[Boost-users] [boost-TLS] Thread Local Storage (TLS) Question

Subject: [Boost-users] [boost-TLS] Thread Local Storage (TLS) Question
From: Kyle Ketterer (reminisc3_at_[hidden])
Date: 2013-11-24 11:16:59

Hello,

I am using multiple threads for I/O operations. The issue I am having is
joining these threads on the main thread. It appears that calling join() on
a thread with TLS pointers, it results in a hang.

I have multiple thread specific pointers declared outside of the function
and in the beginning of the method I call reset ( new std::string ) ....etc
etc. I also am acquiring some resource handlers as Im using a
boost::thread_specific_ptr < ifstream > infile

So, when I create the thread in the main thread and join() it I get a hang.
The only thing I can think of is that the handlers are not being released
so join() waits indefinitely.

I read in the documentation that the pointers should be cleaned up on
thread exit - but the thread apparently never exits because then resources
are not released? I understand that it may not be "conventional" to use a
tls pointer for ifstream but I find it a lot better than locking with
mutexes.

Also, I'm not sure if there are limits as to how many TLS pointers you can
actually use but I am currently using about 10 for one thread method.

Another thing to note is that when calling detach() on the thread, all of
the threads execute properly and I get expected output. However, I need to
call join() every x amount of threads due to OS limitations of how many
threads can actually be created. I need to read about 5000 files so
obviously I can't create 5000 threads as Windows maxes out at 700 I
believe. I am reading files off of a RAID setup so I believe this is a
situation that can benefit from multiple threads reading files.

Basically, I only want to create 4 threads at a time, then join() the
previous 4, ensure that they have all completed successfully and continue
to create more.

Any suggestions or comments on this issue?

Thanks

-- 
Kyle Ketterer
<reminisc3_at_[hidden]>