[External] : Re: jstack, profilers and other tools

[Daniel Avery]

Maybe this is not helpful, but it is how I understood the JEP


This is Little’s Law:


L = λW


Where

- L is the average number of requests being processed by a stationary
system (aka concurrency)

- λ is the average arrival rate of requests (aka throughput)

- W is the average time to process a request (aka latency)


This is a thread-per-request system:


T = L


Where

- T is the average number of threads

- L is the average number of requests (same L as in Little’s Law)


Therefore,


T = L = λW

T = λW


Prior to loom, memory footprint of (platform) threads gives a bound on
thread count:


T <= ~1000


After loom, reduced memory footprint of (virtual) threads gives a relaxed
bound on thread count:


T <= ~1000000


Relating thread count to Little’s Law tells us that virtual threads can
support a higher average arrival rate of requests (throughput), or a higher
average time to process a request (latency), than platform threads could:


T = λW <= ~1000000
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