rpc/erpc behaviour
Bogdan Andu <[email protected]> Fri, 25 Feb 2022 10:55:50 +0200
| Newsgroups | gmane.comp.lang.erlang.general |
|---|---|
| Message-ID | <CAP7yTnw-rRX5DFSh_xH=49s=RW4CSJ8BD4Xy+PdHtmHmm9tUSw@mail.gmail.com> |
Hello, While working with rpc and erpc call and cast I noticed a strange behaviour and I don't know if this is intended or not. Basically, a call to a Module.function on a local node, :'node1', creates a process sub-tree that stays alive as expected. However if the same cal to Module.function is performed from a remote node with a rpc or erpc call from ;'node2': (node2)> :rpc.cast(:'node1', Elixir.Module, :function, [args]) the process sub-tree created by Module.function on :'node1' dies . I have tried every variant: :rpc.cast/call, :erpc.cast/call, even :erpc.send_request/wait_response. Those calls are made from between nodes running as Elixir nodes. Nodes are Erlang 24 and Elixir 1.12.2 (:'node2') and Elixir 1.13.0 (:'node1') The solution I founded is to use a Genserver which apparently keeps the process sub-tree alive. Is it normal that rpc calls cast ro call to end the function on the remote node even if it has the side effects of starting process sub-tree? Why is that happening? Is that normal? From the manual page: https://www.erlang.org/doc/man/rpc.html#call-5 "... It is used for collecting information on a remote node, or for running a function with some *specific side effects *on the remote node." Those side effects would mean in my case that the process sub-tree to remain alive to use that as a service but then again, that side effect disappears once the :rpc.cast/call ends. I made a little test: I put a :timer.sleep(10_000) at the end of Module.function and for 10 seconds the process sub-tree is alive, after that it is killed as the function invoked remotely ends. I want to invoke that function as a library call, not as a GenServer call. How can I do that? I want to wrap in GenServer locally the rpc calls to remote node function as a library call. Cheers, Bogdan