Automatically tracked dependencies are tracked _twice_ from time to time

👋,

We’re building a product which acts as a reverse proxy and relays incoming requests to remote backends. Everything is instrumented through ApplicationInsights SDK for Nodejs (https://github.com/microsoft/ApplicationInsights-node.js).

We’ve just discovered a weird behavior. While analyzing the telemetry stored in ApplicationInsights, for a very small percentage (0.07%) of the traffic, it looks like the calls to the backends are tracked twice.

When that happens, the vast majority of this duplicate tracks shows one successful dependency call, and one failed dependency call. However, one can also find entries with two successful dependency calls or two failed ones.

Those duplicate entries bear the same dependency.timestamp, dependency.id, … but usually their duration differs by few milliseconds.

Although the numbers seem low, this is quite annoying from a monitoring standpoint (false positives, …).

Unfortunately, we haven’t been unable to create a small scale repro case.

How can we proceed further? Would it be possible to set up a screen sharing session so that we could demonstrate the finding?

In order to help move the ball further, below are three “proofs” of those behaviors, extracted from our ApplicationInsights instance. Some of the data has been redacted, it should help share what we actually encounter.

2.failed.dependencies.txt 2.successful.dependencies.txt 1.fail.and.1.successful.dependencies.txt

/cc @hectorhdzg

[nulltoken]

@hectorhdzg Just confirmed that the change fixed our duplicate issue as well.

Tons of thanks !

❤️

[nulltoken]

@hectorhdzg Sorry for the delay. I’ve completely missed your message from March, 15th. I’ll come back to you in the following days with some answers.