Hi, all:
Is there is a way that a thread (when it exits) can tell if there is another
thread joining on it (pthread_join ())? The reason is that if the thread is
created with PTHREAD_CREATE_JOINABLE, I want it to release system resource
when exiting if there is no thread joining on it.
Thanks.
Xuedong
Xuedong Chen wrote in message <9lscp5$30j$1@inn.qnx.com>…
Hi, all:
Is there is a way that a thread (when it exits) can tell if there is
another
thread joining on it (pthread_join ())? The reason is that if the thread is
created with PTHREAD_CREATE_JOINABLE, I want it to release system resource
when exiting if there is no thread joining on it.Thanks.
Xuedong
Why not doing something like this ?
struct my_data_t
{
int joined;
int status;
int pid;
int prio;
int sched;
struct pthread_attr_t attr;
struct sched_param param;
// …
void* (release_fn )( void );
}
inline int my_pthread_create( … )
{
my_data_t dat;
memset( &dat, 0, sizeof( my_data_t ) );
dat.joined = ( … == PTHREAD_CREATE_JOINABLE );
return pthread_create( &dat.pid, &dat.attr, run, (void*)&dat );
}
inline int my_pthread_join( … )
{
return pthread_join( … );
}
void* run( void* info )
{
my_data_t dat;
memcpy( &dat, info, sizeof( my_data_t ) );
// …
dat.release_fn( dat, … );
}
int my_pthread_release_resources( my_data_t data, … ) { }
you can alias alll pthread_* to my_pthread_* with inlined functions to do
what you want.
Another way is to do that via a Thread class, if you prefer a C++ approach.
BTW, when you pthread_join() the second param is a pointer to a function
which
is called when you want to release. But I never used it indirectly via
pthread_create,
if I never join my thread implicitly always explicitely…
Sincerely,
Fred.
Thanks for the detailed information. I will give it a try.
But I was thinking that if there is an OS call which can solve my probem,
since the kernel should have the information that a thread is joined by
other thread or not, right?
Xuedong
“Fred” <fprog@nowhere.users.sourceforge.net> wrote in message
news:9lsev2$463$1@inn.qnx.com…
Xuedong Chen wrote in message <9lscp5$30j$> 1@inn.qnx.com> >…
Hi, all:Is there is a way that a thread (when it exits) can tell if there is
another
thread joining on it (pthread_join ())? The reason is that if the thread
is
created with PTHREAD_CREATE_JOINABLE, I want it to release system
resource
when exiting if there is no thread joining on it.Thanks.
Xuedong
Why not doing something like this ?struct my_data_t
{
int joined;
int status;
int pid;
int prio;
int sched;
struct pthread_attr_t attr;
struct sched_param param;
// …
void* (release_fn )( void );
}inline int my_pthread_create( … )
{
my_data_t dat;
memset( &dat, 0, sizeof( my_data_t ) );
dat.joined = ( … == PTHREAD_CREATE_JOINABLE );
return pthread_create( &dat.pid, &dat.attr, run, (void*)&dat );
}inline int my_pthread_join( … )
{
return pthread_join( … );
}void* run( void* info )
{
my_data_t dat;
memcpy( &dat, info, sizeof( my_data_t ) );
// …dat.release_fn( dat, … );
}int my_pthread_release_resources( my_data_t data, … ) { }
you can alias alll pthread_* to my_pthread_* with inlined functions to do
what you want.Another way is to do that via a Thread class, if you prefer a C++
approach.BTW, when you pthread_join() the second param is a pointer to a function
which
is called when you want to release. But I never used it indirectly via
pthread_create,
if I never join my thread implicitly always explicitely…Sincerely,
Fred.
Probably stored in pthread_attr_t
perhaps, I’m not sure how if this is changed ‘externally’…
It’s quite a black box. Also it might not be portable to other POSIX systems
!
My trick was since you don’t know what’s inside, just build a thin black box
around the existing one. I don’t say it’s efficient or anything.
Maybe someone as a clue ?!
Probably from one of the QNX Kernel Thread functions…
Sincerely,
Fred.
Xuedong Chen wrote in message <9lttdj$2do$1@inn.qnx.com>…
Thanks for the detailed information. I will give it a try.
But I was thinking that if there is an OS call which can solve my probem,
since the kernel should have the information that a thread is joined by
other thread or not, right?Xuedong
“Fred” <fprog@nowhere.users.sourceforge.net> wrote in message
news:9lsev2$463$> 1@inn.qnx.com> …Xuedong Chen wrote in message <9lscp5$30j$> 1@inn.qnx.com> >…
Hi, all:Is there is a way that a thread (when it exits) can tell if there is
another
thread joining on it (pthread_join ())? The reason is that if the thread
is
created with PTHREAD_CREATE_JOINABLE, I want it to release system
resource
when exiting if there is no thread joining on it.Thanks.
Xuedong
Why not doing something like this ?struct my_data_t
{
int joined;
int status;
int pid;
int prio;
int sched;
struct pthread_attr_t attr;
struct sched_param param;
// …
void* (release_fn )( void );
}inline int my_pthread_create( … )
{
my_data_t dat;
memset( &dat, 0, sizeof( my_data_t ) );
dat.joined = ( … == PTHREAD_CREATE_JOINABLE );
return pthread_create( &dat.pid, &dat.attr, run, (void*)&dat );
}inline int my_pthread_join( … )
{
return pthread_join( … );
}void* run( void* info )
{
my_data_t dat;
memcpy( &dat, info, sizeof( my_data_t ) );
// …dat.release_fn( dat, … );
}int my_pthread_release_resources( my_data_t data, … ) { }
you can alias alll pthread_* to my_pthread_* with inlined functions to
do
what you want.Another way is to do that via a Thread class, if you prefer a C++
approach.BTW, when you pthread_join() the second param is a pointer to a function
which
is called when you want to release. But I never used it indirectly via
pthread_create,
if I never join my thread implicitly always explicitely…Sincerely,
Fred.
\
Xuedong Chen (Xuedong.Chen@IGT.com) wrote:
: Hi, all:
: Is there is a way that a thread (when it exits) can tell if there is another
: thread joining on it (pthread_join ())? The reason is that if the thread is
: created with PTHREAD_CREATE_JOINABLE, I want it to release system resource
: when exiting if there is no thread joining on it.
Why do you want to do this? There are two problems with this – a race
condition and an implementation issue.
The race condition stems from the fact that another thread may be just about
to join your thread – due to very short windows, it may or may not join your
thread.
The second issue stems from implementation – how are you actually going to
release the resources of this thread? It certainly can’t join() itself 
Generally, if you’re going to join() the thread, make it joinable, else don’t
make it joinable…
Cheers,
-RK
–
Robert Krten, PARSE Software Devices; email my initials at parse dot com
Consulting, Systems Architecture / Design, Drivers, Training, QNX 4 & Neutrino
Check out our new QNX 4 and Neutrino (QRTP) books at http://www.parse.com/
Wanted PDP-8/9/10/11/12 Systems/documentation/spare parts! Will trade books!