问题描述
是否有一种简单的方法来获取以 erlang:send_after
, erlang:apply_after $ c $开始的所有当前等待计时器的列表c>等在Erlang中?
Is there a simple way to get a list of all currently waiting timers started with erlang:send_after
, erlang:apply_after
, etc. in Erlang?
推荐答案
出于调试目的,您可以使用 dbg
:)。
For debugging purposes you can use dbg
:).
首先创建一个ets表,该表将存储所有计时器引用。
First create an ets table which will store all timer references.
1> ets:new(timer_dbg, ['public', 'named_table', 'bag']).
timer_dbg
然后创建一个dbg处理程序函数,该函数检查从erlang返回的调用:send_after ,并将返回的计时器参考保存到表中
Then create a dbg handler function, which checks for calls returning from erlang:send_after, and saves the returned timer reference to the table
2> Fun = fun({'trace', _Pid, 'return_from', {erlang, send_after, 3}, Ref}, []) ->
2> ets:insert(timer_dbg, {Ref}), [];
2> (_Msg, []) ->
2> []
2> end.
#Fun<erl_eval.12.113037538>
将该函数设置为跟踪处理程序。同时在所有进程上启用对 erlang:send_after()
的调用
Set the function as trace handler. Also enable matching on the call to erlang:send_after()
on all processes
3> dbg:tracer('process', {Fun, []}).
{ok,<0.35.0>}
4> dbg:p('all', 'c').
{ok,[{matched,nonode@nohost,26}]}
5> dbg:tpl(erlang, send_after, [{'_', [], [{'return_trace'}]}]).
{ok,[{matched,nonode@nohost,1},{saved,1}]}
对 erlang:send_after()
6> erlang:send_after(1000, self(), {}).
#Ref<0.0.0.43>
7> erlang:send_after(1000, self(), {}).
#Ref<0.0.0.47>
8> erlang:send_after(1000, self(), {}).
#Ref<0.0.0.51>
最后检查表中是否包含那些引用:
Finally check that the table does contain those references:
9> ets:tab2list(timer_dbg).
[{#Ref<0.0.0.51>},{#Ref<0.0.0.43>},{#Ref<0.0.0.47>}]
这样,您将存储由任何调用 erlang:send_after()
的进程创建的所有计时器引用。 。您可以在 erlang:read_timer()
上映射它们,以过滤活动计时器。
This way you will store all timer references ever created by any process ever calling erlang:send_after()
. You can map them over erlang:read_timer()
to filter the alive timers.
您可以跟踪对 send_after
。也可以在 cancel_timer
上进行匹配,并从表中手动删除已取消的引用。
You can trace calls to send_after
in a similar manner. It is also possible to match on cancel_timer
and manually remove the cancelled references from the table.
此外,如果您没有消息密集型应用程序,您应该能够匹配那些计时器触发的消息和/或功能,并从列表中删除过期的引用。
Also, if you don't have a message-intensive application, you should be able to match on messages and/or functions triggered by those timers, and remove the expired references from the list.
这篇关于检查Erlang中的活动计时器的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!