Crash: java.lang.RuntimeException: MulticastLock under-locked react-native-udp

[hubciorz]

Description

App sometimes crashes after going to background (Android)

Error

com.tradle.react.UdpSockets$6.doInBackgroundGuarded
java.lang.RuntimeException: MulticastLock under-locked react-native-udp

Stack traces

android.net.wifi.WifiManager$MulticastLock.release WifiManager.java:4268
com.tradle.react.UdpSockets$6.doInBackgroundGuarded UdpSockets.java:273
com.tradle.react.UdpSockets$6.doInBackgroundGuarded UdpSockets.java:263
com.facebook.react.bridge.GuardedAsyncTask.doInBackground GuardedAsyncTask.java:36
com.facebook.react.bridge.GuardedAsyncTask.doInBackground GuardedAsyncTask.java:20
android.os.AsyncTask$3.call AsyncTask.java:378
java.util.concurrent.FutureTask.run FutureTask.java:266
java.util.concurrent.ThreadPoolExecutor.runWorker ThreadPoolExecutor.java:1167
java.util.concurrent.ThreadPoolExecutor$Worker.run ThreadPoolExecutor.java:641
java.lang.Thread.run Thread.java:919

Steps to reproduce

Hard to say. It happens very rarely and it seems that you need to go to background at the right moment.

Expected behavior

No crash, perhaps.

Relevant information

react-native	0.62.1
react-native-udp	4.0.3 (but happens on earlier versions, too)

Occurred on

Device	OS
Xperia XZ2	Android 10.0
LG K4	Android 6.0.1

[Rapsssito]

@hubciorz, thanks for your feedback! I don't know what is causing the error, but I am working on switching all multi-thread code to the Java standard API. It might fix your issue. I will create a PR which will close this issue when merged so you are notified.

[hubciorz]

@Rapsssito Good to hear that! Good luck and thank you.

[github-actions]

🎉 This issue has been resolved in version 4.0.4 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

Your semantic-release bot 📦🚀

[hubciorz]

@Rapsssito So far so good. No crashes. Tested by about 1000 users. I will let you know if there is any. Many thanks!

[hubciorz]

@Rapsssito It seems that crashes happen less frequently, but if they do, stack trace is quite different:

com.tradle.react.UdpSockets$6.run
java.lang.RuntimeException: MulticastLock under-locked react-native-udp

android.net.wifi.WifiManager$MulticastLock.release WifiManager.java:4291
com.tradle.react.UdpSockets$6.run UdpSockets.java:257
java.lang.Thread.run Thread.java:919
java.util.concurrent.ThreadPoolExecutor.runWorker ThreadPoolExecutor.java:1167
java.util.concurrent.ThreadPoolExecutor$Worker.run ThreadPoolExecutor.java:641
java.lang.Thread.run Thread.java:919

[Rapsssito]

@hubciorz could you provide me with an example code so I can reproduce the issue?

[hubciorz]

@Rapsssito This is just a standard udp listening code, as I pasted in #143 (btw, this one has been fixed). It's hard to reproduce the bug. A hint - going to background/foreground may be the key.

this.udpSocket = createSocket({ type: "udp4", reuseAddr: true })
  this.udpSocket.on("message", this.onUdp.bind(this))
  this.udpSocket.on("error", this.onUDPError.bind(this))
  this.udpSocket.on("listening", this.onUDPListening.bind(this))
  this.udpSocket.bind(7979)

  private onUDPListening(err) {
    if (err) {
      log.error("Error when listening on UDP discovering socket:", err)
      return
    }

    if (this.udpSocket) {
      log.debug("Setting multicast for socket:", this.udpSocket)
      this.udpSocket.setBroadcast(true)
      this.udpSocket.addMembership(MULTICAST_GROUP)
    } else {
      log.debug("Error when setting multicast for socket. Socket is null")
    }
  }

  private onUDPError(err) {
    log.error("Error on UDP discovering socket:", err)
  }

...
// AppState change detection logic

[hubciorz]

@Rapsssito I think it is likely to happen when someone loses wifi connection for a while. Please take a look a these comments:
andriydruk/RxDNSSD#59 (comment)
andriydruk/RxDNSSD#59 (comment)

[Rapsssito]

@hubciorz thanks! However, I will take care of #147 first since crashes happen more frequently. I will come back to this one once that issue is fixed.

[Rapsssito]

Fixed by #148