查询Erlang进程的状态?
Erlang中的一种常见模式是维护状态的递归循环:查询Erlang进程的状态?,erlang,Erlang,Erlang中的一种常见模式是维护状态的递归循环: loop(State) -> receive Msg -> NewState = whatever(Msg), loop(NewState) end. Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false] Eshell V5.6.5 (abort with
loop(State) ->
receive
Msg ->
NewState = whatever(Msg),
loop(NewState)
end.
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
有没有办法用bif或跟踪之类的工具来查询正在运行的进程的状态?由于崩溃消息会显示“…当状态为…”并显示崩溃进程的状态,我认为这很容易,但我很失望,因为我没有找到一个bif来执行此操作
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
因此,我认为使用dbg模块的跟踪可以做到这一点。不幸的是,我相信因为这些循环是尾部调用优化的,dbg将只捕获对函数的第一个调用
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
有什么解决办法吗?看起来你在无中生有地解决问题。erlang:process_info/1提供了足够的调试信息。如果您确实需要循环函数参数,为什么不将其返回给调用者,以响应您自己定义的一条特殊消息
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
更新:
只是为了澄清术语。在语言级别上最接近“进程状态”的是进程字典,它的使用是非常不鼓励的。可以通过erlang:process\u info/1或erlang:process/2查询。
您实际需要的是跟踪进程的本地函数调用及其参数:
-module(ping).
-export([start/0, send/1, loop/1]).
start() ->
spawn(?MODULE, loop, [0]).
send(Pid) ->
Pid ! {self(), ping},
receive
pong ->
pong
end.
loop(S) ->
receive
{Pid, ping} ->
Pid ! pong,
loop(S + 1)
end.
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
控制台:
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
Erlang(BEAM)emulator 5.6.5版[源代码][smp:2][异步线程:0][内核轮询:false]
Eshell V5.6.5(使用^G中止)
1> l(平)。
{模块,ping}
2> erlang:trace(all,true,[call])。
23
3> erlang:trace_模式({ping,''.','.'},true,[local])。
5.
4> Pid=ping:start()。
5> ping:发送(Pid)。
庞
6> 刷新()。
Shell获取了{trace,,call,{ping,loop,[0]}
Shell获取了{trace,,call,{ping,loop,[1]}
好啊
7>
据我所知,您无法将参数传递给本地调用的函数。我希望有人能证明我错了
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
-module(loop).
-export([start/0, loop/1]).
start() ->
spawn_link(fun () -> loop([]) end).
loop(State) ->
receive
Msg ->
loop([Msg|State])
end.
如果要跟踪此模块,请在shell中执行以下操作
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
dbg:tracer().
dbg:p(new,[c]).
dbg:tpl(loop, []).
sys:get_status(list_to_pid("<0.1012.0>")).
使用此跟踪设置,您可以看到本地调用(tpl中的“l”表示也将跟踪本地调用,而不仅仅是全局调用)
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
5>Pid=loop:start()。
()调用循环:'-start/0-fun-0-'/0
()调用循环:循环/1
6> Pid!福。
()调用循环:循环/1
福
如您所见,只包括电话。看不到任何争论
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
我的建议是将调试和测试的正确性建立在发送的消息上,而不是进程中保存的状态上。也就是说,如果您向流程发送了一组消息,请断言它做了正确的事情,而不是它有一组特定的值
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
当然,您也可以在代码中临时添加一些
erlang:display(State)
调用。可怜的人的调试。如果您的进程正在使用OTP,这就足够了
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
您提到的错误消息由SASL显示。SASL是OTP中的错误报告守护进程
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
示例代码中引用的状态只是尾部递归函数的一个参数。除了跟踪BIF之外,没有任何方法可以提取它。我想这在生产代码中不是一个合适的解决方案,因为跟踪仅用于调试目的
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
适当的、经过行业测试的解决方案是在您的项目中广泛使用OTP。然后,您可以充分利用SASL错误报告,rb
模块收集这些报告,sys
-检查正在运行的OTP兼容进程的状态,proc_lib
-使短期进程符合OTP,等等
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
{status,Pid,_,[_,_,_,_,[_,_,{data,[{_,State}]}]]} = sys:get_status(Pid).
这就是我用来获取gen_服务器状态的方法。(试图将其作为注释添加到上面的回复中,但无法正确设置格式。)这是一个可以在shell中使用的“oneliner”
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
dbg:tracer().
dbg:p(new,[c]).
dbg:tpl(loop, []).
sys:get_status(list_to_pid("<0.1012.0>")).
sys:get_status(list_to_pid(“”))。
它可以帮助您将pid字符串转换为pid。如果您使用OTP,那么有一个比所有这些更好的答案:
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>
可能当时还不存在。因为erlang有所有这些很酷的设备来检查和调试实时系统,所以我希望有一些通用的东西。你不认为知道进程的状态对调试有用吗?为什么任何语言中的调试器都有很多用于检查和与变量状态交互的功能?太棒了。这就是我一直在寻找的。我想让我的孩子同时使用的http请求(使用ibrowse)的数量保持在100以下。在本例中,我有一个使用计数器的节流过程。我担心计数器将与正在计数的资源不同步,应用程序将越来越慢。所以,问题是我不能轻易地测试它是否做了正确的事情。程序将继续正常运行,只是速度会慢一些
Erlang (BEAM) emulator version 5.6.5 [source] [smp:2] [async-threads:0] [kernel-poll:false]
Eshell V5.6.5 (abort with ^G)
1> l(ping).
{module,ping}
2> erlang:trace(all, true, [call]).
23
3> erlang:trace_pattern({ping, '_', '_'}, true, [local]).
5
4> Pid = ping:start().
<0.36.0>
5> ping:send(Pid).
pong
6> flush().
Shell got {trace,<0.36.0>,call,{ping,loop,[0]}}
Shell got {trace,<0.36.0>,call,{ping,loop,[1]}}
ok
7>