Thread Pool vs Thread Spawning

Question

Can someone list some comparison points between Thread Spawning vs Thread Pooling, which one is better? Please consider the .NET framework as a reference implementation tha

Answer 1

A "pool" contains a list of available "threads" ready to be used whereas "spawning" refers to actually creating a new thread.

The usefulness of "Thread Pooling" lies in "lower time-to-use": creation time overhead is avoided.

In terms of "which one is better": it depends. If the creation-time overhead is a problem use Thread-pooling. This is a common problem in environments where lots of "short-lived tasks" need to be performed.

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As pointed out by other folks, there is a "management overhead" for Thread-Pooling: this is minimal if properly implemented. E.g. limiting the number of threads in the pool is trivial.

Answer 2

The main difference is that a ThreadPool maintains a set of threads that are already spun-up and available for use, because starting a new thread can be expensive processor-wise.

Note however that even a ThreadPool needs to "spawn" threads... it usually depends on workload - if there is a lot of work to be done, a good threadpool will spin up new threads to handle the load based on configuration and system resources.

Answer 3

This answer is a good summary but just in case, here is the link to Wikipedia:

http://en.wikipedia.org/wiki/Thread_pool_pattern

Answer 4

Thread pool threads are much cheaper than a regular Thread, they pool the system resources required for threads. But they have a number of limitations that may make them unfit:

• You cannot abort a threadpool thread
• There is no easy way to detect that a threadpool completed, no Thread.Join()
• There is no easy way to marshal exceptions from a threadpool thread
• You cannot display any kind of UI on a threadpool thread beyond a message box
• A threadpool thread should not run longer than a few seconds
• A threadpool thread should not block for a long time

The latter two constraints are a side-effect of the threadpool scheduler, it tries to limit the number of active threads to the number of cores your CPU has available. This can cause long delays if you schedule many long running threads that block often.

Many other threadpool implementations have similar constraints, give or take.

Answer 5

It depends on what you want to execute on the other thread.

For short task it is better to use a thread pool, for long task it may be better to spawn a new thread as it could starve the thread pool for other tasks.

Answer 6

My feeling is that you should start just by creating a thread as needed... If the performance of this is OK, then you're done. If at some point, you detect that you need lower latency around thread creation you can generally drop in a thread pool without breaking anything...