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Merge pull request #1199 from hashicorp/f-lighter-blocked-evals 

Reuse blocked evaluations and handle unblock events that occurred during scheduling
This commit is contained in:
Alex Dadgar 2016-05-25 11:17:59 -07:00
parent 5b1a2100c6 6a236872b4
commit 52a78c5930
15 changed files with 815 additions and 26 deletions
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119
nomad/blocked_evals.go
View File

@ -35,15 +35,21 @@ type BlockedEvals struct {
escaped map[string]*structs.Evaluation
// unblockCh is used to buffer unblocking of evaluations.
capacityChangeCh chan string
capacityChangeCh chan *capacityUpdate
// jobs is the map of blocked job and is used to ensure that only one
// blocked eval exists for each job.
jobs map[string]struct{}
// unblockIndexes maps computed node classes to the index in which they were
// unblocked. This is used to check if an evaluation could have been
// unblocked between the time they were in the scheduler and the time they
// are being blocked.
unblockIndexes map[string]uint64
// duplicates is the set of evaluations for jobs that had pre-existing
// blocked evaluations. These should be marked as cancelled since only one
// blocked eval is neeeded bper job.
// blocked eval is neeeded per job.
duplicates []*structs.Evaluation
// duplicateCh is used to signal that a duplicate eval was added to the
@ -55,6 +61,12 @@ type BlockedEvals struct {
stopCh chan struct{}
}
// capacityUpdate stores unblock data.
type capacityUpdate struct {
computedClass string
index uint64
}
// BlockedStats returns all the stats about the blocked eval tracker.
type BlockedStats struct {
// TotalEscaped is the total number of blocked evaluations that have escaped
@ -73,7 +85,8 @@ func NewBlockedEvals(evalBroker *EvalBroker) *BlockedEvals {
captured: make(map[string]*structs.Evaluation),
escaped: make(map[string]*structs.Evaluation),
jobs: make(map[string]struct{}),
capacityChangeCh: make(chan string, unblockBuffer),
unblockIndexes: make(map[string]uint64),
capacityChangeCh: make(chan *capacityUpdate, unblockBuffer),
duplicateCh: make(chan struct{}, 1),
stopCh: make(chan struct{}),
stats: new(BlockedStats),
@ -133,6 +146,16 @@ func (b *BlockedEvals) Block(eval *structs.Evaluation) {
return
}
// Check if the eval missed an unblock while it was in the scheduler at an
// older index. The scheduler could have been invoked with a snapshot of
// state that was prior to additional capacity being added or allocations
// becoming terminal.
if b.missedUnblock(eval) {
// Just re-enqueue the eval immediately
b.evalBroker.Enqueue(eval)
return
}
// Mark the job as tracked.
b.stats.TotalBlocked++
b.jobs[eval.JobID] = struct{}{}
@ -152,16 +175,65 @@ func (b *BlockedEvals) Block(eval *structs.Evaluation) {
b.captured[eval.ID] = eval
}
// missedUnblock returns whether an evaluation missed an unblock while it was in
// the scheduler. Since the scheduler can operate at an index in the past, the
// evaluation may have been processed missing data that would allow it to
// complete. This method returns if that is the case and should be called with
// the lock held.
func (b *BlockedEvals) missedUnblock(eval *structs.Evaluation) bool {
var max uint64 = 0
for class, index := range b.unblockIndexes {
// Calculate the max unblock index
if max < index {
max = index
}
elig, ok := eval.ClassEligibility[class]
if !ok {
// The evaluation was processed and did not encounter this class.
// Thus for correctness we need to unblock it.
return true
}
// The evaluation could use the computed node class and the eval was
// processed before the last unblock.
if elig && eval.SnapshotIndex < index {
return true
}
}
// If the evaluation has escaped, and the map contains an index older than
// the evaluations, it should be unblocked.
if eval.EscapedComputedClass && eval.SnapshotIndex < max {
return true
}
// The evaluation is ahead of all recent unblocks.
return false
}
// Unblock causes any evaluation that could potentially make progress on a
// capacity change on the passed computed node class to be enqueued into the
// eval broker.
func (b *BlockedEvals) Unblock(computedClass string) {
func (b *BlockedEvals) Unblock(computedClass string, index uint64) {
b.l.Lock()
// Do nothing if not enabled
if !b.enabled {
b.l.Unlock()
return
}
b.capacityChangeCh <- computedClass
// Store the index in which the unblock happened. We use this on subsequent
// block calls in case the evaluation was in the scheduler when a trigger
// occured.
b.unblockIndexes[computedClass] = index
b.l.Unlock()
b.capacityChangeCh <- &capacityUpdate{
computedClass: computedClass,
index: index,
}
}
// watchCapacity is a long lived function that watches for capacity changes in
@ -171,15 +243,15 @@ func (b *BlockedEvals) watchCapacity() {
select {
case <-b.stopCh:
return
case computedClass := <-b.capacityChangeCh:
b.unblock(computedClass)
case update := <-b.capacityChangeCh:
b.unblock(update.computedClass, update.index)
}
}
}
// unblock unblocks all blocked evals that could run on the passed computed node
// class.
func (b *BlockedEvals) unblock(computedClass string) {
func (b *BlockedEvals) unblock(computedClass string, index uint64) {
b.l.Lock()
defer b.l.Unlock()
@ -229,6 +301,35 @@ func (b *BlockedEvals) unblock(computedClass string) {
}
}
// UnblockFailed unblocks all blocked evaluation that were due to scheduler
// failure.
func (b *BlockedEvals) UnblockFailed() {
b.l.Lock()
defer b.l.Unlock()
// Do nothing if not enabled
if !b.enabled {
return
}
var unblock []*structs.Evaluation
for id, eval := range b.captured {
if eval.TriggeredBy == structs.EvalTriggerMaxPlans {
unblock = append(unblock, eval)
delete(b.captured, id)
}
}
for id, eval := range b.escaped {
if eval.TriggeredBy == structs.EvalTriggerMaxPlans {
unblock = append(unblock, eval)
delete(b.escaped, id)
}
}
b.evalBroker.EnqueueAll(unblock)
}
// GetDuplicates returns all the duplicate evaluations and blocks until the
// passed timeout.
func (b *BlockedEvals) GetDuplicates(timeout time.Duration) []*structs.Evaluation {
@ -273,7 +374,7 @@ func (b *BlockedEvals) Flush() {
b.escaped = make(map[string]*structs.Evaluation)
b.jobs = make(map[string]struct{})
b.duplicates = nil
b.capacityChangeCh = make(chan string, unblockBuffer)
b.capacityChangeCh = make(chan *capacityUpdate, unblockBuffer)
b.stopCh = make(chan struct{})
b.duplicateCh = make(chan struct{}, 1)
}

165
nomad/blocked_evals_test.go
View File

@ -53,6 +53,27 @@ func TestBlockedEvals_Block_SameJob(t *testing.T) {
}
}
func TestBlockedEvals_Block_PriorUnblocks(t *testing.T) {
blocked, _ := testBlockedEvals(t)
// Do unblocks prior to blocking
blocked.Unblock("v1:123", 1000)
blocked.Unblock("v1:123", 1001)
// Create two blocked evals and add them to the blocked tracker.
e := mock.Eval()
e.Status = structs.EvalStatusBlocked
e.ClassEligibility = map[string]bool{"v1:123": false, "v1:456": false}
e.SnapshotIndex = 999
blocked.Block(e)
// Verify block did track both
bStats := blocked.Stats()
if bStats.TotalBlocked != 1 || bStats.TotalEscaped != 0 {
t.Fatalf("bad: %#v", bStats)
}
}
func TestBlockedEvals_GetDuplicates(t *testing.T) {
blocked, _ := testBlockedEvals(t)
@ -105,7 +126,7 @@ func TestBlockedEvals_UnblockEscaped(t *testing.T) {
t.Fatalf("bad: %#v", bStats)
}
blocked.Unblock("v1:123")
blocked.Unblock("v1:123", 1000)
testutil.WaitForResult(func() (bool, error) {
// Verify Unblock caused an enqueue
@ -141,7 +162,7 @@ func TestBlockedEvals_UnblockEligible(t *testing.T) {
t.Fatalf("bad: %#v", blockedStats)
}
blocked.Unblock("v1:123")
blocked.Unblock("v1:123", 1000)
testutil.WaitForResult(func() (bool, error) {
// Verify Unblock caused an enqueue
@ -178,7 +199,7 @@ func TestBlockedEvals_UnblockIneligible(t *testing.T) {
}
// Should do nothing
blocked.Unblock("v1:123")
blocked.Unblock("v1:123", 1000)
testutil.WaitForResult(func() (bool, error) {
// Verify Unblock didn't cause an enqueue
@ -214,7 +235,7 @@ func TestBlockedEvals_UnblockUnknown(t *testing.T) {
}
// Should unblock because the eval hasn't seen this node class.
blocked.Unblock("v1:789")
blocked.Unblock("v1:789", 1000)
testutil.WaitForResult(func() (bool, error) {
// Verify Unblock causes an enqueue
@ -233,3 +254,139 @@ func TestBlockedEvals_UnblockUnknown(t *testing.T) {
t.Fatalf("err: %s", err)
})
}
// Test the block case in which the eval should be immediately unblocked since
// it is escaped and old
func TestBlockedEvals_Block_ImmediateUnblock_Escaped(t *testing.T) {
blocked, broker := testBlockedEvals(t)
// Do an unblock prior to blocking
blocked.Unblock("v1:123", 1000)
// Create a blocked eval that is eligible on a specific node class and add
// it to the blocked tracker.
e := mock.Eval()
e.Status = structs.EvalStatusBlocked
e.EscapedComputedClass = true
e.SnapshotIndex = 900
blocked.Block(e)
// Verify block caused the eval to be immediately unblocked
blockedStats := blocked.Stats()
if blockedStats.TotalBlocked != 0 && blockedStats.TotalEscaped != 0 {
t.Fatalf("bad: %#v", blockedStats)
}
testutil.WaitForResult(func() (bool, error) {
// Verify Unblock caused an enqueue
brokerStats := broker.Stats()
if brokerStats.TotalReady != 1 {
return false, fmt.Errorf("bad: %#v", brokerStats)
}
return true, nil
}, func(err error) {
t.Fatalf("err: %s", err)
})
}
// Test the block case in which the eval should be immediately unblocked since
// it there is an unblock on an unseen class
func TestBlockedEvals_Block_ImmediateUnblock_UnseenClass(t *testing.T) {
blocked, broker := testBlockedEvals(t)
// Do an unblock prior to blocking
blocked.Unblock("v1:123", 1000)
// Create a blocked eval that is eligible on a specific node class and add
// it to the blocked tracker.
e := mock.Eval()
e.Status = structs.EvalStatusBlocked
e.EscapedComputedClass = false
e.SnapshotIndex = 900
blocked.Block(e)
// Verify block caused the eval to be immediately unblocked
blockedStats := blocked.Stats()
if blockedStats.TotalBlocked != 0 && blockedStats.TotalEscaped != 0 {
t.Fatalf("bad: %#v", blockedStats)
}
testutil.WaitForResult(func() (bool, error) {
// Verify Unblock caused an enqueue
brokerStats := broker.Stats()
if brokerStats.TotalReady != 1 {
return false, fmt.Errorf("bad: %#v", brokerStats)
}
return true, nil
}, func(err error) {
t.Fatalf("err: %s", err)
})
}
// Test the block case in which the eval should be immediately unblocked since
// it a class it is eligible for has been unblocked
func TestBlockedEvals_Block_ImmediateUnblock_SeenClass(t *testing.T) {
blocked, broker := testBlockedEvals(t)
// Do an unblock prior to blocking
blocked.Unblock("v1:123", 1000)
// Create a blocked eval that is eligible on a specific node class and add
// it to the blocked tracker.
e := mock.Eval()
e.Status = structs.EvalStatusBlocked
e.ClassEligibility = map[string]bool{"v1:123": true, "v1:456": false}
e.SnapshotIndex = 900
blocked.Block(e)
// Verify block caused the eval to be immediately unblocked
blockedStats := blocked.Stats()
if blockedStats.TotalBlocked != 0 && blockedStats.TotalEscaped != 0 {
t.Fatalf("bad: %#v", blockedStats)
}
testutil.WaitForResult(func() (bool, error) {
// Verify Unblock caused an enqueue
brokerStats := broker.Stats()
if brokerStats.TotalReady != 1 {
return false, fmt.Errorf("bad: %#v", brokerStats)
}
return true, nil
}, func(err error) {
t.Fatalf("err: %s", err)
})
}
func TestBlockedEvals_UnblockFailed(t *testing.T) {
blocked, broker := testBlockedEvals(t)
// Create blocked evals that are due to failures
e := mock.Eval()
e.Status = structs.EvalStatusBlocked
e.TriggeredBy = structs.EvalTriggerMaxPlans
e.EscapedComputedClass = true
blocked.Block(e)
e2 := mock.Eval()
e2.Status = structs.EvalStatusBlocked
e2.TriggeredBy = structs.EvalTriggerMaxPlans
e2.ClassEligibility = map[string]bool{"v1:123": true, "v1:456": false}
blocked.Block(e2)
// Trigger an unblock fail
blocked.UnblockFailed()
testutil.WaitForResult(func() (bool, error) {
// Verify Unblock caused an enqueue
brokerStats := broker.Stats()
if brokerStats.TotalReady != 2 {
return false, fmt.Errorf("bad: %#v", brokerStats)
}
return true, nil
}, func(err error) {
t.Fatalf("err: %s", err)
})
}

40
nomad/eval_endpoint.go
View File

@ -202,6 +202,46 @@ func (e *Eval) Create(args *structs.EvalUpdateRequest,
return nil
}
// Reblock is used to reinsert an existing blocked evaluation into the blocked
// evaluation tracker.
func (e *Eval) Reblock(args *structs.EvalUpdateRequest, reply *structs.GenericResponse) error {
if done, err := e.srv.forward("Eval.Reblock", args, args, reply); done {
return err
}
defer metrics.MeasureSince([]string{"nomad", "eval", "reblock"}, time.Now())
// Ensure there is only a single update with token
if len(args.Evals) != 1 {
return fmt.Errorf("only a single eval can be reblocked")
}
eval := args.Evals[0]
// Verify the evaluation is outstanding, and that the tokens match.
if err := e.srv.evalBroker.OutstandingReset(eval.ID, args.EvalToken); err != nil {
return err
}
// Look for the eval
snap, err := e.srv.fsm.State().Snapshot()
if err != nil {
return err
}
out, err := snap.EvalByID(eval.ID)
if err != nil {
return err
}
if out == nil {
return fmt.Errorf("evaluation does not exist")
}
if out.Status != structs.EvalStatusBlocked {
return fmt.Errorf("evaluation not blocked")
}
// Reblock the eval
e.srv.blockedEvals.Block(eval)
return nil
}
// Reap is used to cleanup dead evaluations and allocations
func (e *Eval) Reap(args *structs.EvalDeleteRequest,
reply *structs.GenericResponse) error {

118
nomad/eval_endpoint_test.go
View File

@ -575,3 +575,121 @@ func TestEvalEndpoint_Allocations_Blocking(t *testing.T) {
t.Fatalf("bad: %#v", resp.Allocations)
}
}
func TestEvalEndpoint_Reblock_NonExistent(t *testing.T) {
s1 := testServer(t, nil)
defer s1.Shutdown()
codec := rpcClient(t, s1)
testutil.WaitForResult(func() (bool, error) {
return s1.evalBroker.Enabled(), nil
}, func(err error) {
t.Fatalf("should enable eval broker")
})
// Create the register request
eval1 := mock.Eval()
s1.evalBroker.Enqueue(eval1)
out, token, err := s1.evalBroker.Dequeue(defaultSched, time.Second)
if err != nil {
t.Fatalf("err: %v", err)
}
if out == nil {
t.Fatalf("missing eval")
}
get := &structs.EvalUpdateRequest{
Evals: []*structs.Evaluation{eval1},
EvalToken: token,
WriteRequest: structs.WriteRequest{Region: "global"},
}
var resp structs.GenericResponse
if err := msgpackrpc.CallWithCodec(codec, "Eval.Reblock", get, &resp); err == nil {
t.Fatalf("expect error since eval does not exist")
}
}
func TestEvalEndpoint_Reblock_NonBlocked(t *testing.T) {
s1 := testServer(t, nil)
defer s1.Shutdown()
codec := rpcClient(t, s1)
testutil.WaitForResult(func() (bool, error) {
return s1.evalBroker.Enabled(), nil
}, func(err error) {
t.Fatalf("should enable eval broker")
})
// Create the eval
eval1 := mock.Eval()
s1.evalBroker.Enqueue(eval1)
// Insert it into the state store
if err := s1.fsm.State().UpsertEvals(1000, []*structs.Evaluation{eval1}); err != nil {
t.Fatal(err)
}
out, token, err := s1.evalBroker.Dequeue(defaultSched, time.Second)
if err != nil {
t.Fatalf("err: %v", err)
}
if out == nil {
t.Fatalf("missing eval")
}
get := &structs.EvalUpdateRequest{
Evals: []*structs.Evaluation{eval1},
EvalToken: token,
WriteRequest: structs.WriteRequest{Region: "global"},
}
var resp structs.GenericResponse
if err := msgpackrpc.CallWithCodec(codec, "Eval.Reblock", get, &resp); err == nil {
t.Fatalf("should error since eval was not in blocked state", err)
}
}
func TestEvalEndpoint_Reblock(t *testing.T) {
s1 := testServer(t, nil)
defer s1.Shutdown()
codec := rpcClient(t, s1)
testutil.WaitForResult(func() (bool, error) {
return s1.evalBroker.Enabled(), nil
}, func(err error) {
t.Fatalf("should enable eval broker")
})
// Create the eval
eval1 := mock.Eval()
eval1.Status = structs.EvalStatusBlocked
s1.evalBroker.Enqueue(eval1)
// Insert it into the state store
if err := s1.fsm.State().UpsertEvals(1000, []*structs.Evaluation{eval1}); err != nil {
t.Fatal(err)
}
out, token, err := s1.evalBroker.Dequeue(defaultSched, time.Second)
if err != nil {
t.Fatalf("err: %v", err)
}
if out == nil {
t.Fatalf("missing eval")
}
get := &structs.EvalUpdateRequest{
Evals: []*structs.Evaluation{eval1},
EvalToken: token,
WriteRequest: structs.WriteRequest{Region: "global"},
}
var resp structs.GenericResponse
if err := msgpackrpc.CallWithCodec(codec, "Eval.Reblock", get, &resp); err != nil {
t.Fatalf("err: %v", err)
}
// Check that it is blocked
bStats := s1.blockedEvals.Stats()
if bStats.TotalBlocked+bStats.TotalEscaped == 0 {
t.Fatalf("ReblockEval didn't insert eval into the blocked eval tracker")
}
}

6
nomad/fsm.go
View File

@ -158,7 +158,7 @@ func (n *nomadFSM) applyUpsertNode(buf []byte, index uint64) interface{} {
// Unblock evals for the nodes computed node class if it is in a ready
// state.
if req.Node.Status == structs.NodeStatusReady {
n.blockedEvals.Unblock(req.Node.ComputedClass)
n.blockedEvals.Unblock(req.Node.ComputedClass, index)
}
return nil
@ -199,7 +199,7 @@ func (n *nomadFSM) applyStatusUpdate(buf []byte, index uint64) interface{} {
return err
}
n.blockedEvals.Unblock(node.ComputedClass)
n.blockedEvals.Unblock(node.ComputedClass, index)
}
return nil
@ -420,7 +420,7 @@ func (n *nomadFSM) applyAllocClientUpdate(buf []byte, index uint64) interface{}
return err
}
n.blockedEvals.Unblock(node.ComputedClass)
n.blockedEvals.Unblock(node.ComputedClass, index)
}
}

25
nomad/leader.go
View File

@ -11,6 +11,13 @@ import (
"github.com/hashicorp/serf/serf"
)
const (
// failedEvalUnblockInterval is the interval at which failed evaluations are
// unblocked to re-enter the scheduler. A failed evaluation occurs under
// high contention when the schedulers plan does not make progress.
failedEvalUnblockInterval = 1 * time.Minute
)
// monitorLeadership is used to monitor if we acquire or lose our role
// as the leader in the Raft cluster. There is some work the leader is
// expected to do, so we must react to changes
@ -143,6 +150,9 @@ func (s *Server) establishLeadership(stopCh chan struct{}) error {
// Reap any duplicate blocked evaluations
go s.reapDupBlockedEvaluations(stopCh)
// Periodically unblock failed allocations
go s.periodicUnblockFailedEvals(stopCh)
// Setup the heartbeat timers. This is done both when starting up or when
// a leader fail over happens. Since the timers are maintained by the leader
// node, effectively this means all the timers are renewed at the time of failover.
@ -341,6 +351,21 @@ func (s *Server) reapDupBlockedEvaluations(stopCh chan struct{}) {
}
}
// periodicUnblockFailedEvals periodically unblocks failed, blocked evaluations.
func (s *Server) periodicUnblockFailedEvals(stopCh chan struct{}) {
ticker := time.NewTimer(failedEvalUnblockInterval)
defer ticker.Stop()
for {
select {
case <-stopCh:
return
case <-ticker.C:
// Unblock the failed allocations
s.blockedEvals.UnblockFailed()
}
}
}
// revokeLeadership is invoked once we step down as leader.
// This is used to cleanup any state that may be specific to a leader.
func (s *Server) revokeLeadership() error {

26
nomad/state/state_store.go
View File

@ -972,6 +972,32 @@ func (s *StateStore) Allocs() (memdb.ResultIterator, error) {
return iter, nil
}
// LastIndex returns the greatest index value for all indexes
func (s *StateStore) LatestIndex() (uint64, error) {
indexes, err := s.Indexes()
if err != nil {
return 0, err
}
var max uint64 = 0
for {
raw := indexes.Next()
if raw == nil {
break
}
// Prepare the request struct
idx := raw.(*IndexEntry)
// Determine the max
if idx.Value > max {
max = idx.Value
}
}
return max, nil
}
// Index finds the matching index value
func (s *StateStore) Index(name string) (uint64, error) {
txn := s.db.Txn(false)

22
nomad/state/state_store_test.go
View File

@ -1019,6 +1019,28 @@ func TestStateStore_Indexes(t *testing.T) {
}
}
func TestStateStore_LatestIndex(t *testing.T) {
state := testStateStore(t)
if err := state.UpsertNode(1000, mock.Node()); err != nil {
t.Fatalf("err: %v", err)
}
exp := uint64(2000)
if err := state.UpsertJob(exp, mock.Job()); err != nil {
t.Fatalf("err: %v", err)
}
latest, err := state.LatestIndex()
if err != nil {
t.Fatalf("err: %v", err)
}
if latest != exp {
t.Fatalf("LatestIndex() returned %d; want %d", latest, exp)
}
}
func TestStateStore_RestoreIndex(t *testing.T) {
state := testStateStore(t)

6
nomad/structs/structs.go
View File

@ -2570,6 +2570,7 @@ const (
EvalTriggerNodeUpdate = "node-update"
EvalTriggerScheduled = "scheduled"
EvalTriggerRollingUpdate = "rolling-update"
EvalTriggerMaxPlans = "max-plan-attempts"
)
const (
@ -2671,6 +2672,11 @@ type Evaluation struct {
// during the evaluation. This should not be set during normal operations.
AnnotatePlan bool
// SnapshotIndex is the Raft index of the snapshot used to process the
// evaluation. As such it will only be set once it has gone through the
// scheduler.
SnapshotIndex uint64
// Raft Indexes
CreateIndex uint64
ModifyIndex uint64

55
nomad/worker.go
View File

@ -59,6 +59,11 @@ type Worker struct {
failures uint
evalToken string
// snapshotIndex is the index of the snapshot in which the scheduler was
// first envoked. It is used to mark the SnapshotIndex of evaluations
// Created, Updated or Reblocked.
snapshotIndex uint64
}
// NewWorker starts a new worker associated with the given server
@ -241,6 +246,12 @@ func (w *Worker) invokeScheduler(eval *structs.Evaluation, token string) error {
return fmt.Errorf("failed to snapshot state: %v", err)
}
// Store the snapshot's index
w.snapshotIndex, err = snap.LatestIndex()
if err != nil {
return fmt.Errorf("failed to determine snapshot's index: %v", err)
}
// Create the scheduler, or use the special system scheduler
var sched scheduler.Scheduler
if eval.Type == structs.JobTypeCore {
@ -334,6 +345,9 @@ func (w *Worker) UpdateEval(eval *structs.Evaluation) error {
}
defer metrics.MeasureSince([]string{"nomad", "worker", "update_eval"}, time.Now())
// Store the snapshot index in the eval
eval.SnapshotIndex = w.snapshotIndex
// Setup the request
req := structs.EvalUpdateRequest{
Evals: []*structs.Evaluation{eval},
@ -369,6 +383,9 @@ func (w *Worker) CreateEval(eval *structs.Evaluation) error {
}
defer metrics.MeasureSince([]string{"nomad", "worker", "create_eval"}, time.Now())
// Store the snapshot index in the eval
eval.SnapshotIndex = w.snapshotIndex
// Setup the request
req := structs.EvalUpdateRequest{
Evals: []*structs.Evaluation{eval},
@ -395,6 +412,44 @@ SUBMIT:
return nil
}
// ReblockEval is used to reinsert a blocked evaluation into the blocked eval
// tracker. This allows the worker to act as the planner for the scheduler.
func (w *Worker) ReblockEval(eval *structs.Evaluation) error {
// Check for a shutdown before plan submission
if w.srv.IsShutdown() {
return fmt.Errorf("shutdown while planning")
}
defer metrics.MeasureSince([]string{"nomad", "worker", "reblock_eval"}, time.Now())
// Store the snapshot index in the eval
eval.SnapshotIndex = w.snapshotIndex
// Setup the request
req := structs.EvalUpdateRequest{
Evals: []*structs.Evaluation{eval},
EvalToken: w.evalToken,
WriteRequest: structs.WriteRequest{
Region: w.srv.config.Region,
},
}
var resp structs.GenericResponse
SUBMIT:
// Make the RPC call
if err := w.srv.RPC("Eval.Reblock", &req, &resp); err != nil {
w.logger.Printf("[ERR] worker: failed to reblock evaluation %#v: %v",
eval, err)
if w.shouldResubmit(err) && !w.backoffErr(backoffBaselineSlow, backoffLimitSlow) {
goto SUBMIT
}
return err
} else {
w.logger.Printf("[DEBUG] worker: reblocked evaluation %#v", eval)
w.backoffReset()
}
return nil
}
// shouldResubmit checks if a given error should be swallowed and the plan
// resubmitted after a backoff. Usually these are transient errors that
// the cluster should heal from quickly.

73
nomad/worker_test.go
View File

@ -398,6 +398,9 @@ func TestWorker_UpdateEval(t *testing.T) {
if out.Status != structs.EvalStatusComplete {
t.Fatalf("bad: %v", out)
}
if out.SnapshotIndex != w.snapshotIndex {
t.Fatalf("bad: %v", out)
}
}
func TestWorker_CreateEval(t *testing.T) {
@ -441,4 +444,74 @@ func TestWorker_CreateEval(t *testing.T) {
if out.PreviousEval != eval1.ID {
t.Fatalf("bad: %v", out)
}
if out.SnapshotIndex != w.snapshotIndex {
t.Fatalf("bad: %v", out)
}
}
func TestWorker_ReblockEval(t *testing.T) {
s1 := testServer(t, func(c *Config) {
c.NumSchedulers = 0
c.EnabledSchedulers = []string{structs.JobTypeService}
})
defer s1.Shutdown()
testutil.WaitForLeader(t, s1.RPC)
// Create the blocked eval
eval1 := mock.Eval()
eval1.Status = structs.EvalStatusBlocked
// Insert it into the state store
if err := s1.fsm.State().UpsertEvals(1000, []*structs.Evaluation{eval1}); err != nil {
t.Fatal(err)
}
// Enqueue the eval and then dequeue
s1.evalBroker.Enqueue(eval1)
evalOut, token, err := s1.evalBroker.Dequeue([]string{eval1.Type}, time.Second)
if err != nil {
t.Fatalf("err: %v", err)
}
if evalOut != eval1 {
t.Fatalf("Bad eval")
}
eval2 := evalOut.Copy()
// Attempt to reblock eval
w := &Worker{srv: s1, logger: s1.logger, evalToken: token}
err = w.ReblockEval(eval2)
if err != nil {
t.Fatalf("err: %v", err)
}
// Ack the eval
w.sendAck(evalOut.ID, token, true)
// Check that it is blocked
bStats := s1.blockedEvals.Stats()
if bStats.TotalBlocked+bStats.TotalEscaped != 1 {
t.Fatalf("ReblockEval didn't insert eval into the blocked eval tracker: %#v", bStats)
}
// Check that the snapshot index was set properly by unblocking the eval and
// then dequeuing.
s1.blockedEvals.Unblock("foobar", 1000)
reblockedEval, _, err := s1.evalBroker.Dequeue([]string{eval1.Type}, 1*time.Second)
if err != nil {
t.Fatalf("err: %v", err)
}
if reblockedEval == nil {
t.Fatalf("Nil eval")
}
if reblockedEval.ID != eval1.ID {
t.Fatalf("Bad eval")
}
// Check that the SnapshotIndex is set
if reblockedEval.SnapshotIndex != w.snapshotIndex {
t.Fatalf("incorrect snapshot index; got %d; want %d",
reblockedEval.SnapshotIndex, w.snapshotIndex)
}
}

24
scheduler/generic_sched.go
View File

@ -114,7 +114,7 @@ func (s *GenericScheduler) Process(eval *structs.Evaluation) error {
// Scheduling was tried but made no forward progress so create a
// blocked eval to retry once resources become available.
var mErr multierror.Error
if err := s.createBlockedEval(); err != nil {
if err := s.createBlockedEval(true); err != nil {
mErr.Errors = append(mErr.Errors, err)
}
if err := setStatus(s.logger, s.planner, s.eval, s.nextEval, s.blocked, statusErr.EvalStatus, err.Error()); err != nil {
@ -125,12 +125,19 @@ func (s *GenericScheduler) Process(eval *structs.Evaluation) error {
return err
}
// If the current evaluation is a blocked evaluation and we didn't place
// everything, do not update the status to complete.
if s.eval.Status == structs.EvalStatusBlocked && len(s.eval.FailedTGAllocs) != 0 {
return s.planner.ReblockEval(s.eval)
}
// Update the status to complete
return setStatus(s.logger, s.planner, s.eval, s.nextEval, s.blocked, structs.EvalStatusComplete, "")
}
// createBlockedEval creates a blocked eval and stores it.
func (s *GenericScheduler) createBlockedEval() error {
// createBlockedEval creates a blocked eval and submits it to the planner. If
// failure is set to true, the eval's trigger reason reflects that.
func (s *GenericScheduler) createBlockedEval(planFailure bool) error {
e := s.ctx.Eligibility()
escaped := e.HasEscaped()
@ -141,6 +148,10 @@ func (s *GenericScheduler) createBlockedEval() error {
}
s.blocked = s.eval.CreateBlockedEval(classEligibility, escaped)
if planFailure {
s.blocked.TriggeredBy = structs.EvalTriggerMaxPlans
}
return s.planner.CreateEval(s.blocked)
}
@ -177,9 +188,10 @@ func (s *GenericScheduler) process() (bool, error) {
}
// If there are failed allocations, we need to create a blocked evaluation
// to place the failed allocations when resources become available.
if len(s.eval.FailedTGAllocs) != 0 && s.blocked == nil {
if err := s.createBlockedEval(); err != nil {
// to place the failed allocations when resources become available. If the
// current evaluation is already a blocked eval, we reuse it.
if s.eval.Status != structs.EvalStatusBlocked && len(s.eval.FailedTGAllocs) != 0 && s.blocked == nil {
if err := s.createBlockedEval(false); err != nil {
s.logger.Printf("[ERR] sched: %#v failed to make blocked eval: %v", s.eval, err)
return false, err
}

122
scheduler/generic_sched_test.go
View File

@ -275,7 +275,7 @@ func TestServiceSched_JobRegister_AllocFail(t *testing.T) {
h.AssertEvalStatus(t, structs.EvalStatusComplete)
}
func TestServiceSched_JobRegister_BlockedEval(t *testing.T) {
func TestServiceSched_JobRegister_CreateBlockedEval(t *testing.T) {
h := NewHarness(t)
// Create a full node
@ -454,6 +454,126 @@ func TestServiceSched_JobRegister_FeasibleAndInfeasibleTG(t *testing.T) {
h.AssertEvalStatus(t, structs.EvalStatusComplete)
}
func TestServiceSched_EvaluateBlockedEval(t *testing.T) {
h := NewHarness(t)
// Create a job and set the task group count to zero.
job := mock.Job()
noErr(t, h.State.UpsertJob(h.NextIndex(), job))
// Create a mock blocked evaluation
eval := &structs.Evaluation{
ID: structs.GenerateUUID(),
Status: structs.EvalStatusBlocked,
Priority: job.Priority,
TriggeredBy: structs.EvalTriggerJobRegister,
JobID: job.ID,
}
// Insert it into the state store
noErr(t, h.State.UpsertEvals(h.NextIndex(), []*structs.Evaluation{eval}))
// Process the evaluation
err := h.Process(NewServiceScheduler, eval)
if err != nil {
t.Fatalf("err: %v", err)
}
// Ensure there was no plan
if len(h.Plans) != 0 {
t.Fatalf("bad: %#v", h.Plans)
}
// Ensure that the eval was reblocked
if len(h.ReblockEvals) != 1 {
t.Fatalf("bad: %#v", h.ReblockEvals)
}
if h.ReblockEvals[0].ID != eval.ID {
t.Fatalf("expect same eval to be reblocked; got %q; want %q", h.ReblockEvals[0].ID, eval.ID)
}
// Ensure the eval status was not updated
if len(h.Evals) != 0 {
t.Fatalf("Existing eval should not have status set")
}
}
func TestServiceSched_EvaluateBlockedEval_Finished(t *testing.T) {
h := NewHarness(t)
// Create some nodes
for i := 0; i < 10; i++ {
node := mock.Node()
noErr(t, h.State.UpsertNode(h.NextIndex(), node))
}
// Create a job and set the task group count to zero.
job := mock.Job()
noErr(t, h.State.UpsertJob(h.NextIndex(), job))
// Create a mock blocked evaluation
eval := &structs.Evaluation{
ID: structs.GenerateUUID(),
Status: structs.EvalStatusBlocked,
Priority: job.Priority,
TriggeredBy: structs.EvalTriggerJobRegister,
JobID: job.ID,
}
// Insert it into the state store
noErr(t, h.State.UpsertEvals(h.NextIndex(), []*structs.Evaluation{eval}))
// Process the evaluation
err := h.Process(NewServiceScheduler, eval)
if err != nil {
t.Fatalf("err: %v", err)
}
// Ensure a single plan
if len(h.Plans) != 1 {
t.Fatalf("bad: %#v", h.Plans)
}
plan := h.Plans[0]
// Ensure the plan doesn't have annotations.
if plan.Annotations != nil {
t.Fatalf("expected no annotations")
}
// Ensure the eval has no spawned blocked eval
if len(h.Evals) != 1 {
t.Fatalf("bad: %#v", h.Evals)
if h.Evals[0].BlockedEval != "" {
t.Fatalf("bad: %#v", h.Evals[0])
}
}
// Ensure the plan allocated
var planned []*structs.Allocation
for _, allocList := range plan.NodeAllocation {
planned = append(planned, allocList...)
}
if len(planned) != 10 {
t.Fatalf("bad: %#v", plan)
}
// Lookup the allocations by JobID
out, err := h.State.AllocsByJob(job.ID)
noErr(t, err)
// Ensure all allocations placed
if len(out) != 10 {
t.Fatalf("bad: %#v", out)
}
// Ensure the eval was not reblocked
if len(h.ReblockEvals) != 0 {
t.Fatalf("Existing eval should not have been reblocked as it placed all allocations")
}
h.AssertEvalStatus(t, structs.EvalStatusComplete)
}
func TestServiceSched_JobModify(t *testing.T) {
h := NewHarness(t)

6
scheduler/scheduler.go
View File

@ -87,4 +87,10 @@ type Planner interface {
// CreateEval is used to create an evaluation. This should set the
// PreviousEval to that of the current evaluation.
CreateEval(*structs.Evaluation) error
// ReblockEval takes a blocked evaluation and re-inserts it into the blocked
// evaluation tracker. This update occurs only in-memory on the leader. The
// evaluation must exist in a blocked state prior to this being called such
// that on leader changes, the evaluation will be reblocked properly.
ReblockEval(*structs.Evaluation) error
}

28
scheduler/testing.go
View File

@ -1,6 +1,7 @@
package scheduler
import (
"fmt"
"log"
"os"
"sync"
@ -29,6 +30,10 @@ func (r *RejectPlan) CreateEval(*structs.Evaluation) error {
return nil
}
func (r *RejectPlan) ReblockEval(*structs.Evaluation) error {
return nil
}
// Harness is a lightweight testing harness for schedulers. It manages a state
// store copy and provides the planner interface. It can be extended for various
// testing uses or for invoking the scheduler without side effects.
@ -41,6 +46,7 @@ type Harness struct {
Plans []*structs.Plan
Evals []*structs.Evaluation
CreateEvals []*structs.Evaluation
ReblockEvals []*structs.Evaluation
nextIndex uint64
nextIndexLock sync.Mutex
@ -138,6 +144,28 @@ func (h *Harness) CreateEval(eval *structs.Evaluation) error {
return nil
}
func (h *Harness) ReblockEval(eval *structs.Evaluation) error {
// Ensure sequential plan application
h.planLock.Lock()
defer h.planLock.Unlock()
// Check that the evaluation was already blocked.
old, err := h.State.EvalByID(eval.ID)
if err != nil {
return err
}
if old == nil {
return fmt.Errorf("evaluation does not exist to be reblocked")
}
if old.Status != structs.EvalStatusBlocked {
return fmt.Errorf("evaluation %q is not already in a blocked state", old.ID)
}
h.ReblockEvals = append(h.ReblockEvals, eval)
return nil
}
// NextIndex returns the next index
func (h *Harness) NextIndex() uint64 {
h.nextIndexLock.Lock()