Dtrace为内存溢出？ [英] Dtrace for memory overflow?

问题描述

我想写一个Dtrace，以便我可以分析 overflow_error 是否正在执行的进程
中发生。我只是知道这是一个错误抛出 std :: overflow_error 。我不知道如何写一个D迹。我需要一些初学者指南，如果有人可以让我知道如何写它。我正在运行的进程名是 superbug_returns 。我如何写一个D-Trace分析如果上述情况发生或不是？我正在研究solaris

I want to write a Dtrace so that i can analyse if overflow_error is happening in a process i am executing . I just know that this is an error thrown as std::overflow_error. I don't have much idea about how to write a D-Trace . I need some beginner guide and if someone can let me know how to write it . The process name i am running is say superbug_returns . How can i write a D-Trace for it analyzing if above scenario is happening or not? I am working on solaris

推荐答案

我第二个建议尝试调试器与此 - 通常有一个命令， C ++ - 异常。

I second the suggestion to try the debugger with this - there's usually a command to break-on-C++-exception. It's simpler to go that way.

如果你坚持使用DTrace：

几年前，Sun发布了白皮书如何使用DTrace与C ++ - 阅读。

If you insist on DTrace:
A few years ago, Sun published a whitepaper how to use DTrace with C++ - read that.

将这里描述的技术应用到跟踪异常用例程序是不平凡的，不幸的是，因为异常抛出/处理是在C ++运行时，并通过内部（非曝光）函数调用。在gcc编译的代码中， throw ... 变成 __ cxa_throw（...），而在SunStudio编译的代码使用不同的名称管理方案）一个函数（unmangled / mangled）：

It's not trivial to apply the techniques described there to the "trace exceptions" usecase, unfortunately, because exception throwing/handling is in the C++ runtime and done through internal (nonexposed) function calls. In gcc-compiled code, throw ... becomes __cxa_throw(...) whereas in SunStudio-compiled code (which uses a different name mangling scheme) a function (unmangled / mangled):

void __Crun::ex_throw(void*,const __Crun::static_type_info*,void(*)(void*))

__1cG__CrunIex_throw6Fpvpkn0AQstatic_type_info_pF1_v_v_

被调用。注意这取决于你的编译器版本; SunStudio在过去的某个时候改变了他们的修改方案/ C ++运行时。在这两种情况下， std :: ... 将作为参数传递，所以你想要DTrace为一个特定的异常类只有你需要二次过滤（一个D探测谓词，用于测试抛出的异常是否是您感兴趣的异常）。你需要找出上面的函数的参数对应于 std :: overflow 被抛出和过滤。

不你的实际目标文件，我不能给更多的建议。首先，请尝试：

is called. Note that this depends on your compiler version; SunStudio changed their mangling scheme / C++ runtime at some point in the past. In both cases though, std::... would be passed as argument, so it you'd want to DTrace for a specific exception class only you'd need secondary filtering (a D probe predicate that tests whether the exception thrown is really the one you're interested in). You'd need to find out what args to the above function[s] correspond to std::overflow being thrown and filter for those.
Without your actual object file, I can't give more advice than that. For a start, try:

gcc：

dtrace -n '
    pid<your-process-pid>::__cxa_throw:entry
    {
        @exloc[ustack()] = count();
    }'

SunStudio：

SunStudio:

dtrace -n '
    pid<your-process-pid>::__1cG__CrunIex_throw6Fpvpkn0AQstatic_type_info_pF1_v_v_:entry
    {
        @exloc[ustack()] = count();
    }'

在代码中查找抛出异常的位置（Ctrl + C终止DTrace给你的统计）。然后从那里进行迭代（尝试转储参数，看看是否可以标识 std :: overflow ，通过添加一个 / arg0 == ... / 或类似于探针）。

to find places in your code where exceptions are being thrown (Ctrl+C to terminate the DTrace gives you the statistics). Then iterate from there (try to dump the args, see if you can identify std::overflow, filter for that by adding a /arg0 == .../ or similar to the probe).

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