我看过一篇关于Erlang select接收机制的文章，在文章的最后有一个结论：“邮件从邮箱移到保存队列，然后在匹配的邮件到达后移回邮箱”。我已经尝试了文章中显示的例子，但我无法得到相同的结果。这是我的代码，我的erlang/otp版本是21。

shell1:
(aaa@HW0003727)1> register(shell, self()).
true
(aaa@HW0003727)2> shell ! c, shell ! d.
d
(aaa@HW0003727)3> process_info(whereis(shell),messages).
{messages,[c,d]}.
(aaa@HW0003727)4> receive a -> 1; b -> 2 end.

shell2:
(aaa@HW0003727)1> process_info(whereis(shell),messages).
{messages,[c,d]}
(aaa@HW0003727)2> process_info(whereis(shell)).          
[{registered_name,shell},
 {current_function,{prim_eval,'receive',2}},
 {initial_call,{erlang,apply,2}},
 {status,waiting},
 {message_queue_len,2},
 {links,[<0.113.0>]},
 {dictionary,[]},
 {trap_exit,false},
 {error_handler,error_handler},
 {priority,normal},
 {group_leader,<0.112.0>},
 {total_heap_size,4212},
 {heap_size,1598},
 {stack_size,30},
 {reductions,13906},
 {garbage_collection,[{max_heap_size,#{error_logger => true,kill => true,size => 0}},
                      {min_bin_vheap_size,46422},
                      {min_heap_size,233},
                      {fullsweep_after,65535},
                      {minor_gcs,1}]},
 {suspending,[]}]

的article。