Experimental Physics and
Industrial Control System

Dirk Zimoch via Core-talk <[email protected]> · Wed, 3 Apr 2019 11:37:40 +0200

Hi Martin,

Try on a system that supports thread priorities (on Linux that requires

to run the ioc as root ... or maybe to use "capabilities" which I never

found out how to use without being root in the first place) and use a

higher priority for the new thread than for the parent thread.

Without priorities, I think the only way would be to use event

semaphores like this:

void myThread::run()
{
  std::cerr << "myThread::run() begin\n";
  epicsThreadSleep(3);
  std::cerr << "myThread::run() end\n";
  epicsEventSignal(done);
}

int main() {
  {
    myThread t1(0, "foo");
    epicsEventWait(done);
  }
}

Wait inside the {} before your thread object goes out of context and the

destructor is called.

Actually it may also work with putting the epicsThreadSleep(); inside

the {}:

int main() {
  {
    myThread t1(0, "foo");
    epicsThreadSleep(5);
  }
}

I have not tested anything of the above. So it may or may not work.

Dirk

On 02.04.19 23:35, Konrad, Martin via Core-talk wrote:

Hi,
I have a bunch of unit tests for support modules that spawn epicsThreads
and tear them down after a very short time. I noticed that although I'm
waiting for the thread to shut down cleanly tests are not reproducible.
In the attached simple code snipped I sometimes see the thread function
running:

$ time ./a.out
myThread::myThread() begin
myThread::myThread() end
myThread::~myThread() begin
myThread::run() begin
myThread::run() end
myThread::~myThread() end

real    0m8.044s
user    0m0.025s
sys     0m0.024s

However, sometimes the destructor gets called so fast that the thread
function doesn't run:

$ time ./a.out
myThread::myThread() begin
myThread::myThread() end
myThread::~myThread() begin
myThread::~myThread() end

real    0m5.041s
user    0m0.014s
sys     0m0.031s

I'm wondering if there is a way I can ensure run() always runs. I'm
wondering if making the constructor wait until run() actually starts
executing.

Thanks,

Martin

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System