Re: [Boost-users] Does boost::thread_group::create_thread have memory leak?

From: pete_at_[hidden]
Date: 2007-01-20 23:14:06

On Sat, Jan 20, 2007 at 01:02:56PM +0100, Roland Schwarz wrote:
> pete_at_[hidden] wrote:
> >It appears to come from this line in boost/lib/src/pthread.cpp:
> I suspect you mean file: boost/libs/thread/src/thread.cpp.

Doh! Sorry, you are correct.

> >Could it be that the leak is being created by using the tmp object in
> >the thread creation?  I've read advise about NOT doing that?
> 
> I am not sure if I understand you correctly. Could you please try to be 
> more explicit?
> 
> Which tmp object are you refering to?
> Where did you read what?

Sorry again, as I was not correct when I said that.  I spoke before I should
have.

I was not paying attention to the auto_ptr, it is not a tmp.

However, It looks like thread_group::create_thread is really just calling pthread_create in my case. ie., Linux OS.   

Is is possible that this could be an issue with new/delete vs malloc/free?

I'm pretty sure that pthread_create uses malloc, and on line 331 thread_group::~thread_group there is a delete taking place for all those pointers.

    thread_group::~thread_group()
    {
        // We shouldn't have to scoped_lock here, since referencing this object
        // from another thread while we're deleting it in the current thread is
        // going to lead to undefined behavior any way.
        for (std::list<thread*>::iterator it = m_threads.begin();
            it != m_threads.end(); ++it)
        {
            delete (*it);
        }
    }

I'm still relatively new to c++ and even newer to boost, so maybe I'm way off.  However, I'm mentioning it because it seems to raise a flag with Effective C++'s recommendation.  

Also, I don't think even free'ing a joined pthread is necessary in
the first place, so I'm kinda confused about what's going on here
or what the effect might be.

Any other ideas?

Thanks,

Pete

> 
> I guess your original sample exhibits the leak?
> 
> I'll try to reproduce locally:
> In order to get equivalent test conditions, could you post the exact 
> steps you used to create and invoke the test?
> 
> >
> >I realized after reading your email again that 1.34 is what you
> >specified, but I used 1.35.  Would that be a problem?
> 
> No I don't expect so. They should currently be the same.
> 
> Roland
> 

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