Fixing connection cleanup in case of mass connection breaking. #2614
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CAUSE: In some cases when credentials expire, or servers encounters a blip and closes all connections. The driver gets close message on all connections. While processing those close messages, the driver was getting into race conditions, where in multiple threads were trying to close connections and trying to update the connections object i.e. list of connections in the pool. This was leading to uncaught exceptions and stale connections in the pool. These connections are never cleanedup post this. FIX: Iterate the connections list while creating the connectionPool Info. Since the list used is copyOnWrite, the iterator API creates a clone and uses that clone for referring the element. Thus providing thread safe interface. However the information provided by this iteration is a bit stale, but this doesn't matter.
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Could you rebase and retarget this PR to point to 3.6-dev? This change most likely applies to version 3.6.x and above rather than 4.0.x (master). |
kenhuuu
reviewed
May 22, 2024
| for (int ix = 0; ix < connectionCount; ix++) { | ||
| final Connection c = connections.get(ix); | ||
| if (c.equals(connectionToCallout)) | ||
| final Iterator<Connection> it = connections.iterator(); |
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Minor nit: There aren't any tests for this PR, but this might be ok since appendConnections is only used for logging. But seeing as how we are now dependent on the CopyOnWriteArrayList's iterator behavior, we might want to add a small comment and maybe even explicitly declare connections as a CopyOnWriteArrayList<Connection> rather than just a List<Connection>.
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VOTE +1 pending resolution of some nits. |
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CAUSE:
In some cases when credentials expire, or servers encounters a
blip and closes all connections. The driver gets close message on all
connections. While processing those close messages, the driver was
getting into race conditions, where in multiple threads were trying to
close connections and trying to update the connections object i.e. list
of connections in the pool. This was leading to uncaught exceptions and
stale connections in the pool. These connections are never cleanedup
post this.
FIX:
Iterate the connections list while creating the connectionPool Info.
Since the list used is copyOnWrite, the iterator API creates a clone
and uses that clone for referring the element. Thus providing thread
safe interface.
However the information provided by this iteration is a bit stale, but
this doesn't matter.