Distributed Systems

HAProxy StatefulSet update fails during high concurrency load testing

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Problem Description During high‑concurrency load testing of an AI inference benchmark, a StatefulSet that runs HAProxy as a front‑end load balancer fails to roll forward. The rolling update aborts with messages such as: RollingUpdateStatefulSetStrategy aborted: waiting for pod to become Ready timed out Readiness probe failed: Get http://127.0.0.1:8080/health: dial tcp 127.0.0.1:8080: connect: connection refused [ERROR] … Read more

Ingress routing misconfiguration in Docker GPU cluster

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Problem Description In a Docker Swarm GPU cluster (A100/H100), services that request –gpus become unreachable through the Swarm ingress routing mesh. Clients receive HTTP 502/504 errors, and the Docker daemon logs report failures such as: Failed to create endpoint: network ingress: driver failed programming the network: MTU mismatch Ingress routing mesh: connection timed out (504) … Read more

Nginx proxy pass fails after Kubernetes deployment

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Problem Description After a rolling update of a Deployment in a Kubernetes cluster, the NGINX Ingress controller started returning 502 Bad Gateway and 504 Gateway Timeout for the affected host. The HTTP response body was empty, and the NGINX error log contained entries such as: 2024/07/31 12:45:12 [error] 12#12: *12345 connect() failed (111: Connection refused) … Read more

RAG embedding model dimension mismatch after deployment update

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Problem Description The RAG (Retrieval‑Augmented Generation) service deployed on a Kubernetes cluster began returning vector dimension mismatch errors after a routine rolling update. The symptoms observed across multiple pods were: FAISS index load failures: ValueError: Expected embedding dimension 768 but got 1024 Cosine‑similarity runtime errors: RuntimeError: shape mismatch for dot product: (batch, 768) vs (batch, … Read more

HAProxy timeouts during batch ingestion to multi-GPU training cluster

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Problem: HAProxy Timeouts During High‑Throughput Batch Ingestion In a multi‑GPU training cluster, HAProxy fronts a set of tensorflow/torchserve workers that accept large JSON or binary payloads via HTTP POST. During nightly batch uploads (10 GB + per request) clients observe: HTTP 504 “Gateway Timeout” with HAProxy log entry SC (client timeout) Intermittent HTTP 502 “Bad Gateway” with log entry sH … Read more

Nginx invalid sampling parameter error during high traffic

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Problem Description During a traffic surge on a high‑volume API gateway powered by Nginx Plus, the following symptoms were observed: Intermittent 502 Bad Gateway responses. HTTP 500 payloads containing the phrase invalid sampling parameter. NGINX error log entries such as: 2024/01/15 10:23:41 [error] 1123#1123: *4567 configuration file /etc/nginx/conf.d/api.conf test failed: invalid sampling_rate 1.5, allowed range is … Read more

Kubernetes pod OOMKilled after increasing AI model size

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Problem – Pods OOMKilled After Increasing AI Model Size An AI inference service deployed on a multi‑node Kubernetes cluster started failing shortly after the model binary grew from 2 GB to 4 GB. The symptoms observed across the cluster were: State: Terminated Reason: OOMKilled in kubectl describe pod output. Node‑level memory pressure events and occasional pod eviction … Read more

RAG retrieval empty results behind HAProxy in CI/CD pipeline

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Problem – RAG retrieval returns empty results behind HAProxy in CI/CD pipelines During automated end‑to‑end tests a Retrieval‑Augmented Generation (RAG) service intermittently returns no documents. The symptom is observed only when the request traverses an HAProxy instance that load‑balances traffic across several identical backend replicas. Typical error messages: HAProxy log entry: <…> 0/0/0/30/30 504 0 … Read more

Docker container DNS resolution fails intermittently in multi-region Kubernetes

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Problem – Intermittent DNS Resolution Failures in Docker Containers Across Multi‑Region Kubernetes AI inference services deployed as Docker containers on Amazon EKS clusters in several AWS regions (e.g., us-east-1, eu-central-1, ap-south-1) experience sporadic failures when resolving external endpoints such as model registries, third‑party APIs, or telemetry services. The failures manifest as: Go errors: dial tcp: … Read more

HAProxy multimodal alignment error in Kubernetes cluster

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Problem: HAProxy “multimodal alignment” errors in a mixed‑protocol Kubernetes ingress In a GKE‑based AI platform the same HAProxy ingress is used to expose: TensorFlow Serving (gRPC over HTTP/2) FastAPI inference endpoints (HTTP/1.1) WebSocket streams (HTTP/1.1 upgrade) After a rolling update the following symptoms appeared: [WARNING] 2026/07/08 10:12:45 HA-Proxy[WARN] : content mismatch, header size exceeds payload … Read more