bug: apisix report duplicate metrics

[FeiYing9]

Current Behavior

there are several k8s clusters running with apisix, but just one cluster (prod cluster) with the problem that apisix report lots of duplicate metrics.

for example:

apisix_http_status{code="200",route="3fb9d6c2",matched_uri="/api/v1/*",matched_host="xxx",service="",consumer="",node="10.244.19.254",host="xxx",upstream_addr="10.244.19.254:8080",upstream_status="200",uri="/api/v1/cluster_metric/list_task_dimension",method="POST"} 96
apisix_http_status{code="200",route="3fb9d6c2",matched_uri="/api/v1/*",matched_host="xxx",service="",consumer="",node="10.244.19.254",host="xxx",upstream_addr="10.244.19.254:8080",upstream_status="200",uri="/api/v1/cluster_metric/list_task_dimension",method="POST"} 96
...
apisix_http_status{code="200",route="3fb9d6c2",matched_uri="/api/v1/*",matched_host="xxx",service="",consumer="",node="10.244.19.254",host="xxx",upstream_addr="10.244.19.254:8080",upstream_status="200",uri="/api/v1/file/upload",method="POST"} 3188
apisix_http_status{code="200",route="3fb9d6c2",matched_uri="/api/v1/*",matched_host="xxx",service="",consumer="",node="10.244.19.254",host="xxx",upstream_addr="10.244.19.254:8080",upstream_status="200",uri="/api/v1/file/upload",method="POST"} 3188

so we will see lots of error logs from prometheus:

ts=2025-01-22T08:51:08.867Z caller=scrape.go:1793 level=debug component="scrape manager" scrape_pool=serviceMonitor/apisix/apisix/0 target=http://10.244.5.32:9091/apisix/prometheus/metrics msg="Duplicate sample for timestamp" series="apisix_http_latency_bucket{type=\"apisix\",route=\"3fb9d6c2\",service=\"\",consumer=\"\",node=\"10.244.10.60\",host=\"xxx\",upstream_addr=\"10.244.10.60:8080\",upstream_status=\"200\",uri=\"/api/v1/user/routes/ws-f4d69b29-e0a5-44e6-bd92-acf4de9990f0\",method=\"GET\",le=\"100\"}"

this metrics is too large, we run 6 pod instance of apisix, i just curl one apisix metrics url, i got about 100mb results.

Expected Behavior

No response

Error Logs

all error logs is about the shdict:

2025/01/22 15:07:27 [error] 534#534: *2088505577 [lua] prometheus_resty_counter.lua:39: increasing counter in shdict: lru eviction: key=http_latency_bucket{type="request",route="3fb9d6c2",service="",consumer="",node="10.244.11.36",host="xxx",upstream_addr="10.244.11.36:8080",upstream_status="200",uri="/api/v1/notebook/7eb9852a-be8d-4fac-a593-31f5f7d864b0",method="GET",le="30000.0"}, context: ngx.timer
...
2025/01/22 16:53:00 [error] 499#499: *2098016584 [lua] prometheus.lua:973: log_error(): Shared dictionary used for prometheus metrics is full. REPORTED METRIC DATA MIGHT BE INCOMPLETE. Please increase the size of the dictionary or decrease metric cardinality.; key index: add key: idx=__ngx_prom__key_115158, key=http_latency_bucket{type="request",route="3fb9d6c2",service="",consumer="",node="10.244.11.36",host="xxx",upstream_addr="10.244.11.36:8080",upstream_status="200",uri="/api/v1/project/project-cc83c686-1515-454e-870b-202a20a67727",method="GET",le="Inf"} while logging request, client: 10.245.13.201, server: _, request: "GET /api/v1/project/project-cc83c686-1515-454e-870b-202a20a67727 HTTP/2.0", upstream: "http://10.244.11.36:8080/api/v1/project/project-cc83c686-1515-454e-870b-202a20a67727", host: "qz.sii.edu.cn", referrer: "https://xxx/jobs/distributedTraining?spaceId=ws-f4d69b29-e0a5-44e6-bd92-acf4de9990f0"

We accept the issue of insufficient shared dict memory, just hope to know why apisix report duplicate metrics.

Steps to Reproduce

no ideas

apisix config:

    nginx_config:    # config for render the template to genarate nginx.conf
        lua_shared_dict:                  
          prometheus-metrics: 200m            # yes, it's 200m
...
    plugin_attr:
      opentelemetry:
        set_ngx_var: true
      prometheus:
        expire: 16
        export_addr:
          ip: 0.0.0.0
          port: 9091
        export_uri: /apisix/prometheus/metrics
        metric_prefix: apisix_
        metrics:
          bandwidth:
            extra_labels:
            - host: $host
            - upstream_addr: $upstream_addr
            - upstream_status: $upstream_status
            - uri: $uri
            - method: $request_method
          http_latency:
            extra_labels:
            - host: $host
            - upstream_addr: $upstream_addr
            - upstream_status: $upstream_status
            - uri: $uri
            - method: $request_method
          http_status:
            extra_labels:
            - host: $host
            - upstream_addr: $upstream_addr
            - upstream_status: $upstream_status
            - uri: $uri
            - method: $request_method
        prefer_name: true

Environment

• APISIX version (run apisix version): 3.7.0 (helm version: 2.5.0)
• Operating system (run uname -a): Linux cpu-001 5.4.0-192-generic #212-Ubuntu SMP Fri Jul 5 09:47:39 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux
• OpenResty / Nginx version (run openresty -V or nginx -V): openresty/1.21.4.2
• k8s version:

$ kubectl version
Client Version: version.Info{Major:"1", Minor:"27", GitVersion:"v1.27.16", GitCommit:"cbb86e0d7f4a049666fac0551e8b02ef3d6c3d9a", GitTreeState:"clean", BuildDate:"2024-07-17T01:53:56Z", GoVersion:"go1.22.5", Compiler:"gc", Platform:"linux/amd64"}
Kustomize Version: v5.0.1
Server Version: version.Info{Major:"1", Minor:"27", GitVersion:"v1.27.16", GitCommit:"cbb86e0d7f4a049666fac0551e8b02ef3d6c3d9a", GitTreeState:"clean", BuildDate:"2024-07-17T01:44:26Z", GoVersion:"go1.22.5", Compiler:"gc", Platform:"linux/amd64"}

[yurkovoznyak]

I believe the issue is with metric expiration logic.

I was able to reproduce it locally when I set the expiration time to a low value (like expire: 10) and had more than 1 worker process (I tested on 6, but with more workers, it's easier to reproduce).

Removing metrics expiration configuration resolves duplicates

Environment

APISIX version (run apisix version): 3.11.0
Operating system (run uname -a): Linux 82435988518b 6.10.14-linuxkit #1 SMP Fri Nov 29 17:22:03 UTC 2024 aarch64 aarch64 aarch64 GNU/Linux
OpenResty / Nginx version (run openresty -V or nginx -V): openresty/1.25.3.2