Hello Patrick, Manjula kindly provided a best-practice example for how to do multi-threading with Axis2/C [1] (at least on the client side) if I remember correctly, it was one environment per thread, and the stubs were per call? Well in his example it is svc_client and not stub, but if I understand correctly, those two concepts are one-to-one, meaning one stub has one svc_client.
>From my point of view it seems the troubles you are encountering are based in areas where Axis does little or nothing to help the programmer. I have not seen any code to manage thread creation and resources acces in the Axis2/C project. Problems like resource deadlock on the configuration file are outside the scope of what Axis2/C has to offer. What Axis does well is freeing resources (once we figure out how to set everything up right!) so I am a little confused as to where exactly the limitations are. You say the callback system provided is not good in terms of freeing resources, but have you tried freeing your resources from another function which itself waits for the callback to occur? (either error callback or success callback) I think this is the way Axis was designed with as implied by Dimuthu: wait in a loop in your main thread while the callbacks are outstanding, do no cleanup in the callback itself, let that thread exit completely and after it is done, then from your main thread detect that the callback ocurred and do the cleanup there. For environment vs stub issues, there is no alternative but to take ownership of this problem directly and implement some synchronisation outside the scope of Axis2/C. Your code synchronises creation of threads and initialisation to avoid having deadlock problems. Maybe there is some improvement to be made to Axis here? My reason for responding though is really to comment on this phrase: "Threads are a rather expensive resource to use for just waiting on an IO completion". It may be my lack of understanding, but I am pretty sure that -- at least in the win32 tcp/ip stack -- once your thread goes into asynchronous communication on a socket, you do not see it again until there is some result. This means if there is a timeout your thread is inactive for a long time. How can one thread wait on more than one asychronous communication? I admit this would be a far better solution, however from my understanding of winsock2 it is not possible. Seen this way, one thread per socket communication is maybe expensive in resources, but it is the only way to ensure your main thread continues to operate in a timely fashion. Hth Carl [1] http://marc.info/?l=axis-c-user&m=118404667311058&w=2 -----Message d'origine----- De : Patrick van Beem [mailto:[EMAIL PROTECTED] Envoyé : jeudi, décembre 11, 2008 05:46 À : axis-c-dev@ws.apache.org Objet : Multi-threading Hello, I'm experiencing serious limitations while using axis in a multi-threading environment. I know axis is not fully designed (yet?) for multi-threading, but I think some 'small' changes might make it more usable. One can't deny multi-threading. Here my 2 cents: * Callback and resources In a multi-threading environment, an asynchronous job is often responsible for freeing it's own resources (in this case, the environment, the stub and possible extra application dependent data). In the axis framework, this can't be done in the callback, since the framework will use the stub after the callback is finished. This makes it impossible for an application to free resources after a call has finished (because you never know exactly when the call (including the framework part of it) is finished. This makes the asynchronous implementation of axis useless in a job-oriented multi-threading environment. Improvements might include adding an extra callback to free resources, that is made when axis has freed all its resources and does not need any resources the user might free. * Environment vs stub Since every thread needs it's own environment and stub in axis and (as stated above) in a multi-threaded environment a job is often responsible of it's own resources, every job needs to allocate and initialize it's environment and stub for each call (or keep one set initialized for every thread, but that's not feasible when one thread can be used for multiple purposes / jobs and/or threads can be added dynamically). And free it after the job is finished. Apart from the (slight) performance drawback, this poses another problem: Part of the stub initialization includes reading the configuration file. When two threads try to do this simultaneously, the last one who tries this, fails. Solutions to this problem might include: - Create a clone function for the stub, so all threads can clone from template stub, instead of reading from disk. - Separate the state information from the stub and put it in the environment, so the stub can be used read-only and shared by threads. * Async model The asynchronous call implementation of axis is based on creating new threads that just wait on a response. Threads are a rather expensive resource to use for just waiting on an IO completion (and then performing some small task). It might be better that the waiting on all outstanding IO is done by one single thread. The work after the IO completed can then be done by either that thread, or a (small and static) thread pool. That way, no threads have to be created / deleted on the flow, not more than one thread is waiting on IO and no high amount of threads will exist when a lot of asynchronous calls exist in parallel. My axis knowledge is not enough to see solutions for this within axis right now. What do you all think about these points? Regards, -- Patrick van Beem Sr. Software engineer Quintiq T +31 (0) 73 691 07 39 F +31 (0) 73 691 07 54 M +31 (0) 06 15 01 65 83 E [EMAIL PROTECTED] I www.quintiq.com This message contains information that may be privileged or confidential and is the property of Quintiq. It is only intended for the person to whom it is addressed. If you are not the intended recipient, you are not authorized to read, print, retain, copy, disseminate, distribute or use this message or any part thereof. If you have received this message in error, please notify the sender immediately and delete all copies of this message. 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