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1.25.1 • Public • Published

OpenTelemetry async_hooks-based Context Managers

NPM Published Version Apache License

This package provides two ContextManager implementations built on APIs from Node.js's async_hooks module. If you're looking for a ContextManager to use in browser environments, consider opentelemetry-context-zone or opentelemetry-context-zone-peer-dep.

The definition of the ContextManager interface and the problem it solves can be found here.


Two ContextManager implementations are exported:

The former should be preferred over the latter as its implementation is substantially simpler than the latter's, and according to Node.js docs,

While you can create your own implementation [of AsyncLocalStorage] on top of [AsyncHook], AsyncLocalStorage should be preferred as it is a performant and memory safe implementation that involves significant optimizations that are non-obvious to implement.

AsyncLocalStorage is available in node ^12.17.0 || >= 13.10.0, however AsyncLocalStorageContextManager is not enabled by default for node <14.8.0 because of some important bugfixes which were introduced in v14.8.0 (e.g., nodejs/node#34573).


It's possible that this package won't track context perfectly when used with certain packages. In particular, it inherits any bugs present in async_hooks. See here for known issues.

async_hooks is still seeing significant correctness and performance fixes, it's recommended to run the latest Node.js LTS release to benefit from said fixes.

Prior art

Context propagation is a big subject when talking about tracing in Node.js. If you want more information about it here are some resources:

Useful links


Apache 2.0 - See LICENSE for more information.

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