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====== C - C++ Threads - Troubleshooting - Over-subscription ======

Over-subscription is a situation where more threads are vying for runtime than the underlying hardware can support.

One of the biggest cost associated with multiple threads is that of context-switches that happens when the processor switches threads.

Ideally, the you'd not want to create more threads than the hardware can support.

----

===== Avoid Over-subscription when working with multiple threads =====

Obtain the number of threads that can be run in parallel from an application.

Often this might coincide with the number of logical cores, but not always.

<code cpp>
#include <thread>
#include <iostream>

int main(int argc, char **argv)
{
  unsigned int max_threads = std::thread::hardware_concurrency();

  std::cout << "MAX Threads=" << max_threads << std::endl;

   return 0;
}
</code>

returns:

<code>
MAX Threads=24
</code>

<WRAP info>
**NOTE:**  This means that no more than 24 threads should be forked.
</WRAP>