ANR Caused by deadlock

[res0nance]

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Describe the bug
There seems to be a deadlock in LaunchDarkly's SDK code

To reproduce
Unable to provide direct steps to reproduce this issue but a stacktrace is provided below

Expected behavior
LD should not cause ANRs

Logs

These two stack traces block each other.

com.launchdarkly.sdk.android.Throttler.attemptRun (Throttler.java:40)
com.launchdarkly.sdk.android.ConnectivityManager.startUp (ConnectivityManager.java:297)
com.launchdarkly.sdk.android.ConnectivityManager$3.onSuccess (ConnectivityManager.java:341)
com.launchdarkly.sdk.android.ConnectivityManager$3.onSuccess (ConnectivityManager.java:338)
com.launchdarkly.sdk.android.ConnectivityManager.voidSuccess (ConnectivityManager.java:273)
com.launchdarkly.sdk.android.ConnectivityManager.stopStreaming (ConnectivityManager.java:194)
com.launchdarkly.sdk.android.ConnectivityManager.reloadUser (ConnectivityManager.java:338)
com.launchdarkly.sdk.android.LDClient.identifyInternal (LDClient.java:313)
com.launchdarkly.sdk.android.LDClient.identifyInstances (LDClient.java:335)
com.launchdarkly.sdk.android.LDClient.identify (LDClient.java:301)

com.launchdarkly.sdk.android.ConnectivityManager.lambda$new$0 (ConnectivityManager.java:59)
com.launchdarkly.sdk.android.ConnectivityManager.$r8$lambda$nWWvGCieHvstn5YcNkEA7rFcAHs (ConnectivityManager.java)
com.launchdarkly.sdk.android.ConnectivityManager$$InternalSyntheticLambda$0$6761b2069fd0126b9b6e516b99ae60d1488c7998e41b5b3a6b9d3e61ee6bcf3b$0.run (ConnectivityManager.java)
com.launchdarkly.sdk.android.Throttler.run (Throttler.java:36)
com.launchdarkly.sdk.android.Throttler.$r8$lambda$0hIZ81XyILcbRmSVeAlWXsmjPCE (Throttler.java)
com.launchdarkly.sdk.android.Throttler$$InternalSyntheticLambda$1$47657271ca77a10c09f298b0fc296b8a4869f692acbfbf01e4d849ee7f0d0a78$2.run (Throttler.java)

SDK version
3.1.4

Language version, developer tools
TargetSDK = 31
MinSDK = 21
KotlinVersion 1.6.10

OS/platform
Android 12 also happens on Android 11 but given this issue it might be possible on any android version

[louis-launchdarkly]

Hello @res0nance, based on your stack track and the open ANR issue that we are investigating, given the variable is synchronized, we suspect that this has to do with the SDK's background updating behavior (in which the app is waiting for a response but the Android OS thinks the app is not doing anything and report an ANR). While we are gathering more information about this, can you please try to turn off the background updating behavior and see does the issue goes away?

android-client-sdk/launchdarkly-android-client-sdk/src/main/java/com/launchdarkly/sdk/android/LDConfig.java

Line 538 in ff3a0ab

public LDConfig.Builder disableBackgroundUpdating(boolean disableBackgroundUpdating) {

Please report back if the issue still persists after the change.

[res0nance]

Hey @louis-launchdarkly , we unfortunately do not wish to disable the background updating, I've done some analysis and opened a PR which hopefully you can check out.

[aengelberg]

Your fix for this is in the 3.1.6 release. Thank you!