some data are shared with some cores. • If a core updates the shared data, • Then it notifies other cores, and they stop processing. • It causes slow down. • If there are many cores, waiting time grows exponentially. • Elixir is immutable, that is, it forbids all updates of shared data. • So, the other cores don’t need to stop processing. 9 © 2021 Susumu Yamazaki 4IBSFE%BUB $PSF #1 $PSF2 3.14 4IBSFE%BUB $PSF #1 $PSF2 3.14 →1.5 6QEBUF /PUJGZ 4UPQ1SPDFTTJOH 4IBSFE%BUB $PSF #1 $PSF2 3.14 %PO`U 6QEBUF %PO`UOFFEUP TUPQQSPDFTTJOH