`brew upgrade` hangs on El Capitan

Question

I can't run brew upgrade without it hanging indefinitely. I'm using El Capitan OS. Here's the input/output:

>>$ brew upgrade
Updating Homebrew...
==> Auto-updated Homebrew!
Updated 2 taps (homebrew/core, homebrew/science).
==> Updated Formulae
artifactory         dovecot             node@4              scamper
chromedriver        node-build          openvpn
==> Deleted Formulae
pdksh

==> Upgrading 10 outdated packages, with result:
gcc 6.2.0, gdbm 1.12, libtiff 4.0.7, openssl 1.0.2j, pkg-config 0.29.1_2, python 2.7.12_2, homebrew/science/r 3.3.2, readline 7.0.1, sqlite 3.15.2, yara 3.5.0_1
==> Upgrading gcc
Warning: Building gcc from source:
  The bottle needs the Xcode CLT to be installed.
==> Using the sandbox
==> Downloading https://ftpmirror.gnu.org/gcc/gcc-6.2.0/gcc-6.2.0.tar.bz2
Already downloaded: /Users/r8t/Library/Caches/Homebrew/gcc-6.2.0.tar.bz2
==> Downloading https://raw.githubusercontent.com/Homebrew/formula-patches/e9e0e
Already downloaded: /Users/r8t/Library/Caches/Homebrew/gcc--patch-863957f90a934ee8f89707980473769cff47ca0663c3906992da6afb242fb220.patch
==> Patching
==> Applying 6.1.0-jit.patch
patching file gcc/jit/Make-lang.in
==> ../configure --build=x86_64-apple-darwin15.6.0 --prefix=/usr/local/Cellar/gc
==> make bootstrap

And then nothing.

Answer 1

It could be downloading something large and taking a long time. Try running the following so you can see the download progress:

brew update --debug --verbose