Nick Houghton created CAMEL-11731:
-------------------------------------
Summary: Servlet Component isn't really async
Key: CAMEL-11731
URL: https://issues.apache.org/jira/browse/CAMEL-11731
Project: Camel
Issue Type: Bug
Components: camel-servlet
Affects Versions: 2.19.2, 2.18.4
Environment: All
Reporter: Nick Houghton
So my assumption reading the servlet component doco is that with 2.18+ and a
Servlet 3+ container, the component supports async, which it kind of does with
the async=true init config, and there is even a method in CamelServlet called
"doServiceAsync" but from what i can tell it doesn't really do it in a
asynchronous manner, where there are no blocked threads while a request is
awaiting an async operation (like an AHC call for example).
Looking at:
https://github.com/apache/camel/blob/master/components/camel-http-common/src/main/java/org/apache/camel/http/common/CamelServlet.java
While processing a request, we check if we are in async mode and call
doServiceAsync..
{code:java}
@Override
protected final void service(HttpServletRequest req, HttpServletResponse
resp) throws ServletException, IOException {
if (isAsync()) {
final AsyncContext context = req.startAsync();
//run async
context.start(() -> doServiceAsync(context));
} else {
doService(req, resp);
}
}
{code}
then in doServiceAsync() we call doService().. and then we call
getProcessor().process(exchange), not process(exchange, asyncCallback) which is
the proper async method..
{code:java}
try {
if (log.isTraceEnabled()) {
log.trace("Processing request for exchangeId: {}",
exchange.getExchangeId());
}
// process the exchange
consumer.getProcessor().process(exchange);
} catch (Exception e) {
exchange.setException(e);
}
{code}
So the actual behaviour is an inbound request in async mode that ends up just
blocking waiting for the request to complete, in a totally sync manner. I
presume this is not the desired behaviour?
It seems the fix would be to move the doService() logic to doServiceAsync() and
have doService() call it and use the AsyncProcessorConverterHelper. Or the
other alternative would be to update the documentation to explicitly note that
it is actually not async at all.
I can probably PR it in, just wanted to get thoughts on the actual intention.
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
