Node.js release notes

Thursday, January 18, 2018 - 10:28 Download


  • Added regression test for promise instrumentation and stack overflows.

Bug fixes

  • Fixed naming bug in Restify instrumentation regarding parameters to next.

    The instrumentation previously considered any truthy value passed to next to be an error. It is possible to pass a string or boolean to next in Restify to control further routing of the request. This would cause the middleware's mounting path to be erroneously appended to the transaction name.

  • Fixed access to bluebird.coroutine.addYieldHandler.

    This was accidentally not copied by our instrumentation making access to the function fail. This has been resolved and tests expanded to ensure no other properties were missed.

Wednesday, January 10, 2018 - 11:27 Download

New features

  • Added transaction_tracer.hide_internals configuration.

    This configuration controls the enumerability of the internal properties of the agent. Making these properties non-enumerable can have an impact on the performance of the agent. Disabling this option may decrease agent overhead.


  • Refactored promise instrumentation.

    This new instrumentation is far more performant than the previous and maintains a more sensible trace structure under a wider range of sequences.

  • Added concurrent environment scanning, limited to 2 reads at a time.

    This improves the performance of dependency scanning at agent startup, allowing the agent to connect to our services more quickly.

  • Refactored instrumentation tests to run against wide range of module versions.

    Instrumentation tests will be run against all supported major versions of every instrumented module. For releases, we will test against every supported minor version of the modules. This vastly improves our test coverage and should reduce the instances of regressions for specific versions of modules.

  • Added tests for all of bluebird's promise methods.

    These tests ensure that we 100% instrument bluebird. Some gaps in instrumentation were found and fixed. Anyone using bluebird should upgrade.

Bug fixes

  • Fixed a crashing error in the hapi instrumentation.

    When recording the execution of an extension listening to a server event (for example, 'onPreStart') the agent would crash due to the lack of a raw property on the first argument passed to the extension handler. The agent now checks the event before wrapping the extension handler and checks for the existence of the raw property before attempting to dereference off of it.

  • Fixed an incompatibility with the npm module mimic-response.

    The agent's HTTP instrumentation previously did not play well with the way mimic-response copied properties from an http.IncomingMessage. This caused modules that relied on that process, such as got, to hang.

  • Fixed naming rule testing tool to use same url scrubbing as the agent itself.

Wednesday, January 3, 2018 - 11:08 Download

New features

  • Added hapi v17 instrumentation

    Hapi v17 added support for promise-based middleware which broke transaction tracking in the agent. This caused issues in naming, as the agent will name the transaction after the path to the middleware that responded to a request.

  • Added instrumentation for vision@5

    Due to the way vision is mounted to the hapi server when using hapi v17.x, the agent's instrumentation would not pick up on the middleware being mounted. This new instrumentation now correctly times rendering done in the vision middleware.

  • Added unwrapOnce method to shim object

    This new method can be used to unwrap a single layer of instrumentation. unwrapOnce is useful in cases where multiple instrumentations wrap the same method and unwrapping of the top level is required.

  • Added isErrorWare checks around nameState.appendPath/nameState.popPath calls to avoid doubling up paths in transaction names

    Previously, the agent would append its transaction name with the path fragment where an error handler middleware was mounted. The extraneous path fragment will now be omitted, and the transaction will be named properly after the middleware that threw the error.

  • Added support for pg 6 on Node 5 or higher


  • Added parent property to webframework-shim segment description

  • Refactored existing hapi instrumentation for different server.ext() invocations

  • Refactored webframework-shim _recordMiddleware to construct different segment descriptions for callback- or promise-based middleware

  • Updated node-postgres@^6 versioned tests to avoid deprecation warning on direct module connect and end calls

  • Fixed running domain tests on Node 9.3.0.

  • Improved logging for CAT headers and transaction name-state management.

  • All json-safe-stringify calls now wrapped in try/catch

  • Removed lib/util/safe-json

Bug fixes

  • Fixed creating supportability metric when mysql2 goes uninstrumented.

  • Added a segmentStack.popto the middleware after in cases when an error is caught and there is no next handler

  • Fixed determining parents for middleware segments when transaction state is lost and reinstated

  • Added check to _recordMiddleware to avoid prepending a slash if original route is an array

  • Changed logic in http instrumentation to attach response.status to the transaction as a string

  • Updated startWebTransaction and startBackgroundTransaction to add nested transactions as segments to parent transactions

Tuesday, December 12, 2017 - 10:28 Download


  • Added Peter Svetlichny to the contributors list!


  • Optimized NameState#getPath.

  • Optimized shim.record.

  • Optimized shim.recordMiddleware.

  • Upgraded eslint to v4.

Bug fixes

  • Fixed parsing SQL for queries containing newlines.
Tuesday, November 28, 2017 - 12:28 Download


  • 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.
Wednesday, November 15, 2017 - 10:21 Download

New features

  • Instrumentation will now only modify the arity of wrapped functions when needed.

    This can be controlled with the matchArity property on a WrapSpec. Disabling arity matching has a significant, positive impact on the performance of instrumentation.


  • Added benchmarks for shimmer methods.

  • Pinned hapi tests at v16 due to incompatibility in hapi v17 with Node.js versions <8.

  • The agent's parsed queries will now only hold onto the stack that the query was made at, instead of an error object instance.

    Previously, the parsed query objects would hold onto an error instance, which would in turn hold onto references to all the functions in the stack when the error was created. This could cause memory issues if the functions were holding onto references to other pieces of data.

Bug fixes

  • Revert wrapping of https for Node ^8.9.1.

    The original cause for this problem was reverted by Node.

Thursday, November 2, 2017 - 10:20 Download


  • Added Node 9 to test suite.

  • Removed problematic tests for ancient version of Hapi (7.1).

  • Document purpose of throw in tracer to prevent developer confusion.

  • Added script for running agent micro benchmarks.

  • Added benchmarks for all the Shim and Tracer methods.

Bug fixes

  • Fixed a bug with Node >=8.9 that prevented https externals from being recorded.
Tuesday, October 24, 2017 - 10:20 Download


  • Agent will attempt to reconnect to the collector forever after backing off to 5 minute delays.

Bug fixes

  • Refactored environment scan to improve startup time and fix cyclical symlink resolving.
Monday, October 16, 2017 - 12:56 Download

New features


  • Added benchmark for performance of function wrapping.

  • Added Garbage Collection information to async_hooks benchmark.

  • Improved trace-level logging for capturing queries.

  • Added cases for omitting the agent with and without async hooks to the async hooks microbenchmark.

Bug fixes

  • Pinned version of Mocha to 3.x due to the incompatibility of Mocha v4 and Node v0.10 and v0.12.
Tuesday, September 26, 2017 - 14:45 Download

Bug fixes

  • Hapi handlers will now preserve the defaults associated with them.

    Previously when wrapping handlers, the agent would drop the associated defaults on the ground, these are now properly forwarded to the wrapper. Big thanks to Sean Parmelee (@seanparmelee) for finding the root cause of this bug and reporting it!

  • Fixed starting the agent with an invalid process version.

  • Pinned request version for testing old versions of Node.

  • Added tests for feature flags created at agent initialization.