threads/2149: thread_db_get_info: cannot get thread info: generic error on fork()/execvp()

[alex@alex.org.uk]

>Number:         2149
>Category:       threads
>Synopsis:       thread_db_get_info: cannot get thread info: generic error on fork()/execvp()
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    unassigned
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 18 12:48:01 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     alex@alex.org.uk
>Release:        GNU gdb 6.4-debian
>Organization:
>Environment:
Ubuntu Dapper, stock gdb, stock C compiler, stock libraries
Linux polonius 2.6.15-26-amd64-generic #1 SMP PREEMPT Mon Jul 17 19:50:04 UTC 2006 x86_64 GNU/Linux
gcc (GCC) 4.0.3 (Ubuntu 4.0.3-1ubuntu5)
GNU gdb 6.4-debian
>Description:
On certain calls to fork(), execvp(), gdb does the following:
  thread_db_get_info: cannot get thread info: generic error
after that it is unusable.

This is difficult to replicate in the general case, though I have seen it happen several times with the wxWidgets library using the ::wxExecute() function. I have finally got it 100% repeatable (of course, on the function I want to debug...).

Sadly it is /not/ repeatable using the minimal wxWidgets sample application for exec.
>How-To-Repeat:
Download sources to Xara LX (see http://www.xaraxtreme.org/). You will need at least revision r1463. Build a debug version. Run it under gdb. Draw any shape. File->Export. Browse for other folders, select "MIFF File". Chose any file name ending in ".miff" and OK the default options.

At imgmgkft.cpp line 1313 it calls ::wxExecute to run "convert" (ImageMagick). This does a fork() and an execvp(). 100% reliably, gdb suffers the above internal error.

I don't believe there is anything special about ImageMagick - I've seen similar things happen using the print setup dialog (which runs lp commands), but not reliably.
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: