ableegoldman commented on a change in pull request #9487:
URL: https://github.com/apache/kafka/pull/9487#discussion_r525701691
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File path: streams/src/main/java/org/apache/kafka/streams/KafkaStreams.java
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@@ -366,6 +377,90 @@ public void setUncaughtExceptionHandler(final
Thread.UncaughtExceptionHandler eh
}
}
+ /**
+ * Set the handler invoked when an {@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.
+ * The handler will execute on the thread that produced the exception.
+ * In order to get the thread that threw the exception,
Thread.currentThread().
+ * <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
+ * @throws IllegalStateException if this {@code KafkaStreams} instance is
not in state {@link State#CREATED CREATED}.
+ * @throws NullPointerException if streamsUncaughtExceptionHandler is null.
+ */
+ public void setUncaughtExceptionHandler(final
StreamsUncaughtExceptionHandler streamsUncaughtExceptionHandler) {
+ final Consumer<Throwable> handler = exception ->
handleStreamsUncaughtException(exception, streamsUncaughtExceptionHandler);
+ synchronized (stateLock) {
+ if (state == State.CREATED) {
+ Objects.requireNonNull(streamsUncaughtExceptionHandler);
+ for (final StreamThread thread : threads) {
+ thread.setStreamsUncaughtExceptionHandler(handler);
+ }
+ if (globalStreamThread != null) {
+ globalStreamThread.setUncaughtExceptionHandler(handler);
+ }
+ } else {
+ throw new IllegalStateException("Can only set
UncaughtExceptionHandler in CREATED state. " +
+ "Current state is: " + state);
+ }
+ }
+ }
+
+ private void defaultStreamsUncaughtExceptionHandler(final Throwable
throwable) {
+ if (oldHandler) {
+ if (throwable instanceof RuntimeException) {
+ throw (RuntimeException) throwable;
+ } else if (throwable instanceof Error) {
+ throw (Error) throwable;
+ } else {
+ throw new RuntimeException("Unexpected checked exception
caught in the uncaught exception handler", throwable);
+ }
+ } else {
+ handleStreamsUncaughtException(throwable, t -> SHUTDOWN_CLIENT);
+ }
+ }
+
+ private void handleStreamsUncaughtException(final Throwable throwable,
+ final
StreamsUncaughtExceptionHandler streamsUncaughtExceptionHandler) {
+ final StreamsUncaughtExceptionHandler.StreamThreadExceptionResponse
action = streamsUncaughtExceptionHandler.handle(throwable);
+ if (oldHandler) {
+ log.warn("Stream's new uncaught exception handler is set as well
as the deprecated old handler." +
+ "The old handler will be ignored as long as a new handler
is set.");
+ }
+ switch (action) {
+ case SHUTDOWN_CLIENT:
+ log.error("Encountered the following exception during
processing " +
+ "and the registered exception handler opted to " +
action + "." +
+ " The streams client is going to shut down now. ",
throwable);
+ close(Duration.ZERO);
+ break;
+ case SHUTDOWN_APPLICATION:
+ if (throwable instanceof Error) {
+ log.error("This option requires running threads to shut
down the application." +
+ "but the uncaught exception was an Error, which
means this runtime is no " +
+ "longer in a well-defined state. Attempting to
send the shutdown command anyway.", throwable);
+ }
+ if (Thread.currentThread().equals(globalStreamThread) &&
threads.stream().noneMatch(StreamThread::isRunning)) {
+ log.error("Exception in global thread caused the
application to attempt to shutdown." +
+ " This action will succeed only if there is at
least one StreamThread running on this client." +
+ " Currently there are no running threads so will
now close the client.");
+ close(Duration.ZERO);
Review comment:
That's fair. I guess I was thinking less about the inherent meaning of
ERROR vs NOT_RUNNING, and more about not behaving differently in this special
case. ie if there _are_ still StreamThreads running when a user selects
SHUTDOWN_APPLICATION, then we ultimately transition to ERROR. So it strikes me
as a bit odd to transition to NOT_RUNNING just because we didn't happen to have
any threads left.
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