grpc_completion_queue_pluck doesn't return shutdown event

[kishan nerella]

Hello,

I'm using grpc-c library(link) which provides a c-wrapper around the core library. The following is the pseudo code for a unary client call(modified to handle failure cases).

cq = grpc_completion_queue_create();

call = grpc_channel_create_call(cq);

// Start a batch on the call to do an unary RPC.

grpc_call_start_batch(call);

gpr_timespec tout = gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),

                                gpr_time_from_millis(15000, GPR_TIMESPAN));

ev = grpc_completion_queue_pluck(context->gcc_cq, context, tout, NULL);

if (ev.type == GRPC_QUEUE_TIMEOUT &&

    grpc_call_cancel(context->gcc_call, NULL) == GRPC_CALL_OK) {

  gpr_log(GPR_ERROR, "Sync call timedout");

  grpc_completion_queue_shutdown(cq);

  while (grpc_completion_queue_pluck(cq, context,

                                     gpr_inf_past(GPR_CLOCK_REALTIME), NULL)

             .type != GRPC_QUEUE_SHUTDOWN)

    ;

  grpc_completion_queue_destroy(cq);

}

1. Is the above handling of completion queue destruction correct when the RPC times out?

2. Once in a while, I see a case where the grpc_completion_queue_pluck() doesn't return shutdown event ever when a timeout occurs. Can there be a reason this can happen?

Note that in our setup, upto 5 RPCs can be made in parallel on the same client.

Thanks,

Kishan.