Erlang OTP主管崩溃
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03-10-2019 - |
题
我正在浏览Erlang文档,试图了解设置OTP gen_server和主管的基础知识。每当我的gen_server崩溃时,我的主管也会崩溃。实际上,每当我在命令行上有错误时,我的主管都会崩溃。
我希望gen_server崩溃时会重新启动。我希望命令行错误有 没有任何轴承 在我的服务器组件上。我的主管根本不应该崩溃。
我与之合作的代码是基本的“回声服务器”,它与您发送的任何内容一起回复,并且最多最多可重新启动Echo_server的主管(One_For_One)。我的代码:
echo_server.erl
-module(echo_server).
-behaviour(gen_server).
-export([start_link/0]).
-export([echo/1, crash/0]).
-export([init/1, handle_call/3, handle_cast/2]).
start_link() ->
gen_server:start_link({local, echo_server}, echo_server, [], []).
%% public api
echo(Text) ->
gen_server:call(echo_server, {echo, Text}).
crash() ->
gen_server:call(echo_server, crash)..
%% behaviours
init(_Args) ->
{ok, none}.
handle_call(crash, _From, State) ->
X=1,
{reply, X=2, State}.
handle_call({echo, Text}, _From, State) ->
{reply, Text, State}.
handle_cast(_, State) ->
{noreply, State}.
echo_sup.erl
-module(echo_sup).
-behaviour(supervisor).
-export([start_link/0]).
-export([init/1]).
start_link() ->
supervisor:start_link(echo_sup, []).
init(_Args) ->
{ok, {{one_for_one, 5, 60},
[{echo_server, {echo_server, start_link, []},
permanent, brutal_kill, worker, [echo_server]}]}}.
使用 erlc *.erl
, ,这是一个示例运行:
Erlang R13B01 (erts-5.7.2) [source] [smp:2:2] [rq:2] [async-threads:0] [kernel-p
oll:false]
Eshell V5.7.2 (abort with ^G)
1> echo_sup:start_link().
{ok,<0.37.0>}
2> echo_server:echo("hi").
"hi"
3> echo_server:crash().
=ERROR REPORT==== 5-May-2010::10:05:54 ===
** Generic server echo_server terminating
** Last message in was crash
** When Server state == none
** Reason for termination ==
** {'function not exported',
[{echo_server,terminate,
[{{badmatch,2},
[{echo_server,handle_call,3},
{gen_server,handle_msg,5},
{proc_lib,init_p_do_apply,3}]},
none]},
{gen_server,terminate,6},
{proc_lib,init_p_do_apply,3}]}
=ERROR REPORT==== 5-May-2010::10:05:54 ===
** Generic server <0.37.0> terminating
** Last message in was {'EXIT',<0.35.0>,
{{{undef,
[{echo_server,terminate,
[{{badmatch,2},
[{echo_server,handle_call,3},
{gen_server,handle_msg,5},
{proc_lib,init_p_do_apply,3}]},
none]},
{gen_server,terminate,6},
{proc_lib,init_p_do_apply,3}]},
{gen_server,call,[echo_server,crash]}},
[{gen_server,call,2},
{erl_eval,do_apply,5},
{shell,exprs,6},
{shell,eval_exprs,6},
{shell,eval_loop,3}]}}
** When Server state == {state,
{<0.37.0>,echo_sup},
one_for_one,
[{child,<0.41.0>,echo_server,
{echo_server,start_link,[]},
permanent,brutal_kill,worker,
[echo_server]}],
{dict,0,16,16,8,80,48,
{[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],
[]},
{{[],[],[],[],[],[],[],[],[],[],[],[],[],[],
[],[]}}},
5,60,
[{1273,79154,701110}],
echo_sup,[]}
** Reason for termination ==
** {{{undef,[{echo_server,terminate,
[{{badmatch,2},
[{echo_server,handle_call,3},
{gen_server,handle_msg,5},
{proc_lib,init_p_do_apply,3}]},
none]},
{gen_server,terminate,6},
{proc_lib,init_p_do_apply,3}]},
{gen_server,call,[echo_server,crash]}},
[{gen_server,call,2},
{erl_eval,do_apply,5},
{shell,exprs,6},
{shell,eval_exprs,6},
{shell,eval_loop,3}]}
** exception exit: {{undef,
[{echo_server,terminate,
[{{badmatch,2},
[{echo_server,handle_call,3},
{gen_server,handle_msg,5},
{proc_lib,init_p_do_apply,3}]},
none]},
{gen_server,terminate,6},
{proc_lib,init_p_do_apply,3}]},
{gen_server,call,[echo_server,crash]}}
in function gen_server:call/2
4> echo_server:echo("hi").
** exception exit: {noproc,{gen_server,call,[echo_server,{echo,"hi"}]}}
in function gen_server:call/2
5>
解决方案
来自外壳的问题测试主管是主管过程链接到Shell过程。当gen_server进程崩溃时,退出信号将传播到壳崩溃并重新启动的外壳。
为了避免问题,将这样的问题添加到主管:
start_in_shell_for_testing() ->
{ok, Pid} = supervisor:start_link(echo_sup, []),
unlink(Pid).
其他提示
我建议你 调试/跟踪 您的申请以检查发生了什么。这对于了解如何在OTP中工作非常有帮助。
就您而言,您可能需要做以下操作。
启动示踪剂:
dbg:tracer().
跟踪所有功能呼叫您的主管和您的gen_server:
dbg:p(all,c).
dbg:tpl(echo_server, x).
dbg:tpl(echo_sup, x).
检查过程传递的消息:
dbg:p(new, m).
查看您的流程发生的事情(崩溃等):
dbg:p(new, p).
有关跟踪的更多信息:
http://www.erlang.org/doc/man/dbg.html
http://aloiroberto.wordpress.com/2009/02/23/tracing-erlang-functions/
希望这可以为这种情况和将来的情况有所帮助。
暗示: gen_server行为期望定义和导出回调2;)
更新: 在定义之后 终止/2 从痕迹中可以明显看出坠机的原因。这就是外观:
我们(75)调用崩溃/0功能。 Gen_Server(78)收到了这一点。
(<0.75.0>) call echo_server:crash()
(<0.75.0>) <0.78.0> ! {'$gen_call',{<0.75.0>,#Ref<0.0.0.358>},crash}
(<0.78.0>) << {'$gen_call',{<0.75.0>,#Ref<0.0.0.358>},crash}
(<0.78.0>) call echo_server:handle_call(crash,{<0.75.0>,#Ref<0.0.0.358>},none)
嗯,句柄电话上的问题。我们有一个折磨...
(<0.78.0>) exception_from {echo_server,handle_call,3} {error,{badmatch,2}}
终止功能称为. 。服务器退出,未注册。
(<0.78.0>) call echo_server:terminate({{badmatch,2},
[{echo_server,handle_call,3},
{gen_server,handle_msg,5},
{proc_lib,init_p_do_apply,3}]},none)
(<0.78.0>) returned from echo_server:terminate/2 -> ok
(<0.78.0>) exit {{badmatch,2},
[{echo_server,handle_call,3},
{gen_server,handle_msg,5},
{proc_lib,init_p_do_apply,3}]}
(<0.78.0>) unregister echo_server
主管(77)从Gen_Server接收出口信号,并完成其工作:
(<0.77.0>) << {'EXIT',<0.78.0>,
{{badmatch,2},
[{echo_server,handle_call,3},
{gen_server,handle_msg,5},
{proc_lib,init_p_do_apply,3}]}}
(<0.77.0>) getting_unlinked <0.78.0>
(<0.75.0>) << {'DOWN',#Ref<0.0.0.358>,process,<0.78.0>,
{{badmatch,2},
[{echo_server,handle_call,3},
{gen_server,handle_msg,5},
{proc_lib,init_p_do_apply,3}]}}
(<0.77.0>) call echo_server:start_link()
好吧,它尝试...因为它发生了菲利波所说的话...
另一方面,如果必须从控制台内测试重新启动策略,请使用控制台启动主管并与PMAN核对以杀死该过程。
您会看到PMAN用同一主管PID刷新,但根据您在重新启动策略中设置的Maxr和Maxt的不同Worker PID。