Node.js agent v2.4.1

Improvements

• Added promise benchmarks to test non-async_hooks instrumentation.
• Added logging for external calls made outside of a transaction.
• Added logging for when unhandledRejection is noticed.
• Improved performance of creating and merging metrics.
• Improved performance of tracer.bindFunction.
• Removed try-catch around internal property setting on older versions of Node.

Bug fixes

• Moved require calls for vendor metadata to module-level.