.NullPointerException: Cannot invoke "java.io.InputStream.available()" because "this.val$is" is null

Hi there, I’ve got the the following error using the following example in https://github.com/fabric8io/kubernetes-client/blob/master/kubernetes-examples/src/main/java/io/fabric8/kubernetes/examples/kubectl/equivalents/PodExecEquivalent.java

2021-11-10 14:50:13,115 ERROR [io.fab.kub.cli.uti.InputStreamPumper] (pool-16-thread-1) Error while pumping stream.: java.lang.NullPointerException: Cannot invoke "java.io.InputStream.available()" because "this.val$is" is null
	at io.fabric8.kubernetes.client.utils.InputStreamPumper$1.read(InputStreamPumper.java:53)
	at io.fabric8.kubernetes.client.utils.InputStreamPumper.transferTo(InputStreamPumper.java:76)
	at io.fabric8.kubernetes.client.utils.InputStreamPumper.lambda$pump$0(InputStreamPumper.java:89)
	at java.base/java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1804)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:833)

Here is my code:

class Foo{
    val execLatch = CountDownLatch(1);
    private val LOG: Logger = LoggerFactory.getLogger(Foo::class.java)

    fun doSomething(): Unit {
        val out = ByteArrayOutputStream()
        val error = ByteArrayOutputStream()

        val execWatch = kubernetesClient.pods()
            .inNamespace(kubernetesClient.namespace)
            .withName("MY-POD")
            .inContainer("MY-CONTAINER")
            .writingOutput(out)
            .writingError(error)
            .usingListener(MyPodExecListener())
            .exec("du", "-s", "/home/abcd")

        val latchTerminationStatus: Boolean = execLatch.await(5, TimeUnit.SECONDS)
        if (!latchTerminationStatus) {
            LOG.warn("Latch could not terminate within specified time")
        }
        LOG.info("Exec Output: {} ", out)
        execWatch.close()
    }

    inner class MyPodExecListener : ExecListener {

        override fun onOpen(response: okhttp3.Response?) {
            println(response)
            LOG.info("Shell was opened")
        }

        override fun onFailure(t: Throwable?, response: okhttp3.Response?) {
            LOG.info("Some error encountered")
            execLatch.countDown()
        }

        override fun onClose(i: Int, s: String) {
            LOG.info("Shell Closing")
            execLatch.countDown()
        }
    }
}

[shawkins]

Should be a duplicate of #3384

[shawkins]

Perhaps something related to this topic, If I call the endpoint/method. At first run it shows the output in afterwards it doesnt:

It’s not related to the NPE. I’m not sure if there is a trace level for websocket traffic, if you can’t seem to get a log can you put breakpoints in ExecWebSocketListener.onMessage and cleanUpOnce to see if you are getting a message prior to the websocket being closed?