Okhttp: RealWebSocket send throws writerTask NPE

[Naitbit]

okhttp 4.3.0 throws NPE each time I try to send command via websocket.
writerTask is null in RealWebSocket::runWriter

  private fun runWriter() {
    this.assertThreadHoldsLock()

    taskQueue.schedule(writerTask!!) // crashes in this line
  }

Stacktrace:

Caused by kotlin.KotlinNullPointerException
       at okhttp3.internal.ws.RealWebSocket.runWriter + 398(RealWebSocket.java:398)
       at okhttp3.internal.ws.RealWebSocket.send + 352(RealWebSocket.java:352)
       at okhttp3.internal.ws.RealWebSocket.send + 332(RealWebSocket.java:332)

test:

import okhttp3.OkHttpClient
import okhttp3.Request
import okhttp3.WebSocketListener
import okhttp3.mockwebserver.MockWebServer
import org.junit.Rule
import org.junit.Test


class OkHttpBug {
    @get:Rule
    val server = MockWebServer()

    @Test
    fun test() {
        val request = Request.Builder()
            .url(server.url("/path"))
            .header("User-Agent", "Test Case")
            .build()
        val client = OkHttpClient()
        val listener = object : WebSocketListener() {

        }
        val command = """{ "id": "file" }"""
        val webSocket = client.newWebSocket(request, listener)
        webSocket.send(command)
        webSocket.close(1000, "RealWebSocket crashes with runWriter writerTask!! NPE")
    }
}

This seems to be 100% reproducible in 4.3.0. Had about 1000 crashes on that version on small amount of sessions.
This (almost) does not happen with the same code on okhttp 4.2.2 (2 crashes in 1000x user count in much longer period)

[swankjesse]

Will fix.

[swankjesse]

Great bug report. Will try to get a release out tonight.
https://github.com/square/okhttp/pull/5707

[swankjesse]

FYI, OkHttp 4.3.1 is released.

[simtse]

Hmm @swankjesse we ran into a similar issue and we're using OkHttp 4.5.0.

kotlin.KotlinNullPointerException
        at okhttp3.internal.ws.RealWebSocket.writePingFrame$okhttp(RealWebSocket:569)
        at okhttp3.internal.ws.RealWebSocket$initReaderAndWriter$$inlined$synchronized$lambda$1.runOnce(TaskQueue.kt:219)
        at okhttp3.internal.concurrent.TaskRunner.runTask(TaskRunner.kt:116)
        at okhttp3.internal.concurrent.TaskRunner.access$runTask(TaskRunner.kt:42)
        at okhttp3.internal.concurrent.TaskRunner$runnable$1.run(TaskRunner.kt:65)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
        at java.lang.Thread.run(Thread.java:919)

nvm, i'm going to open up another issue for this.

[tomsammons]

Hey @simtse, are you still facing this issue and were you able to open an issue for it? It looks like I'm also facing the same issue on 4.5.0 and 4.6.0.