memcpy() creates segmentation fault after too many iterations

Question

I am trying to create a multithreading library in c. Here is the link to whole project (because pasting the code here would be too much text).

In the file tests/MultithreadingTests.c I am testing to the functionality of lib/systems/multithreading/src/ThreadPool.c. The function add_work adds any routine function the the work queue which utilises the functionality of lib/sds/lists/src/Queue.c and lib/sds/lists/src/LinkedList.c. In MultithreadingTests.c, NUM_TESTS defines the number of jobs I am adding to the work queue to be performed by NUM_THREADS

I am facing a weird issue with the code. If NUM_TESTS any number is less than 349,261, the code works perfectly fine but any number higher than or equal to 349,261 results in segmentation fault. I tried to check where exactly the segmentation fault is happening and found that it happens in the lib/sds/lists/src/Node.c at line number 29 at memcpy(node->data, data, size);

The flow of code for the error is

• tests/MultiThreadingTests.c line 95 at pool->add_work(pool, new_thread_job(routine, &arguments[i]));
• lib/systems/multithreading/src/ThreadPool.c line 150 thread_pool->work.push(&thread_pool->work, &job, sizeof(job));
• lib/sds/lists/src/Queue.c line 54 return q->list.insert(&q->list, q->list.length, data, size);
• lib/sds/lists/src/LinkedLists.c line 107 Node *node_to_insert = new_node(data, size);
• lib/sds/lists/src/Node.c line 29 memcpy(node->data, data, size);

I am not sure why this issue is happening only when the number of jobs is higher than or equal to 349,261 but not when its smaller.