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release-24.3: spanlatch: add cluster setting for slow latch request threshold #160036

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release-24.3: spanlatch: add cluster setting for slow latch request threshold #160036

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1 change: 0 additions & 1 deletion pkg/kv/kvserver/spanlatch/BUILD.bazel
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,6 @@ go_library(
importpath = "github.com/cockroachdb/cockroach/pkg/kv/kvserver/spanlatch",
visibility = ["//visibility:public"],
deps = [
"//pkg/base",
"//pkg/kv/kvpb",
"//pkg/kv/kvserver/concurrency/poison",
"//pkg/kv/kvserver/spanset",
Expand Down
15 changes: 12 additions & 3 deletions pkg/kv/kvserver/spanlatch/manager.go
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Expand Up @@ -11,7 +11,6 @@ import (
"time"
"unsafe"

"github.com/cockroachdb/cockroach/pkg/base"
"github.com/cockroachdb/cockroach/pkg/kv/kvpb"
"github.com/cockroachdb/cockroach/pkg/kv/kvserver/concurrency/poison"
"github.com/cockroachdb/cockroach/pkg/kv/kvserver/spanset"
Expand Down Expand Up @@ -579,7 +578,9 @@ func (m *Manager) waitForSignal(
}()
log.Eventf(ctx, "waiting to acquire %s latch %s, held by %s latch %s", waitType, wait, heldType, held)
poisonCh := held.g.poison.signalChan()
t.Reset(base.SlowRequestThreshold)

slowThreshold := m.slowLatchRequestThreshold()
t.Reset(slowThreshold)
for {
select {
case <-held.g.done.signalChan():
Expand All @@ -604,7 +605,7 @@ func (m *Manager) waitForSignal(
t.Read = true

log.Warningf(ctx, "have been waiting %s to acquire %s latch %s, held by %s latch %s",
base.SlowRequestThreshold, waitType, wait, heldType, held)
slowThreshold, waitType, wait, heldType, held)
if m.slowReqs != nil {
m.slowReqs.Inc(1)
defer m.slowReqs.Dec(1)
Expand Down Expand Up @@ -682,6 +683,14 @@ func (m *Manager) longLatchHoldThreshold() time.Duration {
return LongLatchHoldThreshold.Get(&m.settings.SV)
}

// slowLatchRequestThreshold returns the threshold for logging slow latch requests.
func (m *Manager) slowLatchRequestThreshold() time.Duration {
if m.settings == nil {
return math.MaxInt64 // disable
}
return SlowLatchRequestThreshold.Get(&m.settings.SV)
}

// Metrics holds information about the state of a Manager.
type Metrics struct {
ReadCount int64
Expand Down
11 changes: 11 additions & 0 deletions pkg/kv/kvserver/spanlatch/settings.go
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Expand Up @@ -23,3 +23,14 @@ var LongLatchHoldThreshold = settings.RegisterDurationSetting(
3*time.Second,
settings.NonNegativeDuration,
)

// SlowLatchRequestThreshold controls when we will log slow latch acquisition
// attempts. When a latch acquisition has been waiting for this duration, a
// warning is logged and the slow request metric is incremented.
var SlowLatchRequestThreshold = settings.RegisterDurationSettingWithExplicitUnit(
settings.SystemOnly,
"kv.concurrency.slow_latch_request_duration",
"the threshold for logging slow latch acquisition attempts",
5*time.Second,
settings.DurationWithMinimum(10*time.Millisecond),
)