catch harvest callback error

[joway]

CHANGE LOG

fix crush when Error: Callback was already called.

INTERNAL LINKS

NOTES

[joway]

When we enable newrelic proxy option, it seems sometimes will have ECONNRESET error, and the nodejs process will crush.

So we need to add try catch on callback function to prevent it.

[michaelgoin]

@joway thank you for the contribution! A try/catch may not be how we want to solve this long-term, as we need to track down why this is happening and prevent it, but this is a good starting point to try to narrow-in on the issue.

Would it be possible to create a test to reproduce the issue as you understand it? A module such as nock can be helpful to trigger such issues. We use it in a few places in our tests, which can be used for examples such as test/unit/agent/harvest.test.js. This would help determine if the solution is ideal and also prevent future regressions.

Thank you!

[michaelgoin]

Hi!

We pushed a patch in version 5.6.4 that prevents this issue from throwing errors and also attempts to capture where the multiple calls were originating from. Using a version of the agent ^5.6.4, if you see the new log message indicating the attempt at multiple callback invocations, please let us know as it will help us further track down the underlying issue.

I'll be closing this PR, since we won't be accepting the immediate changes, but we appreciate the help.

Thank you,

Michael

[joway]

Hi, @michaelgoin ! Thanks for your great work!