feat: add cpptrace for better stack traces by kdrienCG · Pull Request #4042 · GEOS-DEV/GEOS

kdrienCG · 2026-04-28T13:49:25Z

_{(Requires TPL PR #347)}

This PR aims to improve the stack trace output when an error is thrown.

When GEOS crashes from a C++ exception, the stack trace we log is not really useful: it points at main.cpp instead of the code that actually threw, missing on valuable informations for devs. This is not a bug in the error handler, it is how the C++ runtime works.
cpptrace solves this by providing a mechanism to get stack traces from thrown exceptions, that will make us able to know exactly where the code went.

Here is an example defining a myThrowingFunction() incorrectly using a map directly (written in the main.cpp for convenience)

Without cpptrace:

***** Exception
***** Rank 0
***** Message :
map::at

***** StackTrace of 7 frames
  - Frame  0:  geos::ErrorLogger::initCurrentExceptionMessage(geos::MsgType, std::basic_string_view<char, std::char_traits<char> >, int) 
  - Frame  1:  main /somewhere/in/my/disk/geos/GEOS/src/main/main.cpp:272 (discriminator 3)
  - Frame  2:  __libc_start_main 
  - Frame  3:  _start 
  - Frame  4:  main /somewhere/in/my/disk/geos/GEOS/src/main/main.cpp:275 (discriminator 2)
  - Frame  5:  __libc_start_main 
  - Frame  6:  _start 
*****

With cpptrace:
(truncated to fit the PR description)

***** Exception
***** Rank 0
***** Message :
map::at

***** StackTrace of 15 frames
  - Frame  0: at libstdc++.so.6
  - Frame  1: in __gxx_personality_v0 at libstdc++.so.6
  - Frame  2: at libstdc++.so.6
  - Frame  3: in std::map<std::string, int, std::less<std::string>>::at(std::string const&) at stl_map.h:551:24
  - Frame  4: in myThrowingFunction() at main.cpp:40:24
  - Frame  5: in operator() at main.cpp:49:16
  - Frame  6: in do_try_catch<const geos::NotAnError&, main(int, char**)::<lambda()>&, main(int, char**)::<lambda...
  - Frame  7: in operator() at from_current.hpp:143:32
  - Frame  8: in operator() at from_current.hpp:143:32
  - Frame  9: in operator() at from_current.hpp:143:32
  - Frame 10: in try_catch_impl<main(int, char**)::<lambda()>&, main(int, char**)::<lambda(const geos::NotAnError...
  - Frame 11: in try_catch<main(int, char**)::<lambda()>&, main(int, char**)::<lambda(const geos::NotAnError&)>&...
  - Frame 12: in main at main.cpp:129:22
  - Frame 13: in __libc_start_main at libc.so.6
  - Frame 14: in _start at geosx
*****

We have a detailled stack trace with the name of the function that throws and the correct line and character position.

rrsettgast · 2026-05-05T17:19:48Z

@kdrienCG Is there a discussion somewhere about whether we want to add this dependency?

herve-gross · 2026-05-06T16:02:15Z

@rrsettgast yes, we discussed this internally. There is value in having this TPL for debugging deeper issues. We can talk if you wish.

rrsettgast · 2026-05-06T16:30:56Z

@rrsettgast yes, we discussed this internally. There is value in having this TPL for debugging deeper issues. We can talk if you wish.

@herve-gross That decision being made without consulting others on the core team is inappropriate. The inclusion of this package covers the fundamental problem in the approach to c++ exceptions in an HPC simulation code. There are simpler solutions...like output stack on the throw.

jafranc · 2026-05-07T08:39:56Z

  while( std::getline( iss, stackLine ) )
  {
-    if( std::regex_search( stackLine, pattern ))
+    std::smatch m;
+    if( std::regex_search( stackLine, m, lvArrayPattern ) ||
+        std::regex_search( stackLine, m, cpptracePattern ) )
    {
      m_errorMsg.m_isValidStackTrace = true;
-      index = stackLine.find( ':' );
-      m_errorMsg.m_sourceCallStack.push_back( stackLine.substr( index + 1 ) );
+      m_errorMsg.m_sourceCallStack.push_back( stackLine.substr( m.position() + m.length() ) );


Suggested change

while( std::getline( iss, stackLine ) )

{

if( std::regex_search( stackLine, pattern ))

std::smatch m;

if( std::regex_search( stackLine, m, lvArrayPattern ) ||

std::regex_search( stackLine, m, cpptracePattern ) )

{

m_errorMsg.m_isValidStackTrace = true;

index = stackLine.find( ':' );

m_errorMsg.m_sourceCallStack.push_back( stackLine.substr( index + 1 ) );

m_errorMsg.m_sourceCallStack.push_back( stackLine.substr( m.position() + m.length() ) );

while( std::getline( iss, stackLine ) )

{

std::smatch m;

if( std::regex_search( stackLine, m, lvArrayPattern ) ||

std::regex_search( stackLine, m, cpptracePattern ) )

{

m_errorMsg.m_isValidStackTrace = true;

m_errorMsg.m_sourceCallStack.push_back( m.suffix().str() );

}

}

To be tested but might be interesting to leverage std::smatch to its max

Modified in commit e4334c2

jafranc · 2026-05-07T08:45:26Z

+   * @note Not signal-safe. Use signalSafeStackTrace() from inside a signal handler.
+   */
+  static std::string stackTrace();
+


Suggested change

/**

* @brief Get a stack trace from a context where signal-safety is required.

* @return The stack trace as a string.

* @note If signal-safe is required, revert back to LvArray::system

*/

I think it is worth documenting here that behavior for signal-safe is dropping cpptrace

Added in commit 5cec03

jafranc · 2026-05-07T08:56:21Z

-  catch( geos::Exception & e )
+  };
+
+  auto onGeosException = [&]( geos::Exception & e )
  { // GEOS generated exceptions management
+#ifdef GEOS_USE_CPPTRACE
+    std::string const stacktrace = StackTrace::formatStackTrace( cpptrace::from_current_exception() );


Looks like the MACRO dispach will occur at each new lambda-exception. Maybe worth passing a callback through the lambda's interface and dispatch all below ? In case we add more of this and the duplication spread

jafranc · 2026-05-07T09:01:30Z

 int main( int argc, char *argv[] )
 {
-  try
+  auto runMain = [&]


[] or [&] ?

[&] to capture argc and argv[]

kdrienCG added 5 commits April 28, 2026 10:30

add cpptrace

5881085

modify main to use cpptrace stacktrace

6a684f2

fix typo in include

69ba20e

add missing parenthesis

39051fa

reorganize main.cpp for readability

8abfda8

kdrienCG self-assigned this Apr 28, 2026

kdrienCG added type: feature New feature or request flag: requires updated TPL(s) Needs a specific TPL PR labels Apr 28, 2026

kdrienCG added 7 commits May 5, 2026 16:41

use cpptrace for GeosException

a02d863

add cpptrace in buildGuide

2977086

fix default in BuildProcess

473d53a

fix regex

5a981de

add signal-safe stack trace method

0f9d202

modify types

e88e821

move include position

197c7ee

kdrienCG marked this pull request as ready for review May 5, 2026 16:50

kdrienCG requested review from MelReyCG, OmarDuran, castelletto1, corbett5, dkachuma, herve-gross, jhuang2601, rrsettgast and wrtobin as code owners May 5, 2026 16:50

kdrienCG marked this pull request as draft May 6, 2026 09:31

herve-gross requested review from bd713 and jafranc May 6, 2026 16:14

jafranc approved these changes May 7, 2026

View reviewed changes

kdrienCG added 3 commits May 7, 2026 14:36

document signalSafeStackTrace() reverting to LvArray

5cec03f

use match_results::suffix instead of pos + len

e4334c2

remove unused exception parameter

1566e6e

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feat: add cpptrace for better stack traces #4042

feat: add cpptrace for better stack traces #4042
kdrienCG wants to merge 15 commits intodevelopfrom
feature/kdrienCG/betterStackTrace

kdrienCG commented Apr 28, 2026 •

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+  /**
+   * @brief Get a stack trace from a context where signal-safety is required.
+   * @return The stack trace as a string.
+   * @note If signal-safe is required, revert back to LvArray::system
+   */

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kdrienCG commented Apr 28, 2026 •

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rrsettgast commented May 6, 2026 •

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