Stephen Mallette created TINKERPOP-3064:
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Summary: Allow borrowing a connection even if dead
Key: TINKERPOP-3064
URL: https://issues.apache.org/jira/browse/TINKERPOP-3064
Project: TinkerPop
Issue Type: Improvement
Components: driver
Affects Versions: 3.6.6
Reporter: Stephen Mallette
An item for investigation/consideration - we rely on {{Connection.isDead()}}
when borrowing a connection (in {{getLeastUsedVaildConnection()}}) and if true
it's ignored. So, dead connections won't be borrowed and a new connection will
be considered and we'll end up in {{waitForConnection}} which will keep trying
that cycle.
On a related note, {{Connection.isDead()}} is really just grabbing boolean
values set by native code and as such ["you cannot be sure that the connection
is still working at the moment you call the
function"|https://stackoverflow.com/questions/34637911/how-channel-isactive-works-in-netty].
Since the driver only destroy/replace connections on the return of a
connection, certain cases where there are channel errors and for complete
disconnection of the {{Host}} and because calls to {{isDead()}} don't really
give a perfect picture of the state of the driver, perhaps we should
re-evaluate where/how {{isDead()}} is used? like, what if it was not used
during connection borrowing, it could borrow one that was dead, it would fail
and then head to replacement, rather than sit in the pool. would that be a more
efficient handling of the pool and to shorten wait times for a connection?
perhaps the driver is being too safe in this way? maybe {{isDead()}} switches
to true in the time the driver writes to it? not sure if that theory holds
water exactly but seems worth investigating a bit.
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