To be concrete about this, http://canonical.org/~kragen/sw/dev3/forkovh.c took 670μs to fork, exit, and wait on the first laptop I tried it on, but only 130μs compiled with dietlibc instead of glibc, and with glibc on a 2.3 GHz E5-2697 Xeon, it took 130μs compiled with glibc.
httpdito http://canonical.org/~kragen/sw/dev3/server.s (which launches a process per request) seems to take only about 50μs because it's not linked with any C library and therefore only maps 5 pages. Also, that doesn't include the time for exit() because it runs multiple concurrent child processes.
On this laptop, a Ryzen 5 3500U running at 2.9GHz, forkovh takes about 330μs built with glibc and about 130–140μs built with dietlibc, and `time python3 -c True` takes about 30000–50000μs.
I wrote a Python version of forkovh http://canonical.org/~kragen/sw/dev3/forkovh.py and it takes about 1200μs to fork(), _exit(), and wait().
If anyone else wants to clone that repo and test their own machines, I'm interested to hear the results, especially if they aren't in Linux. `make forkovh` will compile the C version.
1200μs is pretty expensive in some contexts but not others. Certainly it's cheaper than spawning a new Python interpreter by more than an order of magnitude.
httpdito http://canonical.org/~kragen/sw/dev3/server.s (which launches a process per request) seems to take only about 50μs because it's not linked with any C library and therefore only maps 5 pages. Also, that doesn't include the time for exit() because it runs multiple concurrent child processes.
On this laptop, a Ryzen 5 3500U running at 2.9GHz, forkovh takes about 330μs built with glibc and about 130–140μs built with dietlibc, and `time python3 -c True` takes about 30000–50000μs. I wrote a Python version of forkovh http://canonical.org/~kragen/sw/dev3/forkovh.py and it takes about 1200μs to fork(), _exit(), and wait().
If anyone else wants to clone that repo and test their own machines, I'm interested to hear the results, especially if they aren't in Linux. `make forkovh` will compile the C version.
1200μs is pretty expensive in some contexts but not others. Certainly it's cheaper than spawning a new Python interpreter by more than an order of magnitude.