[Java][FlightRPC] Java arrow flight server stuck in reader.getDescriptor()

Commencez par FlightStream.java:158, où getDescriptor() attend, puis suivez le chemin Java de doExchange à travers FlightService et UDFProducer.java:266. Comparez ce flux avec l’appel C++ Client_->DoExchange(descriptor) et les éléments jstack fournis dans une configuration multithread. Le travail est terminé lorsque la raison pour laquelle le descriptor future reste non défini est identifiée et qu’une cause reproductible ou une résolution confirmée est documentée.

Describe the usage question you have. Please include as many useful details as possible.

Platform: Ubuntu 20.04.6 LTS
Arrow version: 15.
Client: C++
Server: Java
I have a Java arrow flight server that uses doExchange to read the context, my server code is as follows, I have identified in multiple thread environment, in the tests many calls would stuck at the line FlightDescriptor descriptor = reader.getDescriptor(); in the second time(Which means the first call in the same thread usually is not blocked), and which makes the following requests also stucks.

        log.info("Start to call doExchange.........");
        // Trying to
        try (BufferAllocator allocator = allocatorPool.submit(
            () -> this.allocator.newChildAllocator("exchange", 0, Long.MAX_VALUE)).get()) {
            FlightDescriptor descriptor = reader.getDescriptor();
            List<String> path = descriptor.getPath();
            String type = path.get(0);
            String funcSignature = path.get(1);
           ...

The client code is as follows

std::vector<std::shared_ptr<RecordBatch>> UDFClient::Call(
    const std::vector<std::string>& paths,
    std::shared_ptr<RecordBatch>& batch) const {
  // Create a FlightDescriptor using a path
  FlightDescriptor descriptor = FlightDescriptor::Path(paths);
  auto exchange_result = Client_->DoExchange(descriptor);
  if (!exchange_result.ok()) {
    throw std::runtime_error("Do exchange descriptor: "
            + exchange_result.status().ToString());
  }
  auto exchange = std::move(exchange_result.ValueUnsafe());
  ...

I understand reader.getDescriptor(); is a blocking call that will use future to wait the descriptor sent. Since doExchange in the server has been called, I assume the client auto exchange_result = Client_->DoExchange(descriptor); has been received. I can't figure what could make reader.getDescriptor(); stuck, I am reporting this to the community that want to know is this a bug or there is something I did wrong. Thank you

This happened in the multiple threads environment. We also check the lock with jstack that shows SettableFuture<FlightDescriptor> descriptor is the one not set that caused the lock.

"pool-1-thread-16" #31 prio=5 os_prio=0 tid=0x00007f6d34009000 nid=0x3a19 waiting on condition [0x00007f6d253ea000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x000000076d596180> (a com.google.common.util.concurrent.SettableFuture)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
        at com.google.common.util.concurrent.AbstractFuture.get(AbstractFuture.java:563)
        at com.google.common.util.concurrent.AbstractFuture$TrustedFuture.get(AbstractFuture.java:110)
        at org.apache.arrow.flight.FlightStream.getDescriptor(FlightStream.java:158)
        at com.bytedance.dp.udf.UDFProducer.doExchange(UDFProducer.java:266)
        at org.apache.arrow.flight.FlightService.lambda$doExchangeCustom$2(FlightService.java:382)
        at org.apache.arrow.flight.FlightService$$Lambda$65/298187580.run(Unknown Source)
        at io.grpc.Context$1.run(Context.java:566)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

Component(s)

C++, FlightRPC, Java