堆栈溢出后如何在 OCaml 中获得完整的、未处理的堆栈跟踪？

Question

堆栈溢出的 OCaml 堆栈跟踪被截断；例如，以下程序生成如下所示的堆栈跟踪：

let rec f0 () = 1 + f1 ()
    and f1 () = 1 + f2 ()
    and f2 () = 1 + f3 ()
    and f3 () = 1 + f4 ()
    and f4 () = 1 + f5 ()
    and f5 () = 1 + f5 ()

let _ =
  Printexc.record_backtrace true;
  f0 ()

Fatal error: exception Stack overflow
Raised by primitive operation at file "Whosebug.ml", line 6, characters 20-25
Called from file "Whosebug.ml", line 6, characters 20-25
…
Called from file "Whosebug.ml", line 6, characters 20-25

当错误不是堆栈溢出时与堆栈跟踪对比（将最后的f5 ()更改为failwith "Oops":

Fatal error: exception Failure("Oops")
Raised at file "pervasives.ml", line 30, characters 22-33
Called from file "Whosebug.ml", line 6, characters 20-35
Called from file "Whosebug.ml", line 5, characters 20-25
Called from file "Whosebug.ml", line 4, characters 20-25
Called from file "Whosebug.ml", line 3, characters 20-25
Called from file "Whosebug.ml", line 2, characters 20-25
Called from file "Whosebug.ml", line 1, characters 20-25
Called from file "Whosebug.ml", line 10, characters 2-7

如何防止 OCaml 截断堆栈跟踪？

Answer 1

当我重现你的结果时，我得到了 1024 行回溯，这是一个可疑的数字。

事实上，我看到该库在 byterun/caml/backtrace_prim.h:

中强加了 1024 的硬编码最大回溯大小

#define BACKTRACE_BUFFER_SIZE 1024

如果您想要更大的回溯，您可能必须构建一个新的标准库。

对于它的价值，我用 ocamlc 做了一点测试，当发生溢出时，我看到大约 262,000 个活动堆栈帧（使用默认堆栈大小）。

（使用 OCaml 4.04 的正确文件名进行编辑。）

Answer 2

您可以限制堆栈，使其不会溢出回溯缓冲区，例如（使用字节码测试）

$ env OCAMLRUNPARAM=b,l=1000 ./test
[...]
Called from file "test.ml", line 6, characters 20-25
Called from file "test.ml", line 6, characters 20-25
Called from file "test.ml", line 5, characters 20-25
Called from file "test.ml", line 4, characters 20-25
Called from file "test.ml", line 3, characters 20-25
Called from file "test.ml", line 2, characters 20-25
Called from file "test.ml", line 1, characters 20-25
Called from file "test.ml", line 10, characters 2-7

Answer 3

您可以使用 ocamldebug 获取堆栈跟踪：

ocamlc Whosebug.ml -o Whosebug
ocamldebug Whosebug

然后在 ocamldebug 中：

(ocd) run
 [...] 
 Uncaught exception: Stack_overflow
(ocd) backstep
(ocd) bt

您可能希望将调试标志添加到 ocamlc (-g) 以在调试器中执行额外操作。

堆栈溢出后如何在 OCaml 中获得完整的、未处理的堆栈跟踪？

How can I get a complete, untrucated stack trace in OCaml after a stack overflow?

stack-overflow

debugging

ocaml