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jobs: use low-priority transactions for claim, adopt, cancel/pause #65643

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merged 1 commit into from
May 25, 2021
Merged

jobs: use low-priority transactions for claim, adopt, cancel/pause #65643

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11 changes: 11 additions & 0 deletions pkg/jobs/adopt.go
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@ import (

"github.com/cockroachdb/cockroach/pkg/jobs/jobspb"
"github.com/cockroachdb/cockroach/pkg/kv"
"github.com/cockroachdb/cockroach/pkg/roachpb"
"github.com/cockroachdb/cockroach/pkg/security"
"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
"github.com/cockroachdb/cockroach/pkg/sql/sessiondata"
Expand Down Expand Up @@ -47,6 +48,11 @@ const (
// available.
func (r *Registry) claimJobs(ctx context.Context, s sqlliveness.Session) error {
return r.db.Txn(ctx, func(ctx context.Context, txn *kv.Txn) error {
// Run the claim transaction at low priority to ensure that it does not
// contend with foreground reads.
if err := txn.SetUserPriority(roachpb.MinUserPriority); err != nil {
return errors.WithAssertionFailure(err)
}
numRows, err := r.ex.Exec(
ctx, "claim-jobs", txn, `
UPDATE system.jobs
Expand Down Expand Up @@ -283,6 +289,11 @@ func (r *Registry) runJob(

func (r *Registry) servePauseAndCancelRequests(ctx context.Context, s sqlliveness.Session) error {
return r.db.Txn(ctx, func(ctx context.Context, txn *kv.Txn) error {
// Run the claim transaction at low priority to ensure that it does not
// contend with foreground reads.
if err := txn.SetUserPriority(roachpb.MinUserPriority); err != nil {
return errors.WithAssertionFailure(err)
}
// Note that we have to buffer all rows first - before processing each
// job - because we have to make sure that the query executes without an
// error (otherwise, the system.jobs table might diverge from the jobs
Expand Down
20 changes: 15 additions & 5 deletions pkg/jobs/registry.go
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ import (
"github.com/cockroachdb/cockroach/pkg/base"
"github.com/cockroachdb/cockroach/pkg/jobs/jobspb"
"github.com/cockroachdb/cockroach/pkg/kv"
"github.com/cockroachdb/cockroach/pkg/roachpb"
"github.com/cockroachdb/cockroach/pkg/security"
"github.com/cockroachdb/cockroach/pkg/server/telemetry"
"github.com/cockroachdb/cockroach/pkg/settings"
Expand Down Expand Up @@ -659,16 +660,25 @@ func (r *Registry) Start(
}

removeClaimsFromDeadSessions := func(ctx context.Context, s sqlliveness.Session) {
if _, err := r.ex.QueryRowEx(
ctx, "expire-sessions", nil,
sessiondata.InternalExecutorOverride{User: security.RootUserName()}, `
if err := r.db.Txn(ctx, func(ctx context.Context, txn *kv.Txn) error {
// Run the expiration transaction at low priority to ensure that it does
// not contend with foreground reads. Note that the adoption and cancellation
// queries also use low priority so they will interact nicely.
if err := txn.SetUserPriority(roachpb.MinUserPriority); err != nil {
return errors.WithAssertionFailure(err)
}
_, err := r.ex.ExecEx(
ctx, "expire-sessions", nil,
sessiondata.InternalExecutorOverride{User: security.RootUserName()}, `
UPDATE system.jobs
SET claim_session_id = NULL
WHERE claim_session_id <> $1
AND status IN `+claimableStatusTupleString+`
AND NOT crdb_internal.sql_liveness_is_alive(claim_session_id)`,
s.ID().UnsafeBytes(),
); err != nil {
s.ID().UnsafeBytes(),
)
return err
}); err != nil {
log.Errorf(ctx, "error expiring job sessions: %s", err)
}
}
Expand Down