lib/dispatchcloud/scheduler/run_queue.go

   1 // Copyright (C) The Arvados Authors. All rights reserved.
   2 //
   3 // SPDX-License-Identifier: AGPL-3.0
   4
   5 package scheduler
   6
   7 import (
   8         "sort"
   9         "time"
  10
  11         "git.arvados.org/arvados.git/lib/dispatchcloud/container"
  12         "git.arvados.org/arvados.git/sdk/go/arvados"
  13         "github.com/sirupsen/logrus"
  14 )
  15
  16 func (sch *Scheduler) runQueue() {
  17         unsorted, _ := sch.queue.Entries()
  18         sorted := make([]container.QueueEnt, 0, len(unsorted))
  19         for _, ent := range unsorted {
  20                 sorted = append(sorted, ent)
  21         }
  22         sort.Slice(sorted, func(i, j int) bool {
  23                 return sorted[i].Container.Priority > sorted[j].Container.Priority
  24         })
  25
  26         running := sch.pool.Running()
  27         unalloc := sch.pool.Unallocated()
  28
  29         sch.logger.WithFields(logrus.Fields{
  30                 "Containers": len(sorted),
  31                 "Processes":  len(running),
  32         }).Debug("runQueue")
  33
  34         dontstart := map[arvados.InstanceType]bool{}
  35         var overquota []container.QueueEnt // entries that are unmappable because of worker pool quota
  36         var containerAllocatedWorkerBootingCount int
  37
  38 tryrun:
  39         for i, ctr := range sorted {
  40                 ctr, it := ctr.Container, ctr.InstanceType
  41                 logger := sch.logger.WithFields(logrus.Fields{
  42                         "ContainerUUID": ctr.UUID,
  43                         "InstanceType":  it.Name,
  44                 })
  45                 if _, running := running[ctr.UUID]; running || ctr.Priority < 1 {
  46                         continue
  47                 }
  48                 switch ctr.State {
  49                 case arvados.ContainerStateQueued:
  50                         if unalloc[it] < 1 && sch.pool.AtQuota() {
  51                                 logger.Debug("not locking: AtQuota and no unalloc workers")
  52                                 overquota = sorted[i:]
  53                                 break tryrun
  54                         }
  55                         if sch.pool.KillContainer(ctr.UUID, "about to lock") {
  56                                 logger.Info("not locking: crunch-run process from previous attempt has not exited")
  57                                 continue
  58                         }
  59                         go sch.lockContainer(logger, ctr.UUID)
  60                         unalloc[it]--
  61                 case arvados.ContainerStateLocked:
  62                         if unalloc[it] > 0 {
  63                                 unalloc[it]--
  64                         } else if sch.pool.AtQuota() {
  65                                 // Don't let lower-priority containers
  66                                 // starve this one by using keeping
  67                                 // idle workers alive on different
  68                                 // instance types.
  69                                 logger.Debug("overquota")
  70                                 overquota = sorted[i:]
  71                                 break tryrun
  72                         } else if logger.Info("creating new instance"); sch.pool.Create(it) {
  73                                 // Success. (Note pool.Create works
  74                                 // asynchronously and does its own
  75                                 // logging, so we don't need to.)
  76                         } else {
  77                                 // Failed despite not being at quota,
  78                                 // e.g., cloud ops throttled.  TODO:
  79                                 // avoid getting starved here if
  80                                 // instances of a specific type always
  81                                 // fail.
  82                                 continue
  83                         }
  84
  85                         if dontstart[it] {
  86                                 // We already tried & failed to start
  87                                 // a higher-priority container on the
  88                                 // same instance type. Don't let this
  89                                 // one sneak in ahead of it.
  90                         } else if sch.pool.KillContainer(ctr.UUID, "about to start") {
  91                                 logger.Info("not restarting yet: crunch-run process from previous attempt has not exited")
  92                         } else if sch.pool.StartContainer(it, ctr) {
  93                                 // Success.
  94                         } else {
  95                                 containerAllocatedWorkerBootingCount += 1
  96                                 dontstart[it] = true
  97                         }
  98                 }
  99         }
 100
 101         sch.mContainersAllocatedNotStarted.Set(float64(containerAllocatedWorkerBootingCount))
 102         sch.mContainersNotAllocatedOverQuota.Set(float64(len(overquota)))
 103
 104         if len(overquota) > 0 {
 105                 // Unlock any containers that are unmappable while
 106                 // we're at quota.
 107                 for _, ctr := range overquota {
 108                         ctr := ctr.Container
 109                         if ctr.State == arvados.ContainerStateLocked {
 110                                 logger := sch.logger.WithField("ContainerUUID", ctr.UUID)
 111                                 logger.Debug("unlock because pool capacity is used by higher priority containers")
 112                                 err := sch.queue.Unlock(ctr.UUID)
 113                                 if err != nil {
 114                                         logger.WithError(err).Warn("error unlocking")
 115                                 }
 116                         }
 117                 }
 118                 // Shut down idle workers that didn't get any
 119                 // containers mapped onto them before we hit quota.
 120                 for it, n := range unalloc {
 121                         if n < 1 {
 122                                 continue
 123                         }
 124                         sch.pool.Shutdown(it)
 125                 }
 126         }
 127 }
 128
 129 // Lock the given container. Should be called in a new goroutine.
 130 func (sch *Scheduler) lockContainer(logger logrus.FieldLogger, uuid string) {
 131         if !sch.uuidLock(uuid, "lock") {
 132                 return
 133         }
 134         defer sch.uuidUnlock(uuid)
 135         if ctr, ok := sch.queue.Get(uuid); !ok || ctr.State != arvados.ContainerStateQueued {
 136                 // This happens if the container has been cancelled or
 137                 // locked since runQueue called sch.queue.Entries(),
 138                 // possibly by a lockContainer() call from a previous
 139                 // runQueue iteration. In any case, we will respond
 140                 // appropriately on the next runQueue iteration, which
 141                 // will have already been triggered by the queue
 142                 // update.
 143                 logger.WithField("State", ctr.State).Debug("container no longer queued by the time we decided to lock it, doing nothing")
 144                 return
 145         }
 146         err := sch.queue.Lock(uuid)
 147         if err != nil {
 148                 logger.WithError(err).Warn("error locking container")
 149                 return
 150         }
 151         logger.Debug("lock succeeded")
 152         ctr, ok := sch.queue.Get(uuid)
 153         if !ok {
 154                 logger.Error("(BUG?) container disappeared from queue after Lock succeeded")
 155         } else if ctr.State != arvados.ContainerStateLocked {
 156                 logger.Warnf("(race?) container has state=%q after Lock succeeded", ctr.State)
 157         }
 158 }
 159
 160 // Acquire a non-blocking lock for specified UUID, returning true if
 161 // successful.  The op argument is used only for debug logs.
 162 //
 163 // If the lock is not available, uuidLock arranges to wake up the
 164 // scheduler after a short delay, so it can retry whatever operation
 165 // is trying to get the lock (if that operation is still worth doing).
 166 //
 167 // This mechanism helps avoid spamming the controller/database with
 168 // concurrent updates for any single container, even when the
 169 // scheduler loop is running frequently.
 170 func (sch *Scheduler) uuidLock(uuid, op string) bool {
 171         sch.mtx.Lock()
 172         defer sch.mtx.Unlock()
 173         logger := sch.logger.WithFields(logrus.Fields{
 174                 "ContainerUUID": uuid,
 175                 "Op":            op,
 176         })
 177         if op, locked := sch.uuidOp[uuid]; locked {
 178                 logger.Debugf("uuidLock not available, Op=%s in progress", op)
 179                 // Make sure the scheduler loop wakes up to retry.
 180                 sch.wakeup.Reset(time.Second / 4)
 181                 return false
 182         }
 183         logger.Debug("uuidLock acquired")
 184         sch.uuidOp[uuid] = op
 185         return true
 186 }
 187
 188 func (sch *Scheduler) uuidUnlock(uuid string) {
 189         sch.mtx.Lock()
 190         defer sch.mtx.Unlock()
 191         delete(sch.uuidOp, uuid)
 192 }