RE: A question about how to send message in the callback function

["Jeff Hill" <johill@lanl.gov>]

Hello ZHAO HUAN,

 

One must call ca_attach_context from the satellite thread after calling ca_current_context in the main (CA client context initiating) thread. Also see “CA Client Contexts and Application Specific Auxiliary Threads” in the CA Reference Manual. Also see “Thread Safety and Preemptive Callback to User Code”.

 

PS: If you enable preemptive callback be careful to protect your data structures against simultaneous use from multiple threads.

 

Jeff

 

 

-----Original Message-----
From: ÕÔ»¶ [mailto:zhaohuan@sinap.ac.cn]
Sent: Sunday, March 26, 2006 8:52 PM
To: core-talk@aps.anl.gov
Subject: A question about how to send message in the callback function

 

 Dear everybody:

     I am a novice to EPICS. I want to develop a simple

 application which will have functions of put,get and monitor channels in

 IOC. I have installed  EPICS Base R3.14.5 in a PC/Windows .

Now, I face a puzzle.  I cteate a auxiliary thread. And in the auxiliary thread, I do an operation of create a 

monitor(ca_create_subscription). Then in the monitor’s callback faction, I make an operation of sendmessage. The problem 

is coming. The runing programe is dead at the sendmessage step.

       If somebody have the experience,  tell me what is wrong in my application, and how can I resolve it.

  Thanks

  ZHAO HUAN

 Shanghai Institute of Applied Physics

 Chinese Academy of Sciences

 P. O. Box 800-204, Shanghai 201800, P. R. China

 Tel: +86-21-59553146