Test suite fails on macOS about acid-state

[ddssff]

I wonder what the limit is on macos?

[sternenseemann]

$ launchctl limit maxfiles
	maxfiles    256            unlimited   

So seems the soft fd limit is quite low by default (256 on my system) which sounds plausible that you hit in the test suite.

[ddssff]

And yet...what changed? And why does this feel so familiar?

[sternenseemann]

I'm not sure what you are referring to. For what it's worth acid-state has been failing like this on darwin since May at least. Before that I have no data, sadly.

[ddssff]

The limit is 1024 on ubuntu, if I set ulimit -n 256 and run the test suite it fails.

[ddssff]

    ━━━ Exception (IOException) ━━━
    state/KeyValueSequentialTest/open.lock: openFd: resource exhausted (Too many open files)
  
    This failure can be reproduced by running:
    > recheck (Size 42) (Seed 16729543741219666746 3391217788386191459) prop_sequential
  
  ✗ prop_parallel failed at test/Data/Acid/StateMachineTest.hs:493:15
    after 17 tests and 5 shrinks.
  
        ┏━━ test/Data/Acid/StateMachineTest.hs ━━━
    486 ┃ acidStateParallelProperty :: AcidStateInterface s -> Gen s -> Range Int -> Range Int -> [Command Gen (TestT IO) (Model s)] -> Property
    487 ┃ acidStateParallelProperty i gen_initial_state prefix_range parallel_range commands = property $ do
    488 ┃     actions <- forAll $ Gen.parallel prefix_range parallel_range StateAbsent $
    489 ┃                  [ open i gen_initial_state
    490 ┃                  , checkpoint i
    491 ┃                  ] ++ commands ++ commands
        ┃                  │ ━━━ Prefix ━━━
        ┃                  │ 
        ┃                  │ ━━━ Branch 1 ━━━
        ┃                  │ 
        ┃                  │ ━━━ Branch 2 ━━━
        ┃                  │ Var 0 = Open (KeyValue (fromList []))
    492 ┃     test $ do liftIO $ resetState i
    493 ┃               executeParallel StateAbsent actions
        ┃               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        ┃               │ ━━━ Exception (IOException) ━━━
        ┃               │ state/KeyValueParallelTest: getDirectoryContents:openDirStream: resource exhausted (Too many open files)
  
    This failure can be reproduced by running:
    > recheck (Size 16) (Seed 5671783275542411754 2683756560449981757) prop_parallel

[stepcut]

I think the problem is that in this function,

https://github.com/acid-state/acid-state/blob/master/test/Data/Acid/StateMachineTest.hs#L486

it calls 'open' to open an acid-state test DB, but never calls close. So there is a file handle leak and that exceeds the limits on OS X. However, the way the 'parallel' function works in Hedgehog -- you can provide a prefix list of commands, but not a postfix list of commands. So it is not obvious how to close the handles.

Since this is just a test suite, the file handle leaks are perhaps ok, aside from the failure on OS X. Perhaps there is a way to limit the number of tests run to avoid hitting the limit on OS X?

[ddssff]

Increasing the limit on macos might be the easy thing.