@Override
                           public void onError(Throwable throwable) {
                               concurrentStreamObserverNumber.addAndGet(-1);
                               Status status = Status.fromThrowable(throwable);
                               if (Status.CANCELLED.getCode() == status.getCode()) {
                                   if (log.isDebugEnabled()) {
                                       log.debug(throwable.getMessage(), throwable);
                                   }
                                   return;
                               } else if (Status.RESOURCE_EXHAUSTED.getCode() == status.getCode()) {
                                   if (System.currentTimeMillis() - lastRemoteResourceExhaustedTime > 120_000) {
                                       // Only output the log every 120 seconds.
                                       log.warn(throwable.getMessage(), throwable);
                                       lastRemoteResourceExhaustedTime = System.currentTimeMillis();
                                   }
                                   return;
                               }
                               log.error(throwable.getMessage(), throwable);
                           }
Create a gRPC stream observer to sending stream data, one stream observer could send multiple stream data by a
single consume. The max number of concurrency allowed at the same time is 10.

@return stream observer
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/remote/client/GRPCRemoteClient.java