# gRPC
> 6 posts about gRPC, summarised, each linking to the original.

## Articles

### [How and Why Netflix Built a Real-Time Distributed Graph: Part 3 — Querying the graph with gRPC…](https://yomu.fyi/post/how-and-why-netflix-built-a-real-time-distributed-graph-part-3-queryin.md)
- Company: [Netflix](https://yomu.fyi/company/netflix.md)
- Author: Netflix Technology Blog
- Published: Aug 7, 2026

Netflix designed a query execution serving layer for its Real-Time Distributed Graph to power sub-100ms responses across diverse graph traversal workloads spanning billions of nodes and edges. To prevent compounding network delays in multi-hop queries, the engine uses a breadth-first traversal model that batches entity lookups across entire frontier levels rather than tracing paths depth-first. The entire serving architecture relies on asynchronous composition across small thread pools of 16 to 24 threads, ensuring no thread blocks while waiting on remote storage or enrichment I/O. Selective caching via EVCache targets stable properties with volatility-matched TTLs, producing 70 to 80 percent cache hit rates and reducing backend storage calls by three to four times. A layered filtering hierarchy pushes depth and edge limits directly to the storage tier, eliminating bespoke code changes while isolating system resources against excessive fan-out.


### [Grab's service mesh evolution: From Consul to Istio](https://yomu.fyi/post/grab-s-service-mesh-evolution-from-consul-to-istio.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Hilman Kurniawan
- Published: Jul 16, 2025

Grab operated over 1,000 microservices across hybrid infrastructure using Consul alongside a fallback mechanism called Catcher. Single-point-of-failure vulnerabilities in Consul servers and limited support for multi-cluster operations prompted an evaluation of alternative mesh technologies, ultimately leading to the selection of Istio. Grab avoided the standard single-control-plane-per-cluster pattern by deploying multiple external control planes in dedicated Kubernetes clusters arranged in active-active pairs. Migration began in Q4 2024, shifting traffic across AWS and GCP while handling both HTTP and gRPC protocols with gradual traffic-shifting and rollback mechanisms.


### [Message Center - Redesigning the messaging experience on the Grab superapp](https://yomu.fyi/post/message-center-redesigning-the-messaging-experience-on-the-grab-supera.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Jonathan Lee
- Published: Apr 17, 2023

Grab redesigned its messaging infrastructure from GrabChat to Message Center to overcome two-party chat limitations and support complex superapp requirements like group conversations and varied user roles. The architecture separates core processing logic from message delivery by splitting the system into a backend processor and an independently scalable postman service. Communication relies on an in-house TCP gateway named Hermes that proxies client payloads via gRPC, alongside Apache Kafka streams and Amazon SQS delay queues. Custom client-server acknowledgements and a DynamoDB event store ensure reliable message delivery even across dropped mobile TCP connections and offline reconnects.


### [Serving Driver-partners Data at Scale Using Mirror Cache](https://yomu.fyi/post/serving-driver-partners-data-at-scale-using-mirror-cache.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Indrajit Sarkar
- Published: Jan 26, 2021

Grab's Drivers Data service handles up to 10,000 requests per second during peak hours to supply driver information across backend microservices. The original setup used MySQL with Redis and standalone in-memory local caches, but yielded a low 25% local cache hit rate due to traffic patterns characterized by high burst frequency for individual drivers alongside redundant database calls across nodes. To solve this, the team developed Mirror Cache, an in-memory caching system that pairs Dgraph's Ristretto library with an asynchronous gRPC replication layer to mirror updates across cluster nodes. The replicator batches updates within the same AWS availability zone and forwards data to single nodes across zones to minimize transfer overhead. Production deployment increased the in-memory cache hit rate to approximately 75% and reduced direct MySQL queries by 5%.


### [Using Grab’s Trust Counter Service to Detect Fraud Successfully](https://yomu.fyi/post/using-grab-s-trust-counter-service-to-detect-fraud-successfully.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Chao Wang
- Published: Oct 21, 2019

Grab's Trust Platform team built the Counter service to detect fraud across business verticals like transportation, food, and payments. The platform replaces manual, multi-week engineering cycles with a self-service UI where data analysts can define and experiment with counters independently. Operating on an asynchronous ingestion and synchronous transaction model, the architecture evaluates incoming stream data, enriches it via internal services, and persists aggregated signals to ScyllaDB through Grab-Stats. A multi-bucket strategy partitions queries into fifteen-minute, hourly, and daily granularities to maintain low-latency query aggregations across wide time ranges under strict SLAs.


### [Mockers - Overcoming Testing Challenges at Grab](https://yomu.fyi/post/mockers-overcoming-testing-challenges-at-grab.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Mayank Gupta
- Published: Sep 18, 2018

Grab operates over 250 microservices communicating over HTTP and gRPC, making shared staging environments costly, ambiguous in ownership, and fragile due to inconsistent data and uncoordinated deployments. To address these testing bottlenecks, Grab created Mockers, a Go SDK and CLI tool backed by a central monorepo of mock servers for local-box and CI testing. Mockers automatically generates HTTP and gRPC mock servers from Swagger specifications and protobuf files, returning configured network responses without internal business logic. By incorporating Grab's in-house chaos SDK middleware, Mockers also enables repeatable resiliency and contract testing locally without relying on code-level mocks. While Grab still mandates integration testing on distributed staging environments with live data, Mockers enables developers to detect complex defects and contract mismatches earlier.