PollerIdentity, descResp.DescResponse.Pollers[0].GetIdentity())
require.NotEmpty(t, descResp.DescResponse.Pollers[0].GetLastAccessTime())
rps := 5.0
tlm.pollerHistory.updatePollerInfo(pollerIdentity(PollerIdentity), &pollMetadata{ratePerSecond: &rps})
descResp = tlm.LegacyDescribeTaskQueue(includeTaskStatus)
require.Equal(t, 1, len(descResp.DescResponse.GetPollers()))
require.Equal(t, PollerIdentity, descResp.DescResponse.Pollers[0].GetIdentity())
require.True(t, descResp.DescResponse.Pollers[0].GetRatePerSecond() > 4.0 && descResp.DescResponse.Pollers[0].GetRatePerSecond() < 6.0)
taskQueueStatus = descResp.DescResponse.GetTaskQueueStatus()
require.NotNil(t, taskQueueStatus)
require.Equal(t, taskCount, taskQueueStatus.GetAckLevel())
require.Zero(t, taskQueueStatus.GetBacklogCountHint()) // should be 0 since AckManager.CompleteTask decrements the updated backlog counter
}
func TestCheckIdleTaskQueue(t *testing.T) {
controller := gomock.NewController(t)
defer controller.Finish()
cfg := NewConfig(dynamicconfig.NewNoopCollection())
cfg.MaxTaskQueueIdleTime = dynamicconfig.GetDurationPropertyFnFilteredByTaskQueue(2 * time.Second)
tqCfg := defaultTqmTestOpts(controller)
tqCfg.config = cfg
// Idle
tlm := mustCreateTestTaskQueueManagerWithConfig(t, controller, tqCfg)
tlm.Start()
time.Sleep(1 * time.Second)
require.Equal(t, common.DaemonStatusStarted, atomic.LoadInt32(&tlm.status))
// Active poll-er
tlm = mustCreateTestTaskQueueManagerWithConfig(t, controller, tqCfg)
tlm.Start()
tlm.pollerHistory.updatePollerInfo("test-poll", &pollMetadata{})
require.Equal(t, 1, len(tlm.GetAllPollerInfo()))
time.Sleep(1 * time.Second)
require.Equal(t, common.DaemonStatusStarted, atomic.LoadInt32(&tlm.status))
tlm.Stop(unloadCauseUnspecified)
require.Equal(t, common.DaemonStatusStopped, atomic.LoadInt32(&tlm.status))
// Active adding task
tlm = mustCreateTestTaskQueueManagerWithConfig(t, controller, tqCfg)
tlm.Start()
require.Equal(t, 0, len(tlm.GetAllPollerInfo()))
tlm.backlogMgr.taskReader.Signal()
time.Sleep(1 * time.Second)
require.Equal(t, common.DaemonStatusStarted, atomic.LoadInt32(&tlm.status))
tlm.Stop(unloadCauseUnspecified)
require.Equal(t, common.DaemonStatusStopped, atomic.LoadInt32(&tlm.status))
}
func TestAddTaskStandby(t *testing.T) {
controller := gomock.NewController(t)
defer controller.Finish()
tlm := mustCreateTestTaskQueueManagerWithConfig(
t,
controller,
defaultTqmTestOpts(controller),
func(tqm *physicalTaskQueueManagerImpl) {
ns := namespace.NewGlobalNamespaceForTest(
&persistencespb.NamespaceInfo{},
&persistencespb.NamespaceConfig{},
&persistencespb.NamespaceReplicationConfig{
ActiveClusterName: cluster.TestAlternativeClusterName,
},
cluster.TestAlternativeClusterInitialFailoverVersion,
)
// we need to override the mockNamespaceCache to return a passive namespace
mockNamespaceCache := namespace.NewMockRegistry(controller)
mockNamespaceCache.EXPECT().GetNamespaceByID(gomock.Any()).Return(ns, nil).AnyTimes()
mockNamespaceCache.EXPECT().GetNamespaceName(gomock.Any()).Return(ns.Name(), nil).AnyTimes()
tqm.namespaceRegistry = mockNamespaceCache
},
)
tlm.Start()
// stop taskWriter so that we can check if there's any call to it
// otherwise the task persist process is async and hard to test
tlm.backlogMgr.taskWriter.Stop()
<-tlm.backlogMgr.taskWriter.writeLoop.Done()
err := tlm.SpoolTask(&persistencespb.TaskInfo{
CreateTime: timestamp.TimePtr(time.Now().UTC()),
})
require.Equal(t, errShutdown, err) // task writer was stopped above
}
func TestTQMDoesFinalUpdateOnIdleUnload(t *testing.T) {
t.Parallel()
controller := gomock.NewController(t)
cfg := NewConfig(dynamicconfig.NewNoopCollection())
cfg.MaxTaskQueueIdleTime = dynamicconfig.GetDurationPropertyFnFilteredByTaskQueue(1 * time.Second)
tqCfg := defaultTqmTestOpts(controller)
tqCfg.config = cfg
tqm := mustCreateTestTaskQueueManagerWithConfig(t, controller, tqCfg)
tm, ok := tqm.partitionMgr.engine.taskManager.(*testTaskManager)
require.True(t, ok)
tqm.Start()
time.Sleep(2 * time.Second) // will unload due to idleness
require.Equal(t, 1, tm.getUpdateCount(tqCfg.dbq))
}
func TestTQMDoesNotDoFinalUpdateOnOwnershipLost(t *testing.T) {
// TODO: use mocks instead of testTaskManager so we can do synchronization better instead of sleeps
t.Parallel()
controller := gomock.NewController(t)
cfg := NewConfig(dynamicconfig.NewNoopCollection())
cfg.UpdateAckInterval = dynamicconfig.GetDurationPropertyFnFilteredByTaskQueue(2 * time.Second)
tqCfg := defaultTqmTestOpts(controller)
tqCfg.config = cfg
tqm := mustCreateTestTaskQueueManagerWithConfig(t, controller, tqCfg)
tm, ok := tqm.partitionMgr.engine.taskManager.(*testTaskManager)
require.True(t, ok)
tqm.Start()
time.Sleep(1 * time.Second)
// simulate ownership lost
ttm := tm.getQueueManager(tqCfg.dbq)
ttm.Lock()
ttm.rangeID++
ttm.Unlock()
time.Sleep(2 * time.Second) // will attempt to update and fail and not try again
require.Equal(t, 1, tm.getUpdateCount(tqCfg.dbq))
}
func TestTQMInterruptsPollOnClose(t *testing.T) {
t.Parallel()
controller := gomock.NewController(t)
tqm := mustCreateTestPhysicalTaskQueueManager(t, controller)
tqm.Start()
pollStart := time.Now()
pollCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
_, pollCh := runOneShotPoller(pollCtx, tqm)
tqm.Stop(unloadCauseUnspecified) // should interrupt poller
<-pollCh
require.Less(t, time.Since(pollStart), 4*time.Second)
}