cadonna commented on a change in pull request #9273:
URL: https://github.com/apache/kafka/pull/9273#discussion_r501793433
##########
File path: streams/src/main/java/org/apache/kafka/streams/KafkaStreams.java
##########
@@ -364,6 +370,73 @@ public void setUncaughtExceptionHandler(final
Thread.UncaughtExceptionHandler eh
}
}
+ /**
+ * Set the handler invoked when a {@link
StreamsConfig#NUM_STREAM_THREADS_CONFIG internal thread}
+ * throws an unexpected exception.
+ * These might be exceptions indicating rare bugs in Kafka Streams, or they
+ * might be exceptions thrown by your code, for example a
NullPointerException thrown from your processor
+ * logic.
+ * <p>
+ * Note, this handler must be threadsafe, since it will be shared among
all threads, and invoked from any
+ * thread that encounters such an exception.
+ *
+ * @param streamsUncaughtExceptionHandler the uncaught exception handler
of type {@link StreamsUncaughtExceptionHandler} for all internal threads;
{@code null} deletes the current handler
+ * @throws IllegalStateException if this {@code KafkaStreams} instance is
not in state {@link State#CREATED CREATED}.
+ */
+ public void setUncaughtExceptionHandler(final
StreamsUncaughtExceptionHandler streamsUncaughtExceptionHandler) {
+ final StreamsUncaughtExceptionHandler handler = throwable ->
handleStreamsUncaughtException(throwable, streamsUncaughtExceptionHandler);
+ synchronized (stateLock) {
+ if (state == State.CREATED) {
+ for (final StreamThread thread : threads) {
+ if (streamsUncaughtExceptionHandler != null) {
Review comment:
I do not think we need to emulate the behavior of the java uncaught
exception handler here. I do not see why a user should try to reset the
uncaught exception handler. If we receive this requirement, we can still add
it. I have the impression the "reset" makes this code unnecessarily complex.
##########
File path: streams/src/test/java/org/apache/kafka/streams/KafkaStreamsTest.java
##########
@@ -617,7 +619,19 @@ public void
shouldThrowExceptionSettingUncaughtExceptionHandlerNotInCreateState(
final KafkaStreams streams = new
KafkaStreams(getBuilderWithSource().build(), props, supplier, time);
streams.start();
try {
- streams.setUncaughtExceptionHandler(null);
+
streams.setUncaughtExceptionHandler((Thread.UncaughtExceptionHandler) null);
+ fail("Should throw IllegalStateException");
+ } catch (final IllegalStateException e) {
+ // expected
+ }
+ }
Review comment:
Sorry, my bad! It doesn't matter whether it is called or not, since the
`IllegalStateException` is thrown.
##########
File path: streams/src/test/java/org/apache/kafka/streams/KafkaStreamsTest.java
##########
@@ -617,7 +619,19 @@ public void
shouldThrowExceptionSettingUncaughtExceptionHandlerNotInCreateState(
final KafkaStreams streams = new
KafkaStreams(getBuilderWithSource().build(), props, supplier, time);
streams.start();
try {
- streams.setUncaughtExceptionHandler(null);
+
streams.setUncaughtExceptionHandler((Thread.UncaughtExceptionHandler) null);
+ fail("Should throw IllegalStateException");
+ } catch (final IllegalStateException e) {
+ // expected
+ }
+ }
+
+ @Test
+ public void
shouldThrowExceptionSettingStreamsUncaughtExceptionHandlerNotInCreateState() {
Review comment:
Actually, there are two tests missing. With the test you added, you test
the `else` branch on line 400 in `KafkaStreams`. But you do not test the
`then` branch of the same `if` statement and within the `then` branch there are
again a `then` branch and a `else` branch to test.
If you do without the inner `else` branch as I proposed in another comment,
you need to test the exception that is thrown when `null` is passed to the
method.
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