小编Cur*_*Guy的帖子

我在 OpenJDK11 中使用HotSpot的ExecutionSample 事件。

它有一个线程状态字段，但我只看到该字段的一个值： STATE_RUNNABLE

HotSpot 如何选择要采样的线程？为什么它们总是可运行的？

Kotlin 中的简单复现代码：

import jdk.jfr.Recording
import jdk.jfr.consumer.RecordingFile
import java.nio.file.Path

object ExecutionSampleTest {

    private const val EXECUTION_SAMPLE = "jdk.ExecutionSample"
    private val RECORDING_PATH = Path.of("/tmp/recording.jfr")

    @JvmStatic
    fun main(args: Array<String>) {
        Recording().use { recording ->
            recording.enable(EXECUTION_SAMPLE)
            recording.settings = recording.settings.plus("$EXECUTION_SAMPLE#period" to "1 ms")

            recording.start()
            repeat(100) {
                // start some sleeping threads, just so we've got something to sample
                Thread { Thread.sleep(20_000) }.start()
            }
            Thread.sleep(20_000)
            recording.stop()
            recording.dump(RECORDING_PATH)

            RecordingFile.readAllEvents(RECORDING_PATH).forEach {
                println("Thread state: ${it.getString("state")}")
            }
        }
    }
} …