Scaling Apache Pulsar for Multi-Tenant SaaS

Apache Pulsar’s multi-tenancy model is a standout feature—but scaling it in a SaaS environment presents real-world challenges. In this post, we’ll share lessons learned from designing and operating multi-tenant Pulsar architectures.

Namespace and tenant design

This ensures clean quota enforcement and RBAC scoping. Use Pulsar’s namespace and tenant hierarchy to logically separate workloads:

• One tenant per customer or environment
• Multiple namespaces for staging, dev, and prod
• Avoid namespace sprawl; document usage early
  
  

Enforce quotas and limits

Set limits on message rates, topic counts, and storage for each tenant.  This will prevent noisy neighbors and runaway workloads.  Be sure to monitor quota usage and alert before limits are hit.

bin/pulsar-admin namespaces set-retention my-tenant/ns –size 2G –time 6h

Monitor topic explosions

Multi-tenant environments often experience unexpected topic proliferation.  Make sure to enforce naming conventions and set topic auto-delete and TTL policies.  This will reduce broker memory use and metadata overhead.

Tune BookKeeper for write scalability

Pulsar relies on Apache BookKeeper for message durability. Be sure to scale Bookie nodes and tune journal syncs.  Use SSDs for write-ahead logs, and monitor write latency and ensemble size to prevent ingestion bottlenecks during tenant spikes.

Design for operational isolation

Use label-based metrics (e.g., tenant, namespace) in Prometheus and dashboards.  Add tenant ID to logs and alerts and set up per-tenant dashboards for usage visibility.  These settings will speed up troubleshooting and support SLA boundaries.

Summing it up

Pulsar offers a strong foundation for multi-tenant SaaS, but it requires thoughtful design to avoid noisy neighbors, metadata overload, and unexpected growth. From namespace strategy to BookKeeper tuning, small architecture decisions have big consequences at scale.

Need help designing a multi-tenant Pulsar platform? Reach out to talk architecture with our experts.