coptr | robust inference of microbial growth dynamics | Genomics library

First of all, std::thread::join does not kill a thread - it waits for the thread to finish.

You have 3 producer threads (each producing 100 items), but only 2 consumer threads (each consuming 100 items). This means there's a surplus of 100 items being produced. Add to that a buffer with a capacity of only 10 items, and your producers will never finish on their own before the consumers have finished.

This means you need a mechanism to end the producer loops early (ie. as soon as the consumer loops have ended).

Your attempt to address this has however left you open to a infinitely blocked thread (similar to a deadlock, but not quite). The scenario that jumps out at me (which doesn't mean that's the only one), is when one or more producer threads are blocked on cond.wait(locker); (in Buffer::put), but all consumer threads have ended (meaning the cond.notify_one(); in Buffer::get will no longer happen). Those producer thread(s) will thus wait forever, and the corresponding join(s) won't return.

To avoid this situation, you can consider using std::condition_variable::wait_for instead of std::condition_variable::wait to avoid the blocking wait. Every time the timeout happens, you have a chance to check if the consumers have ended, and end the producer thread when that's the case.

The way you check if the consumer threads have ended could also be improved. One option would be to first join the 2 consumer threads. When both consumer threads are joined, signal all producer threads that they should end as well, then join the producer threads. The signal in question could be eg. a std::atomic that is checked in each iteration of the producer. This will work best if the BufferPtr->put(); is changed to a BufferPtr->try_put();, which either inserts an item in the buffer, or returns immediately (or after a timeout if you prefer) when the buffer is full.

Note that there are more issues in your code (not least of which is that you use the same condition_variable to signal both "not empty" and "not full"), but they're not in the scope of this question.