Memory allocation in applications that use multiple threads can be tricky. Here are some of the main challenges:

1. Race Conditions: When several threads try to use memory at the same time, it can lead to problems. This means you might get different results when you expect the same.

2. Fragmentation: When memory is used and freed repeatedly, it can leave little gaps in memory. This makes it harder to find enough space when you need it.

3. Overhead: Managing many threads at once can take up more processing power, which can slow things down during memory allocation.

Solutions:

• Mutexes/Semaphores: These are tools that help threads work together better. They can prevent race conditions by making sure that only one thread uses the memory at a time.

• Memory Pooling: This means using a set amount of memory that is already set aside, which helps to avoid gaps and makes using memory easier.

• Optimized Allocators: These are special processes that help manage memory for multiple threads in a smarter way, so it uses less power and works faster.