Setting
xxx-jobset-repeats = patchelf:master:2
will cause Hydra to perform every build step in the specified jobset 2
additional times (i.e. 3 times in total). Non-determinism is not fatal
unless the derivation has the attribute "isDeterministic = true"; we
just note the lack of determinism in the Hydra database. This will
allow us to get stats about the (lack of) reproducibility of all of
Nixpkgs.
Builds can now specify the attribute "isDeterministic = true" to tell
Hydra to build with build-repeat > 0. If there is a mismatch between
rounds, the step / build fails with a suitable status.
Maybe this should be a meta attribute, but that makes it invisible to
hydra-queue-runner, and it seems reasonable to make a claim of
mandatory determinism part of the derivation (since e.g. enabling this
flag should trigger a rebuild).
We now take into account the memory necessary for compressing the NAR
being exported to the binary cache, plus xz compression overhead.
Also, we now release the memory tokens for the NAR accessor *after*
releasing the NAR accessor. Previously the memory for the NAR accessor
might still be in use while another thread does an allocation, causing
the maximum to be exceeded temporarily.
Also, use notify_all instead of notify_one to wake up memory token
waiters. This is not very nice, but not every waiter is requesting the
same number of tokens, so some might be able to proceed.
If a step is cancelled just as its builder step is starting,
doBuildStep() will return sRetry. This causes builder() to make the
step runnable again, since the queue monitor may have added new builds
referencing it. The idea is that if the latter condition is not true,
the step's reference count will drop to zero and it will be
deleted. However, if the dispatcher thread sees and locks the step
before the reference count can drop to zero in the builder thread, the
dispatcher thread will start a new builder thread for the step. Thus
the step can be kept alive for an indefinite amount of time.
The fix is for State::builder() to use a weak pointer to the step, to
ensure that the step's reference count can drop to zero *before* it's
added to the runnable queue.
This was a bad idea because pthread_cancel() is unsalvageable broken
in C++. Destructors are not allowed to throw exceptions (especially in
C++11), but pthread_cancel() can cause a __cxxabiv1::__forced_unwind
exception inside any destructor that invokes a cancellation
point. (This exception can be caught but *must* be rethrown.) So let's
just kill the builder process instead.
It was hitting
assert(reservation.unique());
Since we do want the machine reservation to be released before calling
wakeDispatcher(), let's use a different object for keeping track of
active steps.
We now kill active build steps when there are no more referring
builds. This is useful e.g. for preventing cancelled multi-hour TPC-H
benchmark runs from hogging build machines.
