file_server_2 is wedged

[Mikael Pettersson]

On Thu, Sep 10, 2020 at 5:08 PM Matthew Evans <mattevans123@REDACTED> wrote:
>
> Hi,
>
> We have a system running R21 where file_server_2 is stuck in a nif call. Here's the stack trace.
>
> root@REDACTED:~# doErlangFun "erlang:process_info(whereis(file_server_2),current_stacktrace)"
> {current_stacktrace,[{prim_file,read_info_1,3,[]},
>                      {file_server,handle_call,3,
>                                   [{file,"file_server.erl"},{line,146}]},
>                      {gen_server,try_handle_call,4,
>                                  [{file,"gen_server.erl"},{line,661}]},
>                      {gen_server,handle_msg,6,
>                                  [{file,"gen_server.erl"},{line,690}]},
>                      {proc_lib,init_p_do_apply,3,
>                                [{file,"proc_lib.erl"},{line,249}]}]}
>
>
> The message queue of file_server_2 keeps growing.
>
> We have the async thread pool set to 25.
>
> Has anyone seen this before?

Not this one specifically, but the file server has a very long history
of blocking processes.  We often use prim_file instead to avoid that
problem.  It may be better in newer OTP versions.