Re: g++ 4.7 with g++0x threads & profiling

[Sam Varshavchik <mrsam at courier-mta dot com>]

Folkert van Heusden writes:

> Hi,
>
> I have a C++ application using the new std::thread functionality.
> At random I see all kinds of crashes, mostly in std::string but also
> in std::map and friends.
> I have profiling (-pg) enabled. It seems that if I disable profiling,
> also the random errors (SIGSEGV) disappear.
> Are there any known issues with profiling, c++0x and gcc version 4.7
> with this? (tried g++ 4.6 as well)

Neither std::map, nor std::string, is thread-safe, AFAIK. Individual  
instances of these, and pretty much all other classes, must be appropriately  
protected and accessed in a safe thread context, using std::mutex or a  
reasonable facsimile. You have not mentioned whether or not you may be  
potentially accessing same instances of std::string or std::map from  
concurrent threads, and whether you're employing std::mutex to do so.

Profiling modifies runtime behavior, by its inherent nature. If there's ill- 
formed, non-deterministic behavior, such as thread-unsafe access; it would  
not be unusual for this to manifest itself with more or less frequency,  
either in presence or in the absence of, runtime profiling.

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