erlang 故障排查工具

 系统级别perf top, dstat -tam, vtune 都能很好分析beam 瓶颈,本文主要erlang 级别排查:

1. 反编译

   确认线上运行代码是否正确,reltools没掌握好,升级偶尔出现问题

decompile(Mod) ->
    {ok,{_,[{abstract_code,{_,AC}}]}} = beam_lib:chunks(code:which(Mod), [abstract_code]),
    io:format("~s~n", [erl_prettypr:format(erl_syntax:form_list(AC))]).

 

2. 进程栈

    类似于jstack,发现大量进程挂起,进程数过高,运行慢,hang住等问题用到

pstack(Reg) when is_atom(Reg) ->
    case whereis(Reg) of
        undefined -> undefined;
        Pid -> pstack(Pid)
    end;
pstack(Pid) ->
    io:format("~s~n", [element(2, process_info(Pid, backtrace))]).

 

3. etop

  分析内存、cpu占用进程,即使数十w进程node 也能正常使用

%进程CPU占用排名
etop() ->
    spawn(fun() -> etop:start([{output, text}, {interval, 10}, {lines, 20}, {sort, reductions}]) end).

%进程Mem占用排名
etop_mem() ->
    spawn(fun() -> etop:start([{output, text}, {interval, 10}, {lines, 20}, {sort, memory}]) end).

%停止etop
etop_stop() ->
    etop:stop().

 

4. gc all

   进程内存过高时,来一发,看看是内存泄露还是gc不过来

% 对所有process做gc
gc_all() ->
    [erlang:garbage_collect(Pid) || Pid <- processes()].

 

5.  fprof

% 对MFA 执行分析,会严重减缓运行,建议只对小量业务执行
% 结果:
% fprof 结果比较详细,能够输出热点调用路径
fprof(M, F, A) ->
    fprof:start(),
    fprof:apply(M, F, A),
    fprof:profile(),
    fprof:analyse(),
    fprof:stop().

 

6. eprof

% 对整个节点内所有进程执行eprof, eprof 对线上业务有一定影响,慎用!
% 建议TimeoutSec<10s,且进程数< 1000,否则可能导致节点crash
% 结果:
% 输出每个方法实际执行时间(不会累计方法内其他mod调用执行时间)
% 只能得到mod - Fun 执行次数 执行耗时
eprof_all(TimeoutSec) ->
    eprof(processes() -- [whereis(eprof)], TimeoutSec).

eprof(Pids, TimeoutSec) ->
    eprof:start(),
    eprof:start_profiling(Pids),
    timer:sleep(TimeoutSec),
    eprof:stop_profiling(),
    eprof:analyze(total),
    eprof:stop().

 

7. scheduler usage

% 统计下1s每个调度器CPU的实际利用率(因为有spin wait、调度工作, 可能usage 比top显示低很多)
scheduler_usage() ->
    scheduler_usage(1000).

scheduler_usage(RunMs) ->
    erlang:system_flag(scheduler_wall_time, true),
    Ts0 = lists:sort(erlang:statistics(scheduler_wall_time)),
    timer:sleep(RunMs),
    Ts1 = lists:sort(erlang:statistics(scheduler_wall_time)),
    erlang:system_flag(scheduler_wall_time, false),
    Cores = lists:map(fun({{I, A0, T0}, {I, A1, T1}}) ->
                    {I, (A1 - A0) / (T1 - T0)} end, lists:zip(Ts0, Ts1)),
    {A, T} = lists:foldl(fun({{_, A0, T0}, {_, A1, T1}}, {Ai,Ti}) ->
                    {Ai + (A1 - A0), Ti + (T1 - T0)} end, {0, 0}, lists:zip(Ts0, Ts1)),
    Total = A/T,
    io:format("~p~n", [[{total, Total} | Cores]]).

 

8.  进程调度

% 统计下1s内调度进程数量(含义:第一个数字执行进程数量,第二个数字迁移进程数量)
scheduler_stat() ->
    scheduler_stat(1000).

scheduler_stat(RunMs) ->
    erlang:system_flag(scheduling_statistics, enable),
    Ts0 = erlang:system_info(total_scheduling_statistics),
    timer:sleep(RunMs),
    Ts1 = erlang:system_info(total_scheduling_statistics),
    erlang:system_flag(scheduling_statistics, disable),
    lists:map(fun({{Key, In0, Out0}, {Key, In1, Out1}}) ->
                {Key, In1 - In0, Out1 - Out0} end, lists:zip(Ts0, Ts1)).

 

9. trace 日志

  会把mod 每次调用详细MFA log 下来,args 太大就不好看了

%trace Mod 所有方法的调用
trace(Mod) ->
    dbg:tracer(),
    dbg:tpl(Mod, '_', []),
    dbg:p(all, c).

%trace Node上指定 Mod 所有方法的调用, 结果将输出到本地shell
trace(Node, Mod) ->
    dbg:tracer(),
    dbg:n(Node),
    dbg:tpl(Mod, '_', []),
    dbg:p(all, c).

%停止trace
trace_stop() ->
    dbg:stop_clear().

 

10. 内存高OOM 排查工具

  etop 无法应对10w+ 进程节点, 下面代码就没问题了;找到可疑proc后通过pstack、message_queu_len 排查原因

  proc_mem_all(SizeLimitKb) ->
      Procs = [{undefined, Pid} || Pid<- erlang:processes()],
      proc_mem(Procs, SizeLimitKb).

  proc_mem(SizeLimitKb) ->
      Procs = [{Name, Pid} || {_, Name, Pid, _} <- release_handler_1:get_supervised_procs(),
                              is_process_alive(Pid)],
      proc_mem(Procs, SizeLimitKb).

  proc_mem(Procs, SizeLimitKb) ->
      SizeLimit = SizeLimitKb * 1024,
      {R, Total} = lists:foldl(fun({Name, Pid}, {Acc, TotalSize}) ->
          case erlang:process_info(Pid, total_heap_size) of
              {_, Size0} ->
                  Size = Size0*8,
                  case Size > SizeLimit of
                      true -> {[{Name, Pid, Size} | Acc], TotalSize+Size};
                      false -> {Acc, TotalSize}
                  end;
              _ -> {Acc, TotalSize}
              end
          end, {[], 0}, Procs),
      R1 = lists:keysort(3, R),
      {Total, lists:reverse(R1)}.

 

posted @ 2014-12-07 11:26  LittlePeng  阅读(4907)  评论(0编辑  收藏  举报