It depends upon following factors:
<ol>
<li>CPU cores</li>
<li>CPU bound task</li>
<li>I/O bound tasks</li>
</ol>
General formula is
No. of threads(t) = No. of cores(c) (1+ wait time/CPU time)
 = No. of cores (1+ blocking co-efficient)
wait time: How much time a thread takes for one task/s I/O operations to complete.
blocking coefficient can be 0 to 1
for CPU bound task: 
t = c * (1+ 0/cpu time) = no. of cores ( since CPU will be utilized fully even with one thread, hence CPU will not be idle, hence no context switching occurs)
for I/O bound task:
t = c * (1+ &gt;0)

It depends upon following factors:
1. CPU cores
2. CPU bound task
3. I/O bound tasks

General formula is
No. of threads(t) = No. of cores(c) * (1+ wait time/CPU time)
                         = No. of cores * (1+ blocking co-efficient)

wait time: How much time a thread takes for one task/s I/O operations to complete.
blocking coefficient can be 0 to 1

for CPU bound task: 
t = c * (1+ 0/cpu time) = no. of cores ( since CPU will be utilized fully even with one thread, hence CPU will not be idle, hence no context switching occurs)

for I/O bound task:
t = c * (1+ >0) 


How to determine no. of threads in thread pool ?

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