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lib/promscrape/discovery/kubernetes: reduce memory usage further when big number of scrape jobs are configured for the same kubernetes_sd_config role

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Serialize reloading per-role objects, so they don't occupy too much memory when objects for many scrape jobs are simultaneously refreshed.
Do not reload per-role objects if they were already refreshed by concurrent goroutines. This should reduce load on Kubernetes API server
when big number of scrape jobs are configured for the same Kubernetes role.

This is a follow-up for 17b87725ed

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1113
This commit is contained in:
Aliaksandr Valialkin 2021-03-07 19:50:01 +02:00
parent 175466bb41
commit c04505e585
1 changed files with 45 additions and 11 deletions
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52
lib/promscrape/discovery/kubernetes/api_watcher.go
View file

@ -155,12 +155,12 @@ func (aw *apiWatcher) startWatcherForURL(role, apiURL string, parseObject parseO
uw.watchersCount.Inc()
uw.watchersCreated.Inc()
resourceVersion := uw.reloadObjects()
uw.reloadObjects()
aw.wg.Add(1)
go func() {
defer aw.wg.Done()
logger.Infof("started watcher for %q", apiURL)
uw.watchForUpdates(resourceVersion)
uw.watchForUpdates()
logger.Infof("stopped watcher for %q", apiURL)
uw.objectsByKey.decRef()
@ -205,9 +205,10 @@ type urlWatcher struct {
// objectsByKey contains the latest state for objects obtained from apiURL
objectsByKey *objectsMap
// mu protects swosByKey
// mu protects swosByKey and resourceVersion
mu sync.Mutex
swosByKey map[string][]interface{}
resourceVersion string
// the parent apiWatcher
aw *apiWatcher
@ -236,8 +237,38 @@ func (aw *apiWatcher) newURLWatcher(role, apiURL string, parseObject parseObject
}
}
// Limit the concurrency for per-role objects reloading to 1.
//
// This should reduce memory usage when big number of watchers simultaneously receive an update for objects of the same role.
var reloadObjectsLocksByRole = map[string]*sync.Mutex{
"node": {},
"pod": {},
"service": {},
"endpoints": {},
"endpointslices": {},
"ingress": {},
}
func (uw *urlWatcher) resetResourceVersion() {
uw.mu.Lock()
uw.resourceVersion = ""
uw.mu.Unlock()
}
// reloadObjects reloads objects to the latest state and returns resourceVersion for the latest state.
func (uw *urlWatcher) reloadObjects() string {
lock := reloadObjectsLocksByRole[uw.role]
lock.Lock()
defer lock.Unlock()
uw.mu.Lock()
resourceVersion := uw.resourceVersion
uw.mu.Unlock()
if resourceVersion != "" {
// Fast path - objects have been already reloaded by concurrent goroutines.
return resourceVersion
}
aw := uw.aw
requestURL := uw.apiURL
resp, err := aw.doRequest(requestURL)
@ -261,7 +292,7 @@ func (uw *urlWatcher) reloadObjects() string {
return ""
}
uw.objectsByKey.reload(objectsByKey)
swosByKey := make(map[string][]interface{}, len(objectsByKey))
swosByKey := make(map[string][]interface{})
for k, o := range objectsByKey {
labels := o.getTargetLabels(aw)
swos := getScrapeWorkObjectsForLabels(aw.swcFunc, labels)
@ -271,7 +302,9 @@ func (uw *urlWatcher) reloadObjects() string {
}
uw.mu.Lock()
uw.swosByKey = swosByKey
uw.resourceVersion = metadata.ResourceVersion
uw.mu.Unlock()
return metadata.ResourceVersion
}
@ -287,10 +320,10 @@ func getScrapeWorkObjectsForLabels(swcFunc ScrapeWorkConstructorFunc, labelss []
return swos
}
// watchForUpdates watches for object updates starting from resourceVersion and updates the corresponding objects to the latest state.
// watchForUpdates watches for object updates starting from uw.resourceVersion and updates the corresponding objects to the latest state.
//
// See https://kubernetes.io/docs/reference/using-api/api-concepts/#efficient-detection-of-changes
func (uw *urlWatcher) watchForUpdates(resourceVersion string) {
func (uw *urlWatcher) watchForUpdates() {
aw := uw.aw
backoffDelay := time.Second
maxBackoffDelay := 30 * time.Second
@ -312,6 +345,7 @@ func (uw *urlWatcher) watchForUpdates(resourceVersion string) {
if aw.needStop() {
return
}
resourceVersion := uw.reloadObjects()
requestURL := apiURL
if resourceVersion != "" {
requestURL += "&resourceVersion=" + url.QueryEscape(resourceVersion)
@ -323,7 +357,7 @@ func (uw *urlWatcher) watchForUpdates(resourceVersion string) {
}
logger.Errorf("error when performing a request to %q: %s", requestURL, err)
backoffSleep()
resourceVersion = uw.reloadObjects()
uw.resetResourceVersion()
continue
}
if resp.StatusCode != http.StatusOK {
@ -336,7 +370,7 @@ func (uw *urlWatcher) watchForUpdates(resourceVersion string) {
} else {
backoffSleep()
}
resourceVersion = uw.reloadObjects()
uw.resetResourceVersion()
continue
}
backoffDelay = time.Second
@ -350,7 +384,7 @@ func (uw *urlWatcher) watchForUpdates(resourceVersion string) {
logger.Errorf("error when reading WatchEvent stream from %q: %s", requestURL, err)
}
backoffSleep()
resourceVersion = uw.reloadObjects()
uw.resetResourceVersion()
continue
}
}