How to support dynamic pool?

Because this repo(envoyproxy/ratelimit) is using mediocregopher/radix to manage redis connection and there has comment as below, e.g.

// Pool is dynamic in that it can create more connections on-the-fly to handle // increased load. The maximum number of extra connections (if any) can be // configured, along with how long they are kept after load has returned to // normal. (https://github.com/mediocregopher/radix/blob/v3/pool.go#L263)

So it seems envoyproxy/ratelimit support dynamaic pool by default.

I deployed this repo with below k8s deployment spec

click here to see the k8s deployment spec

```yaml apiVersion: apps/v1 kind: Deployment metadata: ... labels: kind: ratelimit-service name: test-ratelimit namespace: test-namespace spec: progressDeadlineSeconds: 600 replicas: 1 revisionHistoryLimit: 10 selector: matchLabels: app.kubernetes.io/name: test-ratelimit strategy: rollingUpdate: maxSurge: 25% maxUnavailable: 25% type: RollingUpdate template: metadata: creationTimestamp: null labels: app.kubernetes.io/name: test-ratelimit kind: ratelimit-service spec: containers: - args: - /bin/ratelimit env: - name: LOG_FORMAT value: text - name: LOG_LEVEL value: info - name: DECISION_LOG_SCOPE value: over_limit - name: REDIS_SOCKET_TYPE value: tcp - name: REDIS_TYPE value: cluster - name: REDIS_URL value: xxx.xxx.xxx.xxx:6379,xxx.xxx.xxx.xxx:6379,xxx.xxx.xxx.xxx:6379,xxx.xxx.xxx.xxx:6379 - name: REDIS_POOL_SIZE value: "1" <----------------- this is key config - name: REDIS_AUTH value: xxxx - name: REDIS_TLS value: "false" - name: REDIS_PIPELINE_WINDOW value: 150us - name: REDIS_PIPELINE_LIMIT value: "0" - name: RUNTIME_ROOT value: /data - name: RUNTIME_SUBDIRECTORY value: ratelimit - name: RUNTIME_IGNOREDOTFILES value: "true" - name: RUNTIME_WATCH_ROOT value: "false" - name: LOCAL_CACHE_SIZE_IN_BYTES value: "1048576" - name: CACHE_KEY_PREFIX value: test-prefix_ - name: USE_STATSD value: "true" image: ratelimit:tag # this repo's image i built imagePullPolicy: IfNotPresent lifecycle: preStop: exec: command: - /bin/sleep - "10" livenessProbe: failureThreshold: 3 httpGet: path: / port: debug scheme: HTTP initialDelaySeconds: 15 periodSeconds: 10 successThreshold: 1 timeoutSeconds: 1 name: ratelimit-service ports: - containerPort: 8080 name: json protocol: TCP - containerPort: 8081 name: rpc protocol: TCP - containerPort: 6070 name: debug protocol: TCP - containerPort: 9102 name: rl-metrics protocol: TCP readinessProbe: failureThreshold: 3 httpGet: path: / port: debug scheme: HTTP initialDelaySeconds: 15 periodSeconds: 10 successThreshold: 1 timeoutSeconds: 1 resources: limits: cpu: "4" memory: 2Gi requests: cpu: "0" memory: 128Mi terminationMessagePath: /dev/termination-log terminationMessagePolicy: File volumeMounts: - mountPath: /data/ratelimit/config name: rl-configs dnsPolicy: ClusterFirst restartPolicy: Always schedulerName: default-scheduler securityContext: {} terminationGracePeriodSeconds: 30 volumes: - configMap: defaultMode: 420 name: ratelimit-cm name: rl-configs - configMap: defaultMode: 420 name: ratelimit-st-cm name: st-configs ```

After deployed successfully, i did below test, it seems dynamic pool is not supported Test result as below

RPS	ratelimit pod number	REDIS_POOL_SIZE	active connections number	total connections number	429 requests ratio
0	1	1	4	4	N/A
5000	1	1	4	4	100%
10000	1	1	4	4	99.9%
15000	1	1	4	4	34% sometimes ratelimit pod crashed
20000	1	1	4 before pod crash, this value was not changed	4	ratelimit pod crashed

(active connections number can be got from cx_active metric, total connections number can be got from cx_total metric)

I have two questions.

from above test, it seems new connections are not created under higher RPS, there has any method that make the connection created automatically under higher RPS?
It seems there has any relation between REDIS_POOL_SIZE and active connections number, e.g.
```
active connections number = REDIS_POOL_SIZE * 4
```
someone knows the reason?

envoyproxy / ratelimit

How to support dynamic pool? #714