This adds lockfile tracking to Spack's lock mechanism, so that we ensure that there
is only one open file descriptor per inode.
The `fcntl` locks that Spack uses are associated with an inode and a process.
This is convenient, because if a process exits, it releases its locks.
Unfortunately, this also means that if you close a file, *all* locks associated
with that file's inode are released, regardless of whether the process has any
other open file descriptors on it.
Because of this, we need to track open lock files so that we only close them when
a process no longer needs them. We do this by tracking each lockfile by its
inode and process id. This has several nice properties:
1. Tracking by pid ensures that, if we fork, we don't inadvertently track the parent
process's lockfiles. `fcntl` locks are not inherited across forks, so we'll
just track new lockfiles in the child.
2. Tracking by inode ensures that referencs are counted per inode, and that we don't
inadvertently close a file whose inode still has open locks.
3. Tracking by both pid and inode ensures that we only open lockfiles the minimum
number of times necessary for the locks we have.
Note: as mentioned elsewhere, these locks aren't thread safe -- they're designed to
work in Python and assume the GIL.
Tasks:
- [x] Introduce an `OpenFileTracker` class to track open file descriptors by inode.
- [x] Reference-count open file descriptors and only close them if they're no longer
needed (this avoids inadvertently releasing locks that should not be released).
Spack's source mirror was previously in a plain old S3 bucket. That will still
work, but we can do better. This switches to AWS's CloudFront CDN for hosting
the mirror.
CloudFront is 16x faster (or more) than the old bucket.
- [x] change mirror to https://mirror.spack.io
This PR fixes two problems with clang/llvm's version detection. clang's
version output looks like this:
```
clang version 11.0.0
Target: x86_64-unknown-linux-gnu
```
This caused clang's version to be misdetected as:
```
clang@11.0.0
Target:
```
This resulted in errors when trying to actually use it as a compiler.
When using `spack external find`, we couldn't determine the compiler
version, resulting in errors like this:
```
==> Warning: "llvm@11.0.0+clang+lld+lldb" has been detected on the system but will not be added to packages.yaml [reason=c compiler not found for llvm@11.0.0+clang+lld+lldb]
```
Changing the regex to only match until the end of the line fixes these
problems.
Fixes: #19473
clean_environment(): Unset three more environment variables:
MAKEFLAGS: Affects make, can eg indirectly inhibit enabling parallel build
DISPLAY: Tests of GUI widget libraries might try to connect to an X server
TERM: Could make testsuites attempt to color their output
