Re: [boost] [test] Possible design flaw inexecution_monitor::catch_signals

From: Jim Douglas (jim_at_[hidden])
Date: 2006-03-03 02:14:14

Gennadiy Rozental wrote:
>>In brief, the primary execution failure corrupts the program heap. When
>>the C++ exception is thrown at execution_monitor:462, the exception
>>handling mechanism calls __cxa_allocate_exception which then calls
>>std::malloc. But, because of the corrupted heap, this call blocks
>>against the malloc mutex.
> 
> Is there any way to avoid memory allocation? 

Yes, don't throw an exception. It is the system that is allocating 
memory for the exception.

> The exception itself doesn't allocate the memory (namely for the reasons above). 

Oh yes it does. Before you can throw an exception you have to create one 
and that will involve a call to new, which in most cases results in a 
call to malloc.

[...]

> You could disable catching system errors for this test or this configuration 
> (using either command line argument or environment variable). 

I am trying to make a general point here that the code is badly designed 
and is prone to failure on any OS, not just QNX. To use a simple analogy 
you are currently asking a mortally wounded soldier to get back in the 
front line and continue to fight. A memory segment violation _may_ 
cripple a process. There is _no_guarantee_ that following a memory 
segment violation a process is in a fit state to continue execution. 
Don't you remember the good old days when a memory segment violation 
under Windows would wipe out the entire OS :-)

See also Ian McCulloch's post that backs me up.

BTW the specific case has been dealt with by withdrawing the test. I 
just want to make sure this does not happen again to anyone.

Jim