10:17 p.m.
Tarek Hammoud [https://community.jboss.org/people/thammoud] created the discussion
"Re: Calls against multiple servers from a single client"
To view the discussion, visit: https://community.jboss.org/message/759498#759498
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If you look at the bolded code in EJBInvocationHandler:
Object doInvoke(final T proxy, final Method method, final Object[] args) throws Throwable
{
final MethodHandler handler = clientSideMethods.get(new MethodKey(method));
if (handler != null && handler.canHandleInvocation(this, proxy, method,
args)) {
return handler.invoke(this, proxy, method, args);
}
* final EJBClientContext context = EJBClientContext.requireCurrent();*
return doInvoke(this, async, proxy, method, args, context);
}
EJBClientContext is using a non-thread local static. I don't know how to make that
thread safe with the above suggestions. Looking forward to hearing from you.
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9:33 a.m.
Wolf-Dieter Fink [https://community.jboss.org/people/wdfink] created the discussion
"Re: Calls against multiple servers from a single client"
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Hi Tarek,
I suppose you have knowledge with former AS versions.
Throw the knowlege about ejb-clients away, it's complete different.
Since AS7 the Proxy (stub) does not contain any information about the server, it is only a
implementation of the Interface that is created by reflection during runtime lookup().
The Proxy knows only the name "ejb:app/module/distinct/bean!view".
If you execute a method the ejb-client library decide how to go, here is the knowlege what
server exists set by the initial creation or the jboss-ejb-client.properties.
The selector handle the phys. connections to the servers and I'm not sure what happen
in your case setting the selectors for each call, regardless that such sync-block might be
a concurrency bottleneck.
Le me finish my example I mentioned above and it might will give you an idea.
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12:23 p.m.
Tarek Hammoud [https://community.jboss.org/people/thammoud] created the discussion
"Re: Calls against multiple servers from a single client"
To view the discussion, visit: https://community.jboss.org/message/759575#759575
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Hi Wolf,
The sync call (Labeld Evil) is used in the example above of what a multithreaded client
will have to do and avoid the selector trashing and function properly albeit serially. It
is not used for to demonstrate "best practices". Out multi-server test cases
broke immediately in AS7 thus the hack to show the extent of this problem. I believe that
the EJBClientContext with a static selector inhibits proper implementation of a
multithreaded client in AS7.
Tarek
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12:31 p.m.
Wolf-Dieter Fink [https://community.jboss.org/people/wdfink] created the discussion
"Re: Calls against multiple servers from a single client"
To view the discussion, visit: https://community.jboss.org/message/759579#759579
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Tarek Hammoud wrote:
I believe that the EJBClientContext with a static selector inhibits proper implementation
of a multithreaded client in AS7.
That will not be true, it is possible to have
multithread clients with AS7, but as I mentionend it is completly different in
implmentation and use.
So what is your exact requirement. Do you
- deploy the same applcation at different servers with different credentials and need to
decide which one is called?
- deploy different EJBs spread on servers and want to call it? Simple, add all servers to
the ejb-client.properties and call the different names
Wolf
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2:26 p.m.
Tarek Hammoud [https://community.jboss.org/people/thammoud] created the discussion
"Re: Calls against multiple servers from a single client"
To view the discussion, visit: https://community.jboss.org/message/759595#759595
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Hi Wolf,
Deploy the same applcation at different servers with different credentials and need to
decide which one is called?
That is one of the use cases.
That will not be true, it is possible to have multithread clients
with AS7, but as I mentionend it is completly different in implmentation and use.
This why I opened this ticket. While the framework clearly allows for multiple targets and
there is nothing to inhibit a multithreaded client, I am pointing out a race condition in
the implementation with respect to static in EJBContext. Again, looking at the
EJBInvocationHandler, you can clearly see that it is indirectly manipulating a static
member by calling the requireCurrent(). Two threads in the EJBInvocationHandler doInvoke
code can end up pointing to the wrong SELECTOR.
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10:50 p.m.
Radek Rodak [https://community.jboss.org/people/rodakr] created the discussion
"Re: Calls against multiple servers from a single client"
To view the discussion, visit: https://community.jboss.org/message/764191#764191
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Terek is right
Try Simple example.
One Stand alone Client starting 2 Threads. Each Thread calls an EJB on different JBoss 7x
Server. Once Static EJBClientContext.setSelector is called seconde times, it brakes one of
both Threads...
no EJBRecever avaible exception... 25 is the result. I don't see any sinfull solution
as long as global static EJBClientContext.setSelector is needed!!!
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participants (3)
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Radek Rodak -
Tarek Hammoud
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Wolf-Dieter Fink