What’s the biggest advantage of implementing thread in user space? What’s the biggest disadvantage?

The biggest advantage of implementing threads in user space is that it can be done without the involvement of the operating system kernel, which is a complex and time-consuming task. This can result in faster thread creation and switching times, as well as reduced overhead and improved performance.

However, the biggest disadvantage of implementing threads in user space is that they lack the ability to take advantage of certain kernel-level optimizations, such as kernel-level scheduling and synchronization primitives. This can result in decreased performance when dealing with heavily contended resources or when a thread blocks while waiting for I/O. Additionally, user-level threads may not be able to take advantage of multiple processors or cores in a system, which can limit their scalability.