Malay Shah created HTTPCORE-753:
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Summary: race condition with CapacityWindow resulting in
CancelKeyException
Key: HTTPCORE-753
URL: https://issues.apache.org/jira/browse/HTTPCORE-753
Project: HttpComponents HttpCore
Issue Type: Bug
Components: HttpCore
Affects Versions: 5.1.3
Reporter: Malay Shah
We have found a race condition AbstractHttp1StreamDuplexer where the
IOSessionImpl is closed off (cancelling it's SelectionKey) first before
CapacityWindow (which also has a reference to the IOSession) is closed. This
creates a window of opportunity where if a ResponseConsumer (something like
AbstractClassicEntityConsumer) holds a reference to the CapacityWindow and
tries to call update(), it will result in a CancelledKeyException being thrown.
We are running into this issue fairly regularly.
Here is what I believe the fix is: in AbstractHttp1StreamDuplexer.onInput the
following two lines should be swapped:
{{dataEnd(contentDecoder.getTrailers());}}
{{capacityWindow.close();}}
Close the capacityWindow first before calling dataEnd which closes off the
connection, thus the capacityWindow will always be safe to use.
In case this is helpful, here is the callstack for when the connection is
closed and the SelectionKey becomes invalid:
{{close:266, IOSessionImpl (org.apache.hc.core5.reactor)}}
{{close:266, InternalDataChannel (org.apache.hc.core5.reactor)}}
{{close:254, InternalDataChannel (org.apache.hc.core5.reactor)}}
{{shutdownSession:157, AbstractHttp1StreamDuplexer
(org.apache.hc.core5.http.impl.nio)}}
{{close:116, ClientHttp1StreamDuplexer$1 (org.apache.hc.core5.http.impl.nio)}}
{{dataEnd:277, ClientHttp1StreamHandler (org.apache.hc.core5.http.impl.nio)}}
{{dataEnd:366, ClientHttp1StreamDuplexer (org.apache.hc.core5.http.impl.nio)}}
{{onInput:333, AbstractHttp1StreamDuplexer (org.apache.hc.core5.http.impl.nio)}}
{{inputReady:64, AbstractHttp1IOEventHandler
(org.apache.hc.core5.http.impl.nio)}}
{{inputReady:39, ClientHttp1IOEventHandler (org.apache.hc.core5.http.impl.nio)}}
{{onIOEvent:131, InternalDataChannel (org.apache.hc.core5.reactor)}}
{{handleIOEvent:51, InternalChannel (org.apache.hc.core5.reactor)}}
{{processEvents:178, SingleCoreIOReactor (org.apache.hc.core5.reactor)}}
{{doExecute:127, SingleCoreIOReactor (org.apache.hc.core5.reactor)}}
{{execute:85, AbstractSingleCoreIOReactor (org.apache.hc.core5.reactor)}}
{{run:44, IOReactorWorker (org.apache.hc.core5.reactor)}}
{{run:829, Thread (java.lang)}}
In the interim, is it safe to catch and discard the CancelledKeyException when
calling update on the CapacityChannel?
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