libtha(3)libtha(3)NAMElibtha - API that can be used in conjunction with the Sun Studio Thread
Analyzer
SYNOPSIS -- C and C++ Version of the API
cc [ options ] file -ltha -Linstall_path/lib -Rinstall_path/lib
CC [ options ] file -ltha
#include "tha_interface.h"
void tha_notify_acquire_lock (uintptr_t id);
void tha_notify_lock_acquired (uintptr_t id);
void tha_notify_acquire_writelock (uintptr_t id);
void tha_notify_writelock_acquired (uintptr_t id);
void tha_notify_acquire_readlock (uintptr_t id);
void tha_notify_readlock_acquired (uintptr_t id);
void tha_notify_release_lock (uintptr_t id);
void tha_notify_lock_released (uintptr_t id);
void tha_notify_sync_post_begin (uintptr_t id);
void tha_notify_sync_post_end (uintptr_t id);
void tha_notify_sync_wait_begin (uintptr_t id);
void tha_notify_sync_wait_end (uintptr_t id); void
tha_check_datarace_mem (uintptr_t addr, size_t size, int onoff);
void tha_check_datarace_thr (int selfall, int onoff);
SYNOPSIS -- Fortran Version of the API
f95 [ options ] file -ltha
include "tha_finterface.h"
subroutine tha_notify_acquire_lock (id)
integer(kind=tha_sobj_kind) :: id
subroutine tha_notify_lock_acquired (id)
integer(kind=tha_sobj_kind) :: id
subroutine tha_notify_acquire_writelock (id)
integer(kind=tha_sobj_kind) :: id
subroutine tha_notify_writelock_acquired (id)
integer(kind=tha_sobj_kind) :: id
subroutine tha_notify_acquire_readlock (id)
integer(kind=tha_sobj_kind) :: id
subroutine tha_notify_readlock_acquired (id)
integer(kind=tha_sobj_kind) :: id
subroutine tha_notify_release_lock (id)
integer(kind=tha_sobj_kind) :: id
subroutine tha_notify_lock_released (id)
integer(kind=tha_sobj_kind) :: id
subroutine tha_notify_sync_post_begin (id)
integer(kind=tha_sobj_kind) :: id
subroutine tha_notify_sync_post_end (id)
integer(kind=tha_sobj_kind) :: id
subroutine tha_notify_sync_wait_begin (id)
integer(kind=tha_sobj_kind) :: id
subroutine tha_notify_sync_wait_end (id)
integer(kind=tha_sobj_kind) :: id
subroutine tha_check_datarace_mem (addr, mem_size, onoff)
integer(kind=tha_sobj_kind), intent(in) :: addr
integer(kind=4), intent(in) :: mem_size
integer(kind=4), intent(in) :: onoff
subroutine tha_check_datarace_thr (selfall, onoff)
integer(kind=4), intent(in) :: selfall
integer(kind=4), intent(in) :: onoff
DESCRIPTION
The shared object, libtha.so, provides an API that can be used in con‐
junction with the Sun Studio Thread Analyzer. The API routines may be
used to notify the Thread Analyzer about synchronizations, or to con‐
trol data-race detection.
Note that libtha.so provides only "hook" (or dummy) entry points for
the API routines. This allows programs that call these routines and
that are linked with libtha.so to run outside of a Thread Analyzer
experiment, as well as inside such an experiment.
If the program is run outside a Thread Analyzer experiment (i.e., the
program is neither run under collect -r race nor run under collect -r
deadlock), then the API routines will not have any effect.
If the program is run under a Thread Analyzer experiment (i.e., the
program is run under collect -r race or collect -r deadlock), then the
routines have an effect.
See collect(1) for more information about performing a Thread Analyzer
experiment.
LIBTHA SYNCHRONIZATION ROUTINES
The Thread Analyzer can recognize most standard synchronization APIs
and constructs provided by OpenMP, POSIX threads, and Solaris threads.
However, the tool cannot recognize roll-your-own style synchroniza‐
tions, and may report false data-races if such synchronizations are
used. For example, the tool cannot recognize spin locking implemented
using hand-coded assembly.
If your program includes roll-your-own style synchronizations, then you
can insert calls to the libtha.so API in the program to inform the
Thread Analyzer of those synchronizations. These calls allow the tool
to recognize the synchronizations, thus reducing the number of false-
positive data-races reported.
The libtha.so API consists of the following synchronization routines:
tha_notify_acquire_lock(): This routine can be called immediately
before the program tries to acquire a user-defined lock.
tha_notify_lock_acquired(): This routine can be called immediately
after a user-defined lock has been acquired successfully.
tha_notify_acquire_writelock(): This routine can be called immediately
before the program tries to acquire a user-defined read/write lock in
write mode.
tha_notify_writelock_acquired(): This routine can be called immediately
after a user-defined read/write lock has been acquired successfully in
write mode.
tha_notify_acquire_readlock(): This routine can be called immediately
before the program tries to acquire a user-defined read/write lock in
read mode.
tha_notify_readlock_acquired(): This routine can be called immediately
after a user-defined read/write lock has been acquired successfully in
read mode.
tha_notify_release_lock(): This routine can be called immediately
before a user-defined lock (including a read/write lock) is to be
released.
tha_notify_lock_released(): This routine can be called immediately
after a user-defined lock (including a read/write lock) has been
released successfully.
tha_notify_sync_post_begin(): This routine can be called immediately
before a user-defined post synchronization is performed.
tha_notify_sync_post_end(): This routine can be called immediately
after a user-defined post synchronization has been performed.
tha_notify_sync_wait_begin(): This routine can be called immediately
before a user-defined wait synchronization is performed.
tha_notify_sync_wait_end(): This routine can be called immediately
after a user-defined wait synchronization has been performed.
In the C/C++ version of the libtha API, each of the above routines
takes a single argument, id, whose value should uniquely identify the
synchronization object. The type of id is uintptr_t, which is defined
in <sys/types.h>. The size of id is 4 bytes in 32-bit mode and 8 bytes
in 64-bit mode.
In the Fortran version of the libtha API, each of the above routines
takes a single argument, id, whose value should uniquely identify the
synchronization object. The type of id is integer, and its size is
given by tha_sobj_kind which is defined in tha_finterface.h to be 8
bytes in both 32-bit and 64-bit modes.
To uniquely identify a synchronization object, you should make sure
that the argument id has a different value for each different synchro‐
nization object. One way to do this is to let the value of id be the
address of the synchronization object. That address can be obtained
using the & operator in C/C++, or using the loc() library routine in
Fortran. See Example 1 under the EXAMPLES section below.
LIBTHA ROUTINES FOR CONTROLLING DATA-RACE DETECTION
You can insert calls in your program to the libtha.so API to control
data-race detection.
tha_check_datarace_mem(): This routine instructs the Thread Analyzer to
monitor or ignore accesses to a specified block of memory when doing
data-race detection. When the onoff parameter is THA_CHK_OFF, data-
race detection on the specified block of memory is turned off. When the
onoff parameter is THA_CHK_ON, data-race detection on the specified
block of memory is turned on. When onoff is neither THA_CHK_OFF nor
THA_CHK_ON, the behavior of the call is undefined. The block of memory
starts at addr and has size bytes. When addr is NULL and size is zero,
the block of memory is considered to be all memory. The Thread Analyzer
monitors all memory accesses by default when data-race detection is on.
Note that if multiple calls that affect the same block of memory are
made by different threads, the calls take effect in the order they are
received by the Thread Analyzer. You might want to properly synchronize
these calls. Calls to this routine have no effect when data-race detec‐
tion is not turned on by the collect(1) command.
tha_check_datarace_thr(): This routine instructs the Thread Analyzer to
monitor or ignore memory accesses by one or more specified threads when
doing data-race detection. When the onoff parameter is THA_CHK_OFF,
data-race detection on the specified threads is turned off. When the
onoff parameter is THA_CHK_ON, data-race detection on the specified
threads is turned on. When onoff is neither THA_CHK_OFF nor
THA_CHK_ON, the behavior of the call is undefined. When the selfall
parameter is THA_CHK_THR_SELF, it only affects the calling thread (that
is, data-race detection on the calling thread only is turned on/off).
When the selfall parameter is THA_CHK_THR_ALL, it affects all threads
including new threads created after this call (that is, data race
detection is turned off for all threads). When the selfall parameter is
neither THA_CHK_THR_SELF nor THA_CHK_THR_ALL, the behavior of the call
is undefined. The Thread Analyzer mointors all threads by default when
data-race detection is on. Note that if multiple calls that affect the
same thread are made by different threads, the calls take effect in the
order they are received by the Thread Analyzer. You might want to prop‐
erly synchronize these calls. Calls to this routine have no effect when
data-race detection is not turned on by the collect(1) command.
See Examples 3 and 4 under the EXAMPLES section below.
EXAMPLES
Example 1:
The following Fortran example shows how tha_notify_acquire_lock() and
tha_notify_release_lock() can be used to inform the Thread Analyzer
that a user-defined lock has been acquired and released, respectively.
In this example, the address of the lock object is used as id to
uniquely identify the object.
include "tha_finterface.h"
integer :: my_lock
integer(kind= tha_sobj_kind) :: id
id = loc (my_lock)
tha_notify_acquire_lock (id)
call my_lock_routine(my_lock)
tha_notify_lock_acquired (id)
...
call my_unlock_routine(my_lock)
tha_notify_lock_released (id)
Example 2:
The following C/C++ example shows how tha_notify_sync_wait_begin() and
tha_notify_sync_wait_end() can be used to inform the Thread Analyzer of
the start and end of a user-defined wait synchronization, respectively.
In addition, the example shows how tha_notify_sync_post_begin() and
tha_notify_sync_post_end() can be used immediately before and after a
post synchronization, respectively.
#include "tha_interface.h"
int busy_wait = 1;
/* Code executed by thread 1 */
tha_notify_sync_wait_begin(&busy_wait);
while (busy_wait) {
no_op();
}
tha_notify_sync_wait_end(&busy_wait);
/* Code executed by thread 2 */
tha_notify_sync_post_begin(&busy_wait);
busy_wait = 0;
tha_notify_sync_post_end(&busy_wait);
Example 3:
The following C/C++ example shows how tha_check_datarace_mem() can be
used to avoid reporting benign data races.
volatile int is_bad = 0;
/*
* Each thread checks its assigned portion of data_array,
* and sets the global flag is_bad to 1 once it finds a
* bad data element.
*/
void check_bad_array (volatile data_t *data_array,
unsigned int thread_id) {
/* Do not check is_bad. */
tha_check_datarace_mem(&is_bad, sizeof(int), THA_CHK_OFF);
int i;
for (i=my_start(thread_id); i<my_end(thread_id); i++) {
if (is_bad)
break;
else {
if (is_bad_element(data_array[i])) {
is_bad = 1;
break;
}
}
}
tha_check_datarace_mem(&is_bad, sizeof(int), THA_CHK_ON);
}
Example 4:
The following C/C++ example shows how tha_check_datarace_thr() can be
used to lower the overhead of data-race detection, supposing that the
programmer wishes only to check data-race between 2 particular threads.
/*
* The following code is executed by the master thread.
* Before creating any slave threads, the master thread
* turns data race detection off for all threads.
*/
tha_check_datarace_thr(THA_CHK_THR_ALL, THA_CHK_OFF);
pthread_create(...);
/*
* The following code is executed by the slave threads.
* After a slave thread is created, it checks whether
* it should turn data race detection on for itself.
*/
pthread_t tid = pthread_self();
if(tid == TID_TO_CHECK_1 || tid == TID_TO_CHECK_2)
tha_check_datarace_thr(THA_CHK_THR_SELF, THA_CHK_ON);
NOTES
As shown in the synopsis, the recommended way to link with libtha using
cc is to specify
-Rinstall-path/lib -Linstall-path/lib -ltha
on the command line, where install-path refers to the location in which
the compilers are installed (by default /opt/sunstudio12.1 on Solaris
systems and /opt/sun/studio12.1 on Linux systems).
ATTRIBUTES
_________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|__________________|______________________________________|
| Stability Level | Evolving. |
|__________________|______________________________________|
SEE ALSOtha(1), analyzer(1), collect(1), collector(1), er_print(1),
attributes(5), and the Performance Analyzer manual.
March 2009 libtha(3)
