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embedded cache: update metric namespace and remove duplicate metrics #10693

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merged 5 commits into from
Sep 29, 2023
Merged

embedded cache: update metric namespace and remove duplicate metrics #10693

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a008977
rename embedded cache metrics
ashwanthgoli Sep 25, 2023
bacd9d8
remove metrics already covered by cache/instrumented.go
ashwanthgoli Sep 25, 2023
6a07988
add docs
ashwanthgoli Sep 25, 2023
b544e27
add changelog entry
ashwanthgoli Sep 25, 2023
4c3e8f5
fix integration test
ashwanthgoli Sep 28, 2023
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -19,6 +19,7 @@
* [10534](https://github.com/grafana/loki/pull/10534) **chaudum** Remove configuration `use_boltdb_shipper_as_backup`
* [10620](https://github.com/grafana/loki/pull/10620) **ashwanthgoli** Enable embedded cache if no other cache is explicitly enabled.
* [10655](https://github.com/grafana/loki/pull/10655) **chaudum** Remove legacy ingester shutdown handler `/ingester/flush_shutdown`.
* [10693](https://github.com/grafana/loki/pull/10693) **ashwanthgoli** Embedded cache: Updates the metric prefix from `querier_cache_` to `loki_embeddedcache_` and removes duplicate metrics.

##### Fixes

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15 changes: 15 additions & 0 deletions docs/sources/setup/upgrade/_index.md
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Expand Up @@ -69,6 +69,21 @@ This new metric will provide a more clear signal that there is an issue with ing

1. `frontend.embedded-cache.max-size-mb` Embedded results cache size now defaults to 100MB.

#### Embedded cache metric changes

- The following embedded cache metrics are removed. Instead use `loki_cache_fetched_keys`, `loki_cache_hits`, `loki_cache_request_duration_seconds` which instruments requests made to the configured cache (`embeddedcache`, `memcached` or `redis`).
- `querier_cache_added_total`
- `querier_cache_gets_total`
- `querier_cache_misses_total`
Comment on lines +74 to +77
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If these are a one-to-one replacement, to avoid confusion I'd list them next to the parameter they're replacing. (If they aren't a one-to-one replacement, then ignore this suggestion!)

Suggested change
- The following embedded cache metrics are removed. Instead use `loki_cache_fetched_keys`, `loki_cache_hits`, `loki_cache_request_duration_seconds` which instruments requests made to the configured cache (`embeddedcache`, `memcached` or `redis`).
- `querier_cache_added_total`
- `querier_cache_gets_total`
- `querier_cache_misses_total`
- The following embedded cache metrics are removed. Instead use the new metrics, which instrument requests made to the configured cache (`embeddedcache`, `memcached` or `redis`).
- `querier_cache_added_total` instead use `loki_cache_fetched_keys`
- `querier_cache_gets_total` instead use `loki_cache_hits`
- `querier_cache_misses_total` instead use `loki_cache_request_duration_seconds`


- The following embedded cache metrics are renamed:
- `querier_cache_added_new_total` is renamed to `loki_embeddedcache_added_new_total`
- `querier_cache_evicted_total` is renamed to `loki_embeddedcache_evicted_total`
- `querier_cache_entries` is renamed to `loki_embeddedcache_entries`
- `querier_cache_memory_bytes` is renamed to `loki_embeddedcache_memory_bytes`

- Already deprecated metric `querier_cache_stale_gets_total` is now removed.

## 2.9.0

### Loki
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15 changes: 11 additions & 4 deletions integration/loki_micro_services_test.go
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Expand Up @@ -734,17 +734,24 @@ func assertCacheState(t *testing.T, metrics string, e *expectedCacheState) {
},
}

mf, found := mfs["querier_cache_added_new_total"]
mf, found := mfs["loki_embeddedcache_added_new_total"]
require.True(t, found)
require.Equal(t, e.added, getValueFromMF(mf, lbs))

mf, found = mfs["querier_cache_gets_total"]
lbs = []*dto.LabelPair{
{
Name: proto.String("name"),
Value: proto.String(e.cacheName),
},
}

mf, found = mfs["loki_cache_fetched_keys"]
require.True(t, found)
require.Equal(t, e.gets, getValueFromMF(mf, lbs))

mf, found = mfs["querier_cache_misses_total"]
mf, found = mfs["loki_cache_hits"]
require.True(t, found)
require.Equal(t, e.misses, getValueFromMF(mf, lbs))
require.Equal(t, e.gets-e.misses, getValueFromMF(mf, lbs))
}

type expectedCacheState struct {
Expand Down
59 changes: 9 additions & 50 deletions pkg/storage/chunk/cache/embeddedcache.go
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Expand Up @@ -47,13 +47,9 @@ type EmbeddedCache struct {

done chan struct{}

entriesAdded prometheus.Counter
entriesAddedNew prometheus.Counter
entriesEvicted *prometheus.CounterVec
entriesCurrent prometheus.Gauge
totalGets prometheus.Counter
totalMisses prometheus.Counter
staleGets prometheus.Counter
memoryBytes prometheus.Gauge
}

Expand Down Expand Up @@ -110,65 +106,33 @@ func NewEmbeddedCache(name string, cfg EmbeddedCacheConfig, reg prometheus.Regis

done: make(chan struct{}),

entriesAdded: promauto.With(reg).NewCounter(prometheus.CounterOpts{
Namespace: "querier",
Subsystem: "cache",
Name: "added_total",
Help: "The total number of Put calls on the cache",
ConstLabels: prometheus.Labels{"cache": name},
}),

entriesAddedNew: promauto.With(reg).NewCounter(prometheus.CounterOpts{
Namespace: "querier",
Subsystem: "cache",
Namespace: "loki",
Subsystem: "embeddedcache",
Name: "added_new_total",
Help: "The total number of new entries added to the cache",
ConstLabels: prometheus.Labels{"cache": name},
}),

entriesEvicted: promauto.With(reg).NewCounterVec(prometheus.CounterOpts{
Namespace: "querier",
Subsystem: "cache",
Namespace: "loki",
Subsystem: "embeddedcache",
Name: "evicted_total",
Help: "The total number of evicted entries",
ConstLabels: prometheus.Labels{"cache": name},
}, []string{"reason"}),

entriesCurrent: promauto.With(reg).NewGauge(prometheus.GaugeOpts{
Namespace: "querier",
Subsystem: "cache",
Namespace: "loki",
Subsystem: "embeddedcache",
Name: "entries",
Help: "The total number of entries",
ConstLabels: prometheus.Labels{"cache": name},
}),

totalGets: promauto.With(reg).NewCounter(prometheus.CounterOpts{
Namespace: "querier",
Subsystem: "cache",
Name: "gets_total",
Help: "The total number of Get calls",
ConstLabels: prometheus.Labels{"cache": name},
}),

totalMisses: promauto.With(reg).NewCounter(prometheus.CounterOpts{
Namespace: "querier",
Subsystem: "cache",
Name: "misses_total",
Help: "The total number of Get calls that had no valid entry",
ConstLabels: prometheus.Labels{"cache": name},
}),

staleGets: promauto.With(reg).NewCounter(prometheus.CounterOpts{
Namespace: "querier",
Subsystem: "cache",
Name: "stale_gets_total",
Help: "The total number of Get calls that had an entry which expired (deprecated)",
Help: "Current number of entries in the cache",
ConstLabels: prometheus.Labels{"cache": name},
}),

memoryBytes: promauto.With(reg).NewGauge(prometheus.GaugeOpts{
Namespace: "querier",
Subsystem: "cache",
Namespace: "loki",
Subsystem: "embeddedcache",
Name: "memory_bytes",
Help: "The current cache size in bytes",
ConstLabels: prometheus.Labels{"cache": name},
Expand Down Expand Up @@ -231,8 +195,6 @@ func (c *EmbeddedCache) Fetch(ctx context.Context, keys []string) (found []strin

// Store implements Cache.
func (c *EmbeddedCache) Store(_ context.Context, keys []string, values [][]byte) error {
c.entriesAdded.Inc()

c.lock.Lock()
defer c.lock.Unlock()

Expand Down Expand Up @@ -314,8 +276,6 @@ func (c *EmbeddedCache) put(key string, value []byte) {

// Get returns the stored value against the key and when the key was last updated.
func (c *EmbeddedCache) Get(_ context.Context, key string) ([]byte, bool) {
c.totalGets.Inc()

c.lock.RLock()
defer c.lock.RUnlock()

Expand All @@ -325,7 +285,6 @@ func (c *EmbeddedCache) Get(_ context.Context, key string) ([]byte, bool) {
return entry.value, true
}

c.totalMisses.Inc()
return nil, false
}

Expand Down
21 changes: 0 additions & 21 deletions pkg/storage/chunk/cache/embeddedcache_test.go
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Expand Up @@ -64,14 +64,11 @@ func TestEmbeddedCacheEviction(t *testing.T) {

reason := fullReason

assert.Equal(t, testutil.ToFloat64(c.entriesAdded), float64(1))
assert.Equal(t, testutil.ToFloat64(c.entriesAddedNew), float64(cnt))
assert.Equal(t, testutil.ToFloat64(c.entriesEvicted.WithLabelValues(reason)), float64(0))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(cnt))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(len(c.entries)))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(c.lru.Len()))
assert.Equal(t, testutil.ToFloat64(c.totalGets), float64(0))
assert.Equal(t, testutil.ToFloat64(c.totalMisses), float64(0))
assert.Equal(t, testutil.ToFloat64(c.memoryBytes), float64(cnt*sizeOf(itemTemplate)))

for i := 0; i < cnt; i++ {
Expand All @@ -81,14 +78,11 @@ func TestEmbeddedCacheEviction(t *testing.T) {
require.Equal(t, []byte(key), value)
}

assert.Equal(t, testutil.ToFloat64(c.entriesAdded), float64(1))
assert.Equal(t, testutil.ToFloat64(c.entriesAddedNew), float64(cnt))
assert.Equal(t, testutil.ToFloat64(c.entriesEvicted), float64(0))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(cnt))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(len(c.entries)))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(c.lru.Len()))
assert.Equal(t, testutil.ToFloat64(c.totalGets), float64(cnt))
assert.Equal(t, testutil.ToFloat64(c.totalMisses), float64(0))
assert.Equal(t, testutil.ToFloat64(c.memoryBytes), float64(cnt*sizeOf(itemTemplate)))

// Check evictions
Expand All @@ -105,14 +99,11 @@ func TestEmbeddedCacheEviction(t *testing.T) {
require.NoError(t, err)
require.Len(t, c.entries, cnt)

assert.Equal(t, testutil.ToFloat64(c.entriesAdded), float64(2))
assert.Equal(t, testutil.ToFloat64(c.entriesAddedNew), float64(cnt+evicted))
assert.Equal(t, testutil.ToFloat64(c.entriesEvicted.WithLabelValues(reason)), float64(evicted))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(cnt))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(len(c.entries)))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(c.lru.Len()))
assert.Equal(t, testutil.ToFloat64(c.totalGets), float64(cnt))
assert.Equal(t, testutil.ToFloat64(c.totalMisses), float64(0))
assert.Equal(t, testutil.ToFloat64(c.memoryBytes), float64(cnt*sizeOf(itemTemplate)))

for i := 0; i < cnt-evicted; i++ {
Expand All @@ -126,14 +117,11 @@ func TestEmbeddedCacheEviction(t *testing.T) {
require.Equal(t, []byte(key), value)
}

assert.Equal(t, testutil.ToFloat64(c.entriesAdded), float64(2))
assert.Equal(t, testutil.ToFloat64(c.entriesAddedNew), float64(cnt+evicted))
assert.Equal(t, testutil.ToFloat64(c.entriesEvicted.WithLabelValues(reason)), float64(evicted))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(cnt))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(len(c.entries)))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(c.lru.Len()))
assert.Equal(t, testutil.ToFloat64(c.totalGets), float64(cnt*2+evicted))
assert.Equal(t, testutil.ToFloat64(c.totalMisses), float64(cnt-evicted))
assert.Equal(t, testutil.ToFloat64(c.memoryBytes), float64(cnt*sizeOf(itemTemplate)))

// Check updates work
Expand All @@ -156,14 +144,11 @@ func TestEmbeddedCacheEviction(t *testing.T) {
require.Equal(t, []byte(fmt.Sprintf("%02d", i*2)), value)
}

assert.Equal(t, testutil.ToFloat64(c.entriesAdded), float64(3))
assert.Equal(t, testutil.ToFloat64(c.entriesAddedNew), float64(cnt+evicted))
assert.Equal(t, testutil.ToFloat64(c.entriesEvicted.WithLabelValues(reason)), float64(evicted))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(cnt))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(len(c.entries)))
assert.Equal(t, testutil.ToFloat64(c.entriesCurrent), float64(c.lru.Len()))
assert.Equal(t, testutil.ToFloat64(c.totalGets), float64(cnt*2+evicted*2))
assert.Equal(t, testutil.ToFloat64(c.totalMisses), float64(cnt-evicted))
assert.Equal(t, testutil.ToFloat64(c.memoryBytes), float64(cnt*sizeOf(itemTemplate)))

c.Stop()
Expand Down Expand Up @@ -197,31 +182,25 @@ func TestEmbeddedCacheExpiry(t *testing.T) {
_, ok = c.Get(ctx, key1)
require.False(t, ok)

assert.Equal(t, float64(1), testutil.ToFloat64(c.entriesAdded))
assert.Equal(t, float64(4), testutil.ToFloat64(c.entriesAddedNew))
assert.Equal(t, float64(0), testutil.ToFloat64(c.entriesEvicted.WithLabelValues(expiredReason)))
assert.Equal(t, float64(1), testutil.ToFloat64(c.entriesEvicted.WithLabelValues(fullReason)))
assert.Equal(t, float64(3), testutil.ToFloat64(c.entriesCurrent))
assert.Equal(t, float64(len(c.entries)), testutil.ToFloat64(c.entriesCurrent))
assert.Equal(t, float64(c.lru.Len()), testutil.ToFloat64(c.entriesCurrent))
assert.Equal(t, float64(2), testutil.ToFloat64(c.totalGets))
assert.Equal(t, float64(1), testutil.ToFloat64(c.totalMisses))
assert.Equal(t, float64(memorySz), testutil.ToFloat64(c.memoryBytes))

// Expire the item.
time.Sleep(2 * cfg.TTL)
_, ok = c.Get(ctx, key4)
require.False(t, ok)

assert.Equal(t, float64(1), testutil.ToFloat64(c.entriesAdded))
assert.Equal(t, float64(4), testutil.ToFloat64(c.entriesAddedNew))
assert.Equal(t, float64(3), testutil.ToFloat64(c.entriesEvicted.WithLabelValues(expiredReason)))
assert.Equal(t, float64(1), testutil.ToFloat64(c.entriesEvicted.WithLabelValues(fullReason)))
assert.Equal(t, float64(0), testutil.ToFloat64(c.entriesCurrent))
assert.Equal(t, float64(len(c.entries)), testutil.ToFloat64(c.entriesCurrent))
assert.Equal(t, float64(c.lru.Len()), testutil.ToFloat64(c.entriesCurrent))
assert.Equal(t, float64(3), testutil.ToFloat64(c.totalGets))
assert.Equal(t, float64(2), testutil.ToFloat64(c.totalMisses))
assert.Equal(t, float64(memorySz), testutil.ToFloat64(c.memoryBytes))

c.Stop()
Expand Down