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Monitoring and Metrics

How to track and debug bundler performance in ERC-4337 systems.

Running a reliable bundler requires robust observability. From mempool activity to simulation results and gas refunds, operators need insight into every layer of the ERC-4337 stack.

📊 What to Monitor

UserOp Lifecycle

  • Ingress: Count of UserOps received per second
  • Validation results: pass/fail reasons
  • Bundle size and frequency
  • Inclusion latency (time-to-handleOps)

Simulation

  • Calls to simulateValidation
  • Revert rates by failure class (signature, paymaster, initCode)
  • Gas estimation accuracy

EntryPoint Interaction

  • Successful vs failed handleOps() calls
  • Average gas used per UserOp
  • Revenue tracking: priority fee, refund breakdown

🔄 Integration with Alerting

  • Alert on sudden spikes in rejected UserOps
  • Monitor bundler uptime (especially if self-hosted)
  • Track deviation between simulated and actual gas usage

✅ Summary

A performant and trustworthy bundler is a transparent one. Whether you're running infrastructure at scale or testing locally, observability is essential to understanding mempool dynamics, simulation accuracy, and end-to-end UserOp throughput.