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Subject: Graceful Shutdown with joinable thread
From: "Kim, Kukhee via Core-talk" <core-talk at aps.anl.gov>
To: EPICS core-talk <core-talk at aps.anl.gov>
Date: Wed, 1 Apr 2020 15:59:46 +0000
Hi Everyone,

I recently worked for some epics drivers to implement a graceful shutdown and got a question.
The drivers are SLAC specific but the question is general.

I saw there are some API changes to allow joinable thread.
Thus, I used it: "epicsThreadCreateOpt() with joinable option, and epicsThreadMustJoin()"

It looks mostly the same as the old way but is slightly better personally.

old way:
  • The  exit hook breaks  an infinite loop in driver thread
  • driver thread send an event when it returns
  • main thread (the exit hook) waits the event from the driver thread then exits

new with joinable thread:
  • The exit hook breaks an infinite loop in the driver thread
  • driver thread simply returns 
  • main thread (the exit hook) waits with epicsThreadMustJoin() then exits
There is a small downside: more steps to create thread - I have to set up a thread option structure before calling epicsThreadCreateOpt(),
Since, the un-joinable thread is default and it is for backward compatibility.

I am wondering about our evolutional direction:
Are we going to keep the un-joinable thread as a default? Or, migrate to the joinable thread?


Thank you for your advice.
I hope everyone keeps stay healthy and safe.

Best regards,
Kukhee

Kukhee Kim

TID AIR Advanced Control System

SLAC National Accelerator Laboratory

2575 Sand Hill Rd, MS 94

Menlo Park, CA 94025

Email: khkim at SLAC.Stanford.EDU

Phone: (650)926-4912

Fax:   (650)926-2923

Replies:
Re: Graceful Shutdown with joinable thread Johnson, Andrew N. via Core-talk
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