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July 25th, 2013

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2013-07-24 23:54:06 =ERROR REPORT====
** Generic server <0.31760.980> terminating
** Last message in was {‘EXIT’,<0.29814.980>,killed}
** When Server state == {state,”app873″,false,172683,33,<<"app873">>,<0.29814.980>,ump_proxy_session,1,[59,32,204,78,86,208,242,122,240,207,269,79,80],[],2,true,<<>>,0,0,{conn_info,{10,246,161,112},10145,”app873″,”8813684fc05fb6cd”},<0.31762.980>,1,{conn_info,{172,18,134,8},10085,”app873″,”8813684fc05fb6cd”},ump_proxy_cherly_server,<0.31763.980>,1,undefined,<<>>,false,true,[],{dict,2,16,16,8,80,48,{[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[]},{{[],[[{session,names},103,98,107]],[],[],[],[],[],[],[[{session,”character_set_results”},78,85,76,76]],[],[],[],[],[],[],[]}}},1,0,0,0,0,0,200,1374681206757732}
** Reason for termination ==
** killed

其中Reason是killed, 有点困扰。

我们知道在热升级的时候会purge用旧代码的进程, purge的时候发现有必要就会exit(P, kill)让进程死亡,但是怎么kill变成了killed呢?


eval({purge, Modules}, EvalState) ->
    % Now, if there are any processes still executing old code, OR
    % if some new processes started after suspend but before load,
    % these are killed.
    lists:foreach(fun(Mod) -> code:purge(Mod) end, Modules),

do_purge([P|Ps], Mod, Purged) ->
    case erlang:check_process_code(P, Mod) of
        true ->
            Ref = erlang:monitor(process, P),
            exit(P, kill),
                {'DOWN',Ref,process,_Pid,_} -> ok
            do_purge(Ps, Mod, true);
        false ->
            do_purge(Ps, Mod, Purged)

release_handler最终确实是调用了exit(P, kill)杀人,可是为什么对端收到killed死因呢?


static ERTS_INLINE int
send_exit_signal(Process *c_p,          /* current process if and only                                                    
                                           if reason is stored on it */
                 Eterm from,            /* Id of sender of signal */
                 Process *rp,           /* receiving process */
                 ErtsProcLocks *rp_locks,/* current locks on receiver */
                 Eterm reason,          /* exit reason */
                 Eterm exit_tuple,      /* Prebuild exit tuple                                                            
                                           or THE_NON_VALUE */
                 Uint exit_tuple_sz,    /* Size of prebuilt exit tuple                                                    
                                           (if exit_tuple != THE_NON_VALUE) */
                 Eterm token,           /* token */
                 Process *token_update, /* token updater */
                 Uint32 flags           /* flags */
 Eterm rsn = reason == am_kill ? am_killed : reason;



exit(Pid, Reason) -> true


Pid = pid() | port()
Reason = term()
Sends an exit signal with exit reason Reason to the process or port identified by Pid.

The following behavior apply if Reason is any term except normal or kill:

If Pid is not trapping exits, Pid itself will exit with exit reason Reason. If Pid is trapping exits, the exit signal is transformed into a message {‘EXIT’, From, Reason} and delivered to the message queue of Pid. From is the pid of the process which sent the exit signal. See also process_flag/2.

If Reason is the atom normal, Pid will not exit. If it is trapping exits, the exit signal is transformed into a message {‘EXIT’, From, normal} and delivered to its message queue.

If Reason is the atom kill, that is if exit(Pid, kill) is called, an untrappable exit signal is sent to Pid which will unconditionally exit with exit reason killed.




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  1. littlepeng
    July 20th, 2014 at 22:14 | #1

    以前一直也困扰 exit(Pid, kill) 过去变成了killed。

    emulator Discarding message {stop,,0} from to in an old incarnation (3) of this node (1)
    翻了下beam源码,会输出这个错误的两处都是 to 不是本地节点时,这个日志明显是本地的Pid,搞不明白挖。

    littlepeng Reply:

    好吧,评论里面pid 被html编码了,我再发一遍 emulator Discarding message {stop,<0.24230.6>,0} from <0.24230.6> to <0.24726.7195> in an old incarnation (3) of this node (1)

    Yu Feng Reply:

    我有一篇写old incarnation的博客

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