d8e19cd79a
This adds a P/V style semaphore mechanism to the resource graph. This enables the user to specify a number of "id:count" tags associated with each resource which will reduce the parallelism of the CheckApply operation to that maximum count. This is particularly interesting because (assuming I'm not mistaken) the implementation is dead-lock free assuming that no individual resource permanently ever blocks during execution! I don't have a formal proof of this, but I was able to convince myself on paper that it was the case. An actual proof that N P/V counting semaphores in a DAG won't ever dead-lock would be particularly welcome! Hint: the trick is to acquire them in alphabetical order while respecting the DAG flow. Disclaimer, this assumes that the lock count is always > 0 of course.
9 lines
313 B
Bash
Executable File
9 lines
313 B
Bash
Executable File
#!/bin/bash -e
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# should take at least 55s, but fail if we block this
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# TODO: it would be nice to make sure this test doesn't exit too early!
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$timeout --kill-after=120s 110s ./mgmt run --yaml sema-1.yaml --sema 2 --converged-timeout=5 --no-watch --no-pgp --tmp-prefix &
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pid=$!
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wait $pid # get exit status
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exit $?
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