That’s normal for languages like Python. The code that is actually running in Python is slow, but library functions are fast, because they are written in C.
Andy > On Jul 7, 2017, at 4:51 AM, jeff.templon.nik...@gmail.com wrote: > > Hi > > Exploring Go, 1st project is to port over my favourite playground (prime > number factorisation) from Python to Go. > > Aside: I was a big Oberon-2 fan back in the day, so I'm pretty excited about > Go making possible what never was in Oberon. > > Back to business: I was disappointed that Go is only a factor of 3 or so > faster than Python. The numbers I'm dealing with are big enough that they > don't fit into a uint64 so I'm using math/big ... turns out that about 70% of > the runtime is spent in the Mod function of math/big, and mostly this is > inside the underlying function divLarge. See profile info below. > > The naive explanation would be that Mod in Go math/big is about just as fast > as the % primitive in python (Python has big integers automatically where > needed) but the rest of the program is a factor of 10 or so faster in Go than > Python. I wonder though, especially if there is a better way to take a Mod. > The numbers are not THAT large (less than 100 decimal digits in most cases) > ... > > (pprof) top10 -cum > 13.01s of 41.11s total (31.65%) > Dropped 86 nodes (cum <= 0.21s) > Showing top 10 nodes out of 74 (cum >= 6.66s) > flat flat% sum% cum cum% > 0 0% 0% 40.45s 98.39% runtime.goexit > 0 0% 0% 40.20s 97.79% main.main > 0 0% 0% 40.20s 97.79% runtime.main > 0.28s 0.68% 0.68% 40.19s 97.76% > _/Users/templon/gofact/factoring.Mybrent > 0 0% 0.68% 40.19s 97.76% > _/Users/templon/gofact/factoring.Trial_n_X > 0.44s 1.07% 1.75% 29.42s 71.56% math/big.(*Int).Mod > 0.77s 1.87% 3.62% 28.98s 70.49% math/big.(*Int).QuoRem > 0.51s 1.24% 4.86% 28.18s 68.55% math/big.nat.div > 10.39s 25.27% 30.14% 27.47s 66.82% math/big.nat.divLarge > 0.62s 1.51% 31.65% 6.66s 16.20% runtime.makeslice > > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com > <mailto:golang-nuts+unsubscr...@googlegroups.com>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
