erlang进程监控：link和monitor

清疚 2022-01-14 05:23 150阅读 0赞

[2019独角兽企业重金招聘Python工程师标准>>> ][2019_Python_] ![hot3.png][]

### 1. 进程双向监控-Link ###

--------------------

1.  link方式可以建立进程之间的双向链接关系，当其中一个进程退出时，另一个进程会收到该进程退出的消息。
2.  代码
    
        -module(test).
        -export([start/0]).
        
        start() ->
            Pid = spawn(fun() ->loop() end),
            Pid2 = spawn(fun() ->loop_link(Pid) end),
            io:format("Pid ~p~nPid2 ~p~n", [Pid,Pid2]).
        
        loop_link(Pid) ->
            process_flag(trap_exit, true),
            erlang:link(Pid),
            receive
                Msg ->
                    io:format("pid exit: ~p~n", [Msg])
            end.
        
        loop() ->
            process_flag(trap_exit, true),
            receive
                Msg ->
                    io:format("pid2 exit: ~p~n", [Msg])
        end.
3.  解除link监控用erlang:unlink(Pid)

### 2. 进程单向监控-Monitor ###

--------------------

1.  Monitor方式则实现进程的单向监控，当被监控进程退出时，监控进程会收到该进程退出的消息。
2.  代码
    
        -module(test).
        
        -export([start/0]).
        
        start() ->
            Pid = spawn(fun() ->loop() end),
            Pid3 = spawn(fun() ->loop_monitor(Pid) end),
            io:format("Pid ~p~nPid3 ~p~n", [Pid,Pid3]).
        
        loop_monitor(Pid) ->
            _MonitorRef = erlang:monitor(process, Pid),
            receive
                Msg ->
                    io:format("pid exit: ~p~n", [Msg])
            end.
        
        loop() ->
            receive
                Msg ->
                    io:format("pid3 exit: ~p~n", [Msg])
            end.
3.  解除monitor监控用erlang:demonitor(MonitorRef)

### 3. 如果进程是以 normal 方式退出，erlang将不会发出进程退出通知 ###

转载于:https://my.oschina.net/shadowolf/blog/1593758

[2019_Python_]: https://my.oschina.net/u/2663968/blog/3061697
[hot3.png]: /images/20220114/098fbb18c529418b8dca93997a9ab6cf.png