Test.kt

  @Test
  fun closeAJarFileWhileSomebodyIsReadingIt() {
    val someJarResource = this::class.java.classLoader.getResource("LICENSE-junit.txt")!!

    val connectionA = someJarResource.openConnection()
    val sourceA = connectionA.getInputStream().source().buffer()

    val connectionB = someJarResource.openConnection()
    val sourceB = connectionB.getInputStream().source().buffer()

    connectionA.useCaches = false
    assertThat(sourceA.readUtf8()).contains("JUnit")
    sourceA.close()

    assertThat(sourceB.readUtf8()).contains("JUnit")
    sourceB.close()
  }

This crashes on line 15:

Stream closed
java.io.IOException: Stream closed
	at java.base/java.util.zip.InflaterInputStream.ensureOpen(InflaterInputStream.java:68)
	at java.base/java.util.zip.InflaterInputStream.read(InflaterInputStream.java:143)
	at java.base/java.io.FilterInputStream.read(FilterInputStream.java:119)
	at okio.InputStreamSource.read(JvmOkio.kt:93)
	at okio.Buffer.writeAll(Buffer.kt:1309)
	at okio.RealBufferedSource.readUtf8(RealBufferedSource.kt:325)
	at closeAJarFileWhileSomebodyIsReadingIt(FileLeakTest.kt:172)

It doesn’t crash if you remove this line:

connectionA.useCaches = false

And it doesn’t crash if you don’t open sourceB until after closing sourceA.

Setting useCaches to false causes sourceA to close a .jar file that it doesn’t own.

awesome! explains the race condition