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Add tracing spans to promql (#4436) 

* Add spans to promql

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>

* Simplify timer and span tracking.

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>
This commit is contained in:
Goutham Veeramachaneni 2018-08-16 13:11:34 +05:30 committed by GitHub
parent 0b4d22b245
commit 71855a22a4
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 93 additions and 29 deletions
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44
promql/engine.go
View File

@ -85,7 +85,7 @@ type Query interface {
// Statement returns the parsed statement of the query.
Statement() Statement
// Stats returns statistics about the lifetime of the query.
Stats() *stats.TimerGroup
Stats() *stats.QueryTimers
// Cancel signals that a running query execution should be aborted.
Cancel()
}
@ -99,7 +99,7 @@ type query struct {
// Statement of the parsed query.
stmt Statement
// Timer stats for the query execution.
stats *stats.TimerGroup
stats *stats.QueryTimers
// Result matrix for reuse.
matrix Matrix
// Cancellation function for the query.
@ -115,7 +115,7 @@ func (q *query) Statement() Statement {
}
// Stats implements the Query interface.
func (q *query) Stats() *stats.TimerGroup {
func (q *query) Stats() *stats.QueryTimers {
return q.stats
}
@ -276,7 +276,7 @@ func (ng *Engine) newQuery(q storage.Queryable, expr Expr, start, end time.Time,
qry := &query{
stmt: es,
ng: ng,
stats: stats.NewTimerGroup(),
stats: stats.NewQueryTimers(),
queryable: q,
}
return qry
@ -294,7 +294,7 @@ func (ng *Engine) newTestQuery(f func(context.Context) error) Query {
q: "test statement",
stmt: testStmt(f),
ng: ng,
stats: stats.NewTimerGroup(),
stats: stats.NewQueryTimers(),
}
return qry
}
@ -310,25 +310,25 @@ func (ng *Engine) exec(ctx context.Context, q *query) (Value, error) {
ctx, cancel := context.WithTimeout(ctx, ng.timeout)
q.cancel = cancel
execTimer := q.stats.GetTimer(stats.ExecTotalTime).Start()
defer execTimer.Stop()
queueTimer := q.stats.GetTimer(stats.ExecQueueTime).Start()
execSpanTimer, ctx := q.stats.GetSpanTimer(ctx, stats.ExecTotalTime)
defer execSpanTimer.Finish()
queueSpanTimer, _ := q.stats.GetSpanTimer(ctx, stats.ExecQueueTime, ng.metrics.queryQueueTime)
if err := ng.gate.Start(ctx); err != nil {
return nil, err
}
defer ng.gate.Done()
queueTimer.Stop()
ng.metrics.queryQueueTime.Observe(queueTimer.ElapsedTime().Seconds())
queueSpanTimer.Finish()
// Cancel when execution is done or an error was raised.
defer q.cancel()
const env = "query execution"
evalTimer := q.stats.GetTimer(stats.EvalTotalTime).Start()
defer evalTimer.Stop()
evalSpanTimer, ctx := q.stats.GetSpanTimer(ctx, stats.EvalTotalTime)
defer evalSpanTimer.Finish()
// The base context might already be canceled on the first iteration (e.g. during shutdown).
if err := contextDone(ctx, env); err != nil {
@ -355,10 +355,9 @@ func durationMilliseconds(d time.Duration) int64 {
// execEvalStmt evaluates the expression of an evaluation statement for the given time range.
func (ng *Engine) execEvalStmt(ctx context.Context, query *query, s *EvalStmt) (Value, error) {
prepareTimer := query.stats.GetTimer(stats.QueryPreparationTime).Start()
querier, err := ng.populateSeries(ctx, query.queryable, s)
prepareTimer.Stop()
ng.metrics.queryPrepareTime.Observe(prepareTimer.ElapsedTime().Seconds())
prepareSpanTimer, ctxPrepare := query.stats.GetSpanTimer(ctx, stats.QueryPreparationTime, ng.metrics.queryPrepareTime)
querier, err := ng.populateSeries(ctxPrepare, query.queryable, s)
prepareSpanTimer.Finish()
// XXX(fabxc): the querier returned by populateSeries might be instantiated
// we must not return without closing irrespective of the error.
@ -371,7 +370,7 @@ func (ng *Engine) execEvalStmt(ctx context.Context, query *query, s *EvalStmt) (
return nil, err
}
evalTimer := query.stats.GetTimer(stats.InnerEvalTime).Start()
evalSpanTimer, _ := query.stats.GetSpanTimer(ctx, stats.InnerEvalTime, ng.metrics.queryInnerEval)
// Instant evaluation. This is executed as a range evaluation with one step.
if s.Start == s.End && s.Interval == 0 {
start := timeMilliseconds(s.Start)
@ -387,8 +386,7 @@ func (ng *Engine) execEvalStmt(ctx context.Context, query *query, s *EvalStmt) (
return nil, err
}
evalTimer.Stop()
ng.metrics.queryInnerEval.Observe(evalTimer.ElapsedTime().Seconds())
evalSpanTimer.Finish()
mat, ok := val.(Matrix)
if !ok {
@ -427,8 +425,7 @@ func (ng *Engine) execEvalStmt(ctx context.Context, query *query, s *EvalStmt) (
if err != nil {
return nil, err
}
evalTimer.Stop()
ng.metrics.queryInnerEval.Observe(evalTimer.ElapsedTime().Seconds())
evalSpanTimer.Finish()
mat, ok := val.(Matrix)
if !ok {
@ -442,11 +439,10 @@ func (ng *Engine) execEvalStmt(ctx context.Context, query *query, s *EvalStmt) (
// TODO(fabxc): order ensured by storage?
// TODO(fabxc): where to ensure metric labels are a copy from the storage internals.
sortTimer := query.stats.GetTimer(stats.ResultSortTime).Start()
sortSpanTimer, _ := query.stats.GetSpanTimer(ctx, stats.ResultSortTime, ng.metrics.queryResultSort)
sort.Sort(mat)
sortTimer.Stop()
sortSpanTimer.Finish()
ng.metrics.queryResultSort.Observe(sortTimer.ElapsedTime().Seconds())
return mat, nil
}

72
util/stats/query_stats.go
View File

@ -13,6 +13,13 @@
package stats
import (
"context"
opentracing "github.com/opentracing/opentracing-go"
"github.com/prometheus/client_golang/prometheus"
)
// QueryTiming identifies the code area or functionality in which time is spent
// during a query.
type QueryTiming int
@ -47,6 +54,26 @@ func (s QueryTiming) String() string {
}
}
// Return a string representation of a QueryTiming span operation.
func (s QueryTiming) SpanOperation() string {
switch s {
case EvalTotalTime:
return "promqlEval"
case ResultSortTime:
return "promqlSort"
case QueryPreparationTime:
return "promqlPrepare"
case InnerEvalTime:
return "promqlInnerEval"
case ExecQueueTime:
return "promqlExecQueue"
case ExecTotalTime:
return "promqlExec"
default:
return "Unknown query timing"
}
}
// queryTimings with all query timers mapped to durations.
type queryTimings struct {
EvalTotalTime float64 `json:"evalTotalTime"`
@ -64,10 +91,10 @@ type QueryStats struct {
// NewQueryStats makes a QueryStats struct with all QueryTimings found in the
// given TimerGroup.
func NewQueryStats(tg *TimerGroup) *QueryStats {
func NewQueryStats(tg *QueryTimers) *QueryStats {
var qt queryTimings
for s, timer := range tg.timers {
for s, timer := range tg.TimerGroup.timers {
switch s {
case EvalTotalTime:
qt.EvalTotalTime = timer.Duration()
@ -87,3 +114,44 @@ func NewQueryStats(tg *TimerGroup) *QueryStats {
qs := QueryStats{Timings: qt}
return &qs
}
// SpanTimer unifies tracing and timing, to reduce repetition.
type SpanTimer struct {
timer *Timer
observers []prometheus.Observer
span opentracing.Span
}
func NewSpanTimer(ctx context.Context, operation string, timer *Timer, observers ...prometheus.Observer) (*SpanTimer, context.Context) {
span, ctx := opentracing.StartSpanFromContext(ctx, operation)
timer.Start()
return &SpanTimer{
timer: timer,
observers: observers,
span: span,
}, ctx
}
func (s *SpanTimer) Finish() {
s.timer.Stop()
s.span.Finish()
for _, obs := range s.observers {
obs.Observe(s.timer.ElapsedTime().Seconds())
}
}
type QueryTimers struct {
*TimerGroup
}
func NewQueryTimers() *QueryTimers {
return &QueryTimers{NewTimerGroup()}
}
func (qs *QueryTimers) GetSpanTimer(ctx context.Context, qt QueryTiming, observers ...prometheus.Observer) (*SpanTimer, context.Context) {
return NewSpanTimer(ctx, qt.SpanOperation(), qs.TimerGroup.GetTimer(qt), observers...)
}

6
util/stats/stats_test.go
View File

@ -39,13 +39,13 @@ func TestTimerGroupNewTimer(t *testing.T) {
}
func TestQueryStatsWithTimers(t *testing.T) {
tg := NewTimerGroup()
timer := tg.GetTimer(ExecTotalTime)
qt := NewQueryTimers()
timer := qt.GetTimer(ExecTotalTime)
timer.Start()
time.Sleep(2 * time.Millisecond)
timer.Stop()
qs := NewQueryStats(tg)
qs := NewQueryStats(qt)
actual, err := json.Marshal(qs)
if err != nil {
t.Fatalf("Unexpected error during serialization: %v", err)