MSIDLastRequestTelemetry perfTelemetry grows unbounded

[martinregnerlarsen]

In some circumstances perfTelemetry seems to grow unbounded ending up causing apps being shut down on iOS due to excessive memory usage.

We have a bunch of iPhones running an app written in React Native using MSAL for Objective-C to authenticate. The phones are running in shared device mode, which may be of importance.

What we see is that over a time span of a couple of weeks the most used phones starting to be sluggish, getting MemoryWarnings from iOS and ultimately getting shut down due to excessive memory usage. When that started it got worse and worse until memory usage crashes happened after few minutes of using the app.

Restart of the app didn't work, but a complete reset of the phone brought it back, where we had some weeks of good behavior until the crashing started again.

During investigation we could see that the perfTelemetry in MSIDLastRequestTelemetry seems to grow unbounded on these phones, in the case we looked at storing more than 80.000 records for silent token fetching.

These records are stored to disk and persisted over app restarts and seems to be also cloned (probably due to thread safety) multiple times, causing the app memory usage to spike over 2 GB.

I don't know why this happens. I couldn't actually find out when the perfTelemetry is supposed to be cleared, but I guess it doesn't always happen otherwise people would clearly notice.

Right now we workaround this by deleting the msal.telemetry.lastRequest file before initializing MSAL, as I coulnd't find any way to disable the telemetry collection.

[juan-arias]

Thank you for reporting this @martinregnerlarsen
We are working to fix this.