If you have a common broker feed daemon then likely you don't want to
create superfluous shared mem buffers for the same symbol. This adds an
ad hoc little context manger which keeps a bool state of whether
a buffer writer task currently is running in this process. Before we
were checking the shared array token cache and **not** clearing it when
the writer task exited, resulting in incorrect writer/loader logic on
the next entry..
Really, we need a better set of SC semantics around the shared mem stuff
presuming there's only ever one writer per shared buffer at given time.
Hopefully that will come soon!
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