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Testing a Multithreaded/Multicontexted Application
Testing Recommendations for a Multithreaded/Multicontexted Application
We recommend following these recommendations during testing of your multithreaded and/or multicontexted code:
Troubleshooting a Multithreaded/Multicontexted Application
When you need to investigate possible causes of errors, we recommend that you start by checking whether and how the TPMULTICONTEXTS flag has been set. Errors are frequently introduced by failures to set this flag or to set it properly.
Improper Use of the TPMULTICONTEXTS Flag to tpinit( )
If a process includes the TPMULTICONTEXTS flag in a state for which this flag is not allowed (or omits TPMULTICONTEXTS in a state that requires it), then tpinit(3c) returns -1 and sets tperrno to TPEPROTO.
Calls to tpinit( ) Without TPMULTICONTEXTS
When tpinit(3c) is invoked without TPMULTICONTEXTS, it behaves as it does when called in a single-contexted application. When tpinit() has been invoked once, subsequent tpinit() calls without the TPMULTICONTEXTS flag succeed without further action. This is true even if the value of the TUXCONFIG or WSNADDR environment variable in the application has been changed. Calling tpinit() without the TPMULTICONTEXTS flag set is not allowed in multicontext mode.
If a client has not joined an application and tpinit(3c) is called implicitly (as a result of a call to another function that calls tpinit()), then the BEA Tuxedo system interprets the action as a call to tpinit() without the TPMULTICONTEXTS flag for purposes of determining which flags may be used in subsequent calls to tpinit().
For most ATMI functions, if a function is invoked by a thread that is not associated with a context in a process already operating in multicontext mode, the ATMI function fails with tperrno(5)=TPEPROTO.
Insufficient Thread Stack Size
On certain operating systems, the operating system default thread stack size is insufficient for use with the BEA Tuxedo system. Compaq Tru64 UNIX and UnixWare are two operating systems for which this is known to be the case. If the default thread stack size parameter is used, applications on these platforms dump core when a function with substantial stack usage requirements is called by any thread other than the main thread. Often the core file that is created does not give any obvious clues to the fact that an insufficient stack size is the cause of the problem.
When the BEA Tuxedo system is creating threads on its own, such as server-dispatched threads or a client unsolicited message thread, it can adjust the default stack size parameter on these platforms to a sufficient value. However, when an application is creating threads on its own, the application must specify a sufficient stack size. At a minimum, a value of 128K should be used for any thread that will access the BEA Tuxedo system.
On Compaq Tru64 UNIX and other systems on which Posix threads are used, a thread stack size is specified by invoking pthread_attr_setstacksize() before calling pthread_create(). On UnixWare, the thread stack size is specified as an argument to thr_create(). Consult your operating system documentation for further information on this subject.
Error Handling for a Multithreaded/Multicontexted Application
Errors are reported in the user log. For each error, whether in single-context mode or multicontext mode, the following information is recorded:
process_ID.thread_ID.context_ID
See Also
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Copyright © 2000 BEA Systems, Inc. All rights reserved.
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