ClosedChannelException when trying to write to Cloud Bigtable in GAE - google-app-engine

Question

I'm trying to write to cloud bigtable in my app engine servlet. I copied the BigTableHelper from https://github.com/GoogleCloudPlatform/cloud-bigtable-examples/blob/master/java/managed-vm-gae/gae-bigtable-hello/src/main/java/com.example.cloud.bigtable.helloworld/BigtableHelper.java, and in my servlet I simply did the following.
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws IOException {
try (Table t = BigtableHelper.getConnection().getTable(BigtableHelper.TEST_TABLE)) {
Put put = new Put(Bytes.toBytes("row1"));
put.addColumn(BigtableHelper.RAW_UPDATE_FAMILY, BigtableHelper.RAW_UPDATE_QUALIFIER,
Bytes.toBytes("testdata"));
t.put(put);
} catch (IOException e) {
log("writeToBigtable", e);
}
}
The put failed with error.
java.io.IOException: Failed to perform operation. Operation='put', projectId='myprojectid', tableName='test_table', rowKey='row1' at com.google.cloud.bigtable.hbase.BigtableTable.put(BigtableTable.java:288) at ...
Caused by: com.google.bigtable.repackaged.com.google.common.util.concurrent.UncheckedExecutionException: io.grpc.StatusRuntimeException: UNKNOWN at io.grpc.stub.Calls.getUnchecked(Calls.java:117) at io.grpc.stub.Calls.blockingUnaryCall(Calls.java:129) at com.google.cloud.bigtable.grpc.BigtableGrpcClient.mutateRow(BigtableGrpcClient.java:210) at com.google.cloud.bigtable.hbase.BigtableTable.put(BigtableTable.java:285) ... 32 more
Caused by: io.grpc.StatusRuntimeException: UNKNOWN at io.grpc.Status.asRuntimeException(Status.java:428) at io.grpc.stub.Calls$UnaryStreamToFuture.onClose(Calls.java:324) at io.grpc.ChannelImpl$CallImpl$ClientStreamListenerImpl$3.run(ChannelImpl.java:402) at io.grpc.SerializingExecutor$TaskRunner.run(SerializingExecutor.java:154) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) ... 1 more
Caused by: java.nio.channels.ClosedChannelException
BigtableHelper.getConnection() didn't throw an exception, I assume the it connect successfully. Is there anything wrong with the put statement? What could cause this problem? Thanks!

Answer 1

We have updated examples for interacting with Cloud Bigtable from Google App Engine Flex and Standard using Java 8 here:
https://github.com/googlecloudplatform/java-docs-samples/tree/master/appengine-java8/bigtable
https://github.com/GoogleCloudPlatform/cloud-bigtable-examples/tree/master/java/gae-flexible-helloworld