IssueTracker

androidx.metrics module used: 1.0.0-beta01

androidx.metrics version used: 1.0.0-beta01

Devices/Android versions reproduced on: Various

The example JankStatsAggregator class can produce ConcurrentModificationException for listeners that perform some additional operations on it. Presumably because of how FrameData objects are internally mutated.

It appears that JankStatsAggregator.issueJankReport attempts to account for that with copies, but it was suggested that there's something internal to the library causing this.

For example:

private val reportListener = JankStatsAggregator.OnJankReportListener { _, _, jankFrameData -> 
    jankFrameData.filter(...).map { frame ->
        // Do something with FrameData and/or StateInfo
    }
}

This usage results in rare concurrency exceptions.