Change:
store.updateCache(add) } } <ins> func TestHistogramCacheReadWait(t *testing.T) { registry := k8smetrics.NewKubeRegistry() if err := registry.Register(metrics.WatchCacheReadWait); err != nil { t.Errorf("unexpected error: %v", err) } ctx := context.Background() testedMetrics := "apiserver_watch_cache_read_wait_seconds" store := newTestWatchCache(2, &cache.Indexers{}) defer store.Stop() // In background, update the store. go func() { if err := store.Add(makeTestPod("foo", 2)); err != nil { t.Errorf("unexpected error: %v", err) } if err := store.Add(makeTestPod("bar", 5)); err != nil { t.Errorf("unexpected error: %v", err) } }() testCases := []struct { desc            string resourceVersion uint64 want            string }{ { desc:            "resourceVersion is non-zero", resourceVersion: 5, want: ` # HELP apiserver_watch_cache_read_wait_seconds [ALPHA] Histogram of time spent waiting for a watch cache to become fresh. # TYPE apiserver_watch_cache_read_wait_seconds histogram apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="0.005"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="0.025"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="0.05"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="0.1"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="0.2"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="0.4"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="0.6"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="0.8"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="1"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="1.25"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="1.5"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="2"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="3"} 1 apiserver_watch_cache_read_wait_seconds_bucket{resource="pods",le="+Inf"} 1 apiserver_watch_cache_read_wait_seconds_sum{resource="pods"} 0 apiserver_watch_cache_read_wait_seconds_count{resource="pods"} 1 `, }, { desc:            "resourceVersion is 0", resourceVersion: 0, want:            ``, }, } for _, test := range testCases { t.Run(test.desc, func(t *testing.T) { defer registry.Reset() if _, _, _, err := store.WaitUntilFreshAndGet(ctx, test.resourceVersion, "prefix/ns/bar"); err != nil { t.Errorf("unexpected error: %v", err) } if err := testutil.GatherAndCompare(registry, strings.NewReader(test.want), testedMetrics); err != nil { t.Errorf("unexpected error: %v", err) } }) } } </ins>

Discussion:
Part of From For now posted as a "help wanted" issue, however if we cannot hit the timeline for 1.30 code freeze () I would take it over so we don't miss. Still issue is simple enough that it can be quickly implemented. Implementation tips: Add a metric around waitUnitlFreshAndBlock method Metric should be a histogram with latency buckets similar to api latency Metric should have label for resource version. A way to monitor watch cache impact on request latency.
/sig api-machinery /triage accepted /help
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