Both my server and client are implemented in python now, Java Client
may be in the future.
Back pressure works, but not totally in control.
Is there a way to configure how much memory used to read ahead for
each grpc stream?
For example, the client is calling do_get, then the client wants to
limit the memory of FlightStreamReader, since the downstream
processing is a time/memory consuming task. For its best option only
read one record batch ahead with specified batch_size so that the
minimum memory is used for streaming.
Is "GRPC_ARG_HTTP2_STREAM_LOOKAHEAD_BYTES" used for that purpose?
`generic_options=[("grpc.http2.lookahead_bytes", 100000)]`
It seems not to take effect. I wrote a server sending the same record
batch continuously 100 times, the client takes 1 sec to process each
record batch read from do_get, no matter what value set, the server
blocks at writing 14th/25th record batch...David Li <lidav...@apache.org> 于2023年7月7日周五 22:26写道： > > gRPC has backpressure built in. Is your server in Java or Python/C++? > > If in Java, the server needs to explicitly poll isReady to respect > backpressure. (This is rather wasteful, yes, and this will artificially > throttle your peak bandwidth because of a long-standing flaw in gRPC-Java.) > > If in Python/C++, the backpressure should be automatic (write calls will > block), so the client should just make sure not to read from the reader until > it actually wants data (there are lower-level options to tweak this, IIRC) > > On Thu, Jul 6, 2023, at 23:18, Wenbo Hu wrote: > > Hi, > > I'm using arrow flight to transfer data in distributed system, but > > the lightning speed makes both client and server faces out of memory > > issue. > > For do_put and do_exchange method, the protocol provides stream > > metadata reader/writer for client/server exchange control messages > > along data stream. > > But do_get only returns a FlightDataStream without any extra > > control message can be used to communicate with each other. > > Also, the returned FlightDataStream is unaware of client > > canceling, while java has a cancel callback. > > My solution is to use do_exchange to replace do_get for client > > download data, or is there any better way to implement that? > > > > -- > > --------------------- > > Best Regards, > > Wenbo Hu, -- --------------------- Best Regards, Wenbo Hu,
