424 lines
12 KiB
Go
424 lines
12 KiB
Go
package nomad
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import (
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"fmt"
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"math"
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"time"
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memdb "github.com/hashicorp/go-memdb"
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"github.com/hashicorp/nomad/nomad/state"
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"github.com/hashicorp/nomad/nomad/structs"
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"github.com/hashicorp/nomad/scheduler"
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)
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var (
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// maxIdsPerReap is the maximum number of evals and allocations to reap in a
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// single Raft transaction. This is to ensure that the Raft message does not
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// become too large.
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maxIdsPerReap = (1024 * 256) / 36 // 0.25 MB of ids.
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)
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// CoreScheduler is a special "scheduler" that is registered
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// as "_core". It is used to run various administrative work
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// across the cluster.
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type CoreScheduler struct {
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srv *Server
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snap *state.StateSnapshot
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}
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// NewCoreScheduler is used to return a new system scheduler instance
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func NewCoreScheduler(srv *Server, snap *state.StateSnapshot) scheduler.Scheduler {
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s := &CoreScheduler{
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srv: srv,
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snap: snap,
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}
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return s
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}
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// Process is used to implement the scheduler.Scheduler interface
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func (c *CoreScheduler) Process(eval *structs.Evaluation) error {
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switch eval.JobID {
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case structs.CoreJobEvalGC:
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return c.evalGC(eval)
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case structs.CoreJobNodeGC:
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return c.nodeGC(eval)
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case structs.CoreJobJobGC:
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return c.jobGC(eval)
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case structs.CoreJobForceGC:
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return c.forceGC(eval)
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default:
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return fmt.Errorf("core scheduler cannot handle job '%s'", eval.JobID)
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}
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}
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// forceGC is used to garbage collect all eligible objects.
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func (c *CoreScheduler) forceGC(eval *structs.Evaluation) error {
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if err := c.jobGC(eval); err != nil {
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return err
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}
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if err := c.evalGC(eval); err != nil {
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return err
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}
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// Node GC must occur after the others to ensure the allocations are
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// cleared.
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return c.nodeGC(eval)
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}
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// jobGC is used to garbage collect eligible jobs.
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func (c *CoreScheduler) jobGC(eval *structs.Evaluation) error {
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// Get all the jobs eligible for garbage collection.
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ws := memdb.NewWatchSet()
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iter, err := c.snap.JobsByGC(ws, true)
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if err != nil {
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return err
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}
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var oldThreshold uint64
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if eval.JobID == structs.CoreJobForceGC {
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// The GC was forced, so set the threshold to its maximum so everything
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// will GC.
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oldThreshold = math.MaxUint64
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c.srv.logger.Println("[DEBUG] sched.core: forced job GC")
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} else {
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// Get the time table to calculate GC cutoffs.
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tt := c.srv.fsm.TimeTable()
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cutoff := time.Now().UTC().Add(-1 * c.srv.config.JobGCThreshold)
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oldThreshold = tt.NearestIndex(cutoff)
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c.srv.logger.Printf("[DEBUG] sched.core: job GC: scanning before index %d (%v)",
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oldThreshold, c.srv.config.JobGCThreshold)
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}
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// Collect the allocations, evaluations and jobs to GC
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var gcAlloc, gcEval, gcJob []string
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OUTER:
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for i := iter.Next(); i != nil; i = iter.Next() {
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job := i.(*structs.Job)
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// Ignore new jobs.
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if job.CreateIndex > oldThreshold {
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continue
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}
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ws := memdb.NewWatchSet()
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evals, err := c.snap.EvalsByJob(ws, job.ID)
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if err != nil {
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c.srv.logger.Printf("[ERR] sched.core: failed to get evals for job %s: %v", job.ID, err)
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continue
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}
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allEvalsGC := true
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var jobAlloc, jobEval []string
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for _, eval := range evals {
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gc, allocs, err := c.gcEval(eval, oldThreshold, true)
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if err != nil {
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continue OUTER
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}
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if gc {
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jobEval = append(jobEval, eval.ID)
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jobAlloc = append(jobAlloc, allocs...)
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} else {
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allEvalsGC = false
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break
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}
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}
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// Job is eligible for garbage collection
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if allEvalsGC {
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gcJob = append(gcJob, job.ID)
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gcAlloc = append(gcAlloc, jobAlloc...)
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gcEval = append(gcEval, jobEval...)
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}
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}
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// Fast-path the nothing case
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if len(gcEval) == 0 && len(gcAlloc) == 0 && len(gcJob) == 0 {
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return nil
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}
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c.srv.logger.Printf("[DEBUG] sched.core: job GC: %d jobs, %d evaluations, %d allocs eligible",
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len(gcJob), len(gcEval), len(gcAlloc))
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// Reap the evals and allocs
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if err := c.evalReap(gcEval, gcAlloc); err != nil {
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return err
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}
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// Call to the leader to deregister the jobs.
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for _, job := range gcJob {
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req := structs.JobDeregisterRequest{
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JobID: job,
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WriteRequest: structs.WriteRequest{
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Region: c.srv.config.Region,
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},
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}
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var resp structs.JobDeregisterResponse
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if err := c.srv.RPC("Job.Deregister", &req, &resp); err != nil {
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c.srv.logger.Printf("[ERR] sched.core: job deregister failed: %v", err)
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return err
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}
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}
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return nil
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}
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// evalGC is used to garbage collect old evaluations
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func (c *CoreScheduler) evalGC(eval *structs.Evaluation) error {
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// Iterate over the evaluations
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ws := memdb.NewWatchSet()
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iter, err := c.snap.Evals(ws)
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if err != nil {
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return err
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}
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var oldThreshold uint64
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if eval.JobID == structs.CoreJobForceGC {
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// The GC was forced, so set the threshold to its maximum so everything
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// will GC.
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oldThreshold = math.MaxUint64
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c.srv.logger.Println("[DEBUG] sched.core: forced eval GC")
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} else {
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// Compute the old threshold limit for GC using the FSM
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// time table. This is a rough mapping of a time to the
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// Raft index it belongs to.
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tt := c.srv.fsm.TimeTable()
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cutoff := time.Now().UTC().Add(-1 * c.srv.config.EvalGCThreshold)
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oldThreshold = tt.NearestIndex(cutoff)
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c.srv.logger.Printf("[DEBUG] sched.core: eval GC: scanning before index %d (%v)",
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oldThreshold, c.srv.config.EvalGCThreshold)
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}
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// Collect the allocations and evaluations to GC
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var gcAlloc, gcEval []string
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for raw := iter.Next(); raw != nil; raw = iter.Next() {
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eval := raw.(*structs.Evaluation)
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// The Evaluation GC should not handle batch jobs since those need to be
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// garbage collected in one shot
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gc, allocs, err := c.gcEval(eval, oldThreshold, false)
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if err != nil {
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return err
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}
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if gc {
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gcEval = append(gcEval, eval.ID)
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}
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gcAlloc = append(gcAlloc, allocs...)
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}
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// Fast-path the nothing case
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if len(gcEval) == 0 && len(gcAlloc) == 0 {
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return nil
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}
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c.srv.logger.Printf("[DEBUG] sched.core: eval GC: %d evaluations, %d allocs eligible",
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len(gcEval), len(gcAlloc))
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return c.evalReap(gcEval, gcAlloc)
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}
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// gcEval returns whether the eval should be garbage collected given a raft
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// threshold index. The eval disqualifies for garbage collection if it or its
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// allocs are not older than the threshold. If the eval should be garbage
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// collected, the associated alloc ids that should also be removed are also
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// returned
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func (c *CoreScheduler) gcEval(eval *structs.Evaluation, thresholdIndex uint64, allowBatch bool) (
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bool, []string, error) {
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// Ignore non-terminal and new evaluations
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if !eval.TerminalStatus() || eval.ModifyIndex > thresholdIndex {
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return false, nil, nil
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}
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// Create a watchset
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ws := memdb.NewWatchSet()
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// If the eval is from a running "batch" job we don't want to garbage
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// collect its allocations. If there is a long running batch job and its
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// terminal allocations get GC'd the scheduler would re-run the
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// allocations.
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if eval.Type == structs.JobTypeBatch {
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// Check if the job is running
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job, err := c.snap.JobByID(ws, eval.JobID)
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if err != nil {
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return false, nil, err
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}
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// We don't want to gc anything related to a job which is not dead
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// If the batch job doesn't exist we can GC it regardless of allowBatch
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if job != nil && (!allowBatch || job.Status != structs.JobStatusDead) {
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return false, nil, nil
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}
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}
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// Get the allocations by eval
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allocs, err := c.snap.AllocsByEval(ws, eval.ID)
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if err != nil {
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c.srv.logger.Printf("[ERR] sched.core: failed to get allocs for eval %s: %v",
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eval.ID, err)
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return false, nil, err
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}
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// Scan the allocations to ensure they are terminal and old
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gcEval := true
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var gcAllocIDs []string
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for _, alloc := range allocs {
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if !alloc.TerminalStatus() || alloc.ModifyIndex > thresholdIndex {
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// Can't GC the evaluation since not all of the allocations are
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// terminal
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gcEval = false
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} else {
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// The allocation is eligible to be GC'd
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gcAllocIDs = append(gcAllocIDs, alloc.ID)
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}
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}
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return gcEval, gcAllocIDs, nil
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}
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// evalReap contacts the leader and issues a reap on the passed evals and
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// allocs.
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func (c *CoreScheduler) evalReap(evals, allocs []string) error {
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// Call to the leader to issue the reap
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for _, req := range c.partitionReap(evals, allocs) {
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var resp structs.GenericResponse
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if err := c.srv.RPC("Eval.Reap", req, &resp); err != nil {
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c.srv.logger.Printf("[ERR] sched.core: eval reap failed: %v", err)
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return err
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}
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}
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return nil
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}
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// partitionReap returns a list of EvalDeleteRequest to make, ensuring a single
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// request does not contain too many allocations and evaluations. This is
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// necessary to ensure that the Raft transaction does not become too large.
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func (c *CoreScheduler) partitionReap(evals, allocs []string) []*structs.EvalDeleteRequest {
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var requests []*structs.EvalDeleteRequest
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submittedEvals, submittedAllocs := 0, 0
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for submittedEvals != len(evals) || submittedAllocs != len(allocs) {
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req := &structs.EvalDeleteRequest{
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WriteRequest: structs.WriteRequest{
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Region: c.srv.config.Region,
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},
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}
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requests = append(requests, req)
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available := maxIdsPerReap
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// Add the allocs first
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if remaining := len(allocs) - submittedAllocs; remaining > 0 {
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if remaining <= available {
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req.Allocs = allocs[submittedAllocs:]
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available -= remaining
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submittedAllocs += remaining
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} else {
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req.Allocs = allocs[submittedAllocs : submittedAllocs+available]
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submittedAllocs += available
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// Exhausted space so skip adding evals
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continue
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}
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}
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// Add the evals
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if remaining := len(evals) - submittedEvals; remaining > 0 {
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if remaining <= available {
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req.Evals = evals[submittedEvals:]
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submittedEvals += remaining
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} else {
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req.Evals = evals[submittedEvals : submittedEvals+available]
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submittedEvals += available
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}
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}
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}
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return requests
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}
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// nodeGC is used to garbage collect old nodes
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func (c *CoreScheduler) nodeGC(eval *structs.Evaluation) error {
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// Iterate over the evaluations
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ws := memdb.NewWatchSet()
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iter, err := c.snap.Nodes(ws)
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if err != nil {
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return err
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}
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var oldThreshold uint64
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if eval.JobID == structs.CoreJobForceGC {
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// The GC was forced, so set the threshold to its maximum so everything
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// will GC.
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oldThreshold = math.MaxUint64
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c.srv.logger.Println("[DEBUG] sched.core: forced node GC")
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} else {
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// Compute the old threshold limit for GC using the FSM
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// time table. This is a rough mapping of a time to the
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// Raft index it belongs to.
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tt := c.srv.fsm.TimeTable()
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cutoff := time.Now().UTC().Add(-1 * c.srv.config.NodeGCThreshold)
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oldThreshold = tt.NearestIndex(cutoff)
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c.srv.logger.Printf("[DEBUG] sched.core: node GC: scanning before index %d (%v)",
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oldThreshold, c.srv.config.NodeGCThreshold)
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}
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// Collect the nodes to GC
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var gcNode []string
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OUTER:
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for {
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raw := iter.Next()
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if raw == nil {
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break
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}
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node := raw.(*structs.Node)
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// Ignore non-terminal and new nodes
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if !node.TerminalStatus() || node.ModifyIndex > oldThreshold {
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continue
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}
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// Get the allocations by node
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ws := memdb.NewWatchSet()
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allocs, err := c.snap.AllocsByNode(ws, node.ID)
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if err != nil {
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c.srv.logger.Printf("[ERR] sched.core: failed to get allocs for node %s: %v",
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eval.ID, err)
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continue
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}
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// If there are any non-terminal allocations, skip the node. If the node
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// is terminal and the allocations are not, the scheduler may not have
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// run yet to transition the allocs on the node to terminal. We delay
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// GC'ing until this happens.
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for _, alloc := range allocs {
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if !alloc.TerminalStatus() {
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continue OUTER
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}
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}
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// Node is eligible for garbage collection
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gcNode = append(gcNode, node.ID)
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}
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// Fast-path the nothing case
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if len(gcNode) == 0 {
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return nil
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}
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c.srv.logger.Printf("[DEBUG] sched.core: node GC: %d nodes eligible", len(gcNode))
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// Call to the leader to issue the reap
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for _, nodeID := range gcNode {
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req := structs.NodeDeregisterRequest{
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NodeID: nodeID,
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WriteRequest: structs.WriteRequest{
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Region: c.srv.config.Region,
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},
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}
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var resp structs.NodeUpdateResponse
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if err := c.srv.RPC("Node.Deregister", &req, &resp); err != nil {
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c.srv.logger.Printf("[ERR] sched.core: node '%s' reap failed: %v", nodeID, err)
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return err
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}
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}
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return nil
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}
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