This hang for some reason didn't trigger in the Nix build, but did
running 'make installcheck' interactively. What happened:
* Store::addMultipleToStore() calls a SinkToSource object to copy a
path, which in turn calls LegacySSHStore::narFromPath(), which
acquires a connection.
* The SinkToSource object is not destroyed after the last bytes has
been read, so the coroutine's stack is still alive and its
destructors are not run. So the connection is not released.
* Then when the next path is copied, because max-connections = 1,
LegacySSHStore::narFromPath() hangs forever waiting for a connection
to be released.
The fix is to make sure that the source object is destroyed when we're
done with it.
RewritingSink can handle being fed input where a reference crosses a
chunk boundary. we don't need to load the whole source into memory, and
in fact *not* loading the whole source lets nix build FODs that do not
fit into memory (eg fetchurl'ing data files larger than system memory).
Some activities are numerous but usually very short (e.g. copying a
source file to the store) which would cause a lot of flickering. So
only show activities that have been running for at least 10 ms.
Rather than directly copying the source to its dest, copy it first to a
temporary location, and eventually move that temporary.
That way, the move is at least atomic from the point-of-view of the destination
The recursive copy from the stl doesn’t exactly do what we need because
1. It doesn’t delete things as we go
2. It doesn’t keep the mtime, which change the nars
So re-implement it ourselves. A bit dull, but that way we have what we want
In `nix::rename`, if the call to `rename` fails with `EXDEV` (failure
because the source and the destination are in a different filesystems)
switch to copying and removing the source.
To avoid having to re-implement the copy manually, I switched the
function to use the c++17 `filesystem` library (which has a `copy`
function that should do what we want).
Fix#6262
Once a derivation goal has been completed, we check whether or not
this goal was meant to be repeated to check its output.
An early return branch was preventing the worker to reach that repeat
code branch, hence breaking the --check command (#2619).
It seems like this early return branch is an artifact of a passed
refactoring. As far as I can tell, buildDone's main branch also
cleanup the tmp directory before returning.
By default, Nix sets the "cores" setting to the number of CPUs which are
physically present on the machine. If cgroups are used to limit the CPU
and memory consumption of a large Nix build, the OOM killer may be
invoked.
For example, consider a GitLab CI pipeline which builds a large software
package. The GitLab runner spawns a container whose CPU is limited to 4
cores and whose memory is limited to 16 GiB. If the underlying machine
has 64 cores, Nix will invoke the build with -j64. In many cases, that
level of parallelism will invoke the OOM killer and the build will
completely fail.
This change sets the default value of "cores" to be
ceil(cpu_quota / cpu_period), with a fallback to
std:🧵:hardware_concurrency() if cgroups v2 is not detected.
The workaround for "Some distros patch Linux" mentioned in
local-derivation-goal.cc will not help in the `--option
sandbox-fallback false` case. To provide the user more helpful
guidance on how to get the sandbox working, let's check to see if the
`/proc` node created by the aforementioned patch is present and
configured in a way that will cause us problems. If so, give the user
a suggestion for how to troubleshoot the problem.
local-derivation-goal.cc contains a comment stating that "Some distros
patch Linux to not allow unprivileged user namespaces." Let's give a
pointer to a common version of this patch for those who want more
details about this failure mode.
