Re: ActiveMQ CPP library - limit on number of connections/threads

[Timothy Bish]

On 08/25/2017 06:58 PM, duncant wrote:
I did some more digging on this in the decaf code.
The error message is coming from this code in ThreadLocalImpl.cpp:

ThreadLocalImpl::ThreadLocalImpl() : tlsKey(0) {
     tlsKey = Threading::createThreadLocalSlot(this);

     if (tlsKey < 0) {
         throw RuntimeException(
             __FILE__, __LINE__, "Thread Local storage limit reached.");
     }
}

So looking at createThreadLocalSlot, in Threading.cpp I see:

     ...stuff...
     for (index = 0; index < DECAF_MAX_TLS_SLOTS; index++) {
         if (library->tlsSlots[index] == NULL) {
             library->tlsSlots[index] = threadLocal;
             break;
         }
     }
     ...stuff...
     return index < DECAF_MAX_TLS_SLOTS ? index : -1;

So, looks like DECAF_MAX_TLS_SLOTS is what's causing my problem.  This is
defined in ThreadingTypes.h:

     #define DECAF_MAX_TLS_SLOTS 384


Hmmm... 384 is 128 times 3.  So maybe each mq consumer creates 3 threads,
therefore I'm running out at 128?
I wonder what will happen if I just increase DECAF_MAX_TLS_SLOTS and
rebuild.  Right now I'm just blundering around.  I don't suppose there are
still any decaf developers around?

Increasing the slots will allow for more threadlocal storage at the cost 
of more memory overhead.
Reference -> https://issues.apache.org/jira/browse/AMQCPP-605


--
Tim Bish
twitter: @tabish121
blog: http://timbish.blogspot.com/