pad-block-deadlock.

Main.java

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

import org.freedesktop.gstreamer.Element;
import org.freedesktop.gstreamer.Gst;
import org.freedesktop.gstreamer.Pad;
import org.freedesktop.gstreamer.Pipeline;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Main {
	private static final Logger log = LoggerFactory.getLogger(Main.class);

	public static void main(String[] args) throws InterruptedException, ExecutionException, TimeoutException {
		Gst.init();

		Pipeline pipeline = (Pipeline) Gst
			.parseLaunch("audiotestsrc name=src ! fakesink sync=false");

		pipeline.play();

		Element src = pipeline.getElementByName("src");
		Pad srcPad = src.getStaticPad("src");

		//noinspection InfiniteLoopStatement
		while (true) {
			log.info("> blocking");
			CompletableFuture<Void> future = new CompletableFuture<>();
			srcPad.block(() -> {
				log.info("= blocked");
				future.complete(null);
				log.info("= completed");
			});
			log.info("< getting");
			future.get(10, TimeUnit.SECONDS);
			log.info("< got");
		}
	}
}