num_cpus::get() == 18446744073709551615

[oh-its-jimjam]

num_cpus::get() is totally broken (or my Macbook Air has surpassed the axioms of physics and now has 18,446,744,073,709,551,615 cores).

This is braking a lot of APIs so please treat this as urgent!

I spotted it as I am using nickel.rs and my server wouldn't start and debugged it to find out that Hyper was throwing an arithmetic overflow at server/mod.rs:90 and it's due to a broken num_cpus::get()

[zr40]

18446744073709551615 is a 64 bit unsigned integer with all bits set. I suspect it's a -1 signed integer being interpreted as unsigned.

[oh-its-jimjam]

Ok, I fixed it. It is due to wrong value to libc::sysconf as the hardcoded value of 84 is incorrect for Mac OS X; it should be 58.

[oh-its-jimjam]

Also, to fix this in the correct way, we should implement a libc::_SC_NPROCESSORS_ONLN rather than hardcoding it. I will submit a pull request to implement it and will then add another pull request to your project.

[seanmonstar]

Sorry about the breakage. I do not have a Mac, and so tried asking for help
of people trying the PR. I got one to try it and said it worked, so I
published.

libc does not yet have that const. Hence it's hard-coded and has the const
in a comment.

On Mon, Apr 13, 2015, 3:23 AM lambdaburrito notifications@github.com
wrote:

Also, to fix this in the correct way, we should add a
libc::_SC_NPROCESSORS_ONLN rather than hardcoding it.

—
Reply to this email directly or view it on GitHub
#2 (comment).

[oh-its-jimjam]

My pull request to fix is left hardcoded until libc adds it as a constant. When it's added as a constant, you won't need any specific targeted get_num_cpus() function. Once it's upstream, I will submit another pull request.

[seanmonstar]

Merged #4