`OSError: too many files open` on linux

[goodboy]

It's odd because i've seen this from 2 diff sources in the #302 history but not sure either are legit.

Main source of issue seems to be that we're loading boat loads of data and one of 2 sys level calls trigger this:

• socket re-connection of some sort to the FSP engine inside the trio streams apis
• our ShmArray's usage of stdlib's SharedMemory causes it when attaching (not creating) to an existing buffer repeatedly (again something the fsp engine will do on task respawn-resyncs when a new history frame is loaded.

The next time someone sees this please put in the whole traceback. I've stuck some preventative code in #302 but it didn't seem to do much for me iirc.

Another thing we cam try for the shm case is a busy loop around the non-create call:

key = 'blah'
 shm = SharedMemory(
                name=key,
                create=True,
            )
 while True:
    shm = SharedMemory(
                name=key,
                create=False,
            )

and see if that triggers it, in which case it's likely a lower level bug we can report?