#include <qp0ztrc.h>
int Qp0zDumpTargetStack(int handle,
const char *label);
The Qp0zDumpTargetStack() function dumps a formatted representation of the call stack of the target thread to the user trace. The target thread is specified by handle, which can be filled in using the pthread_t structure. The formatted call stack is labeled with the text string specified by label. The formatted call stack shows the library, program, module, and procedure information associated with each frame on the call stack at the time the function was called.
The formatted dump of the target call stack shows the oldest entries first, followed by newer entries.
For consistent results, ensure that the target thread specified in the handle parameter is blocked or waiting for some resource and not actively running.
If a target thread that is actively running is specified, the stack trace information may be inconsistent.
An application should not use the tracing function in performance critical code. These functions are intended for debugging exception or error conditions. The user trace is a permanent user space object named QP0Z<jobnumber> in the QUSRSYS library. The user trace is created the first time any thread in a job writes trace output. See the Change User Trace (CHGUSRTRC), Dump User Trace (DMPUSRTRC) and Delete User Trace (DLTUSRTRC) CL commands for information about manipulating the user trace properties and objects.
None.
| 0 | Qp0zDumpTargetStack() was successful. |
| value | Qp0zDumpTargetStack() was not successful. The value returned is an errno indicating the failure. |
If Qp0zDumpTargetStack() is not successful, the return value usually indicates one of the following errors. Under some conditions, the return value could indicate an error other than those listed here.
The address used for an argument is not correct.
In attempting to use an argument in a call, the system detected an address that is not valid.
While attempting to access a parameter passed to this function, the system detected an address that is not valid.
No item could be found that matches the specified value.
See Code disclaimer information for information pertaining to code examples.
The following example uses Qp0zDumpTargetStack() and Qp0zUprintf() functions to produce trace output.
#define _MULTI_THREADED
#include <pthread.h>
#include <milib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <qp0ztrc.h>
void *threadfunc(void *);
int main(int argc, char **argv)
{
int rc=0;
pthread_t thread;
Qp0zUprintf("Entering Testcase\n");
rc = pthread_create(&thread, NULL, threadfunc, NULL);
sleep(2); /* Let the thread block */
/* If the other thread ends or is actively running (that is */
/* changing the call stack, you may get meaningless results in the*/
/* stack dump for the target thread.) */
Qp0zDumpTargetStack(thread.reservedHandle,
"Dumping target thread's stack\n");
Qp0zUprintf("Exit with return code of 0\n");
return 0;
}
void foo(void);
void bar(void);
void *threadfunc(void *parm)
{
Qp0zUprintf("Inside secondary thread\n");
foo();
return NULL;
}
void foo(void)
{
bar();
}
void bar(void)
{
Qp0zDumpStack("Thread dumping my own stack\n");
sleep(10); /* Ensure the thread is blocked */
}
This trace output was generated after the test case was run by using the CL command DMPUSRTRC JOB(107141/USER/TPZTSTK0) OUTPUT(*STDOUT). The above example program ran as job 107141/USER/TPZTSTK0.
Note the following in the trace output:
User Trace Dump for job 107141/USER/TPZTSTK0. Size: 300K, Wrapped 0 times. --- 01/23/1998 12:38:10 --- 00000036:595584 Entering Testcase 00000037:598832 Inside secondary thread 00000037:599024 Stack Dump For Current Thread 00000037:599200 Stack: Thread dumping my own stack 00000037:695440 Stack: Library / Program Module Stmt Procedure 00000037:752984 Stack: QSYS / QLESPI QLECRTTH 774 : LE_Create_Thread2__FP12crtth_parm_t 00000037:805664 Stack: QSYS / QP0WPTHR QP0WPTHR 1006 : pthread_create_part2 00000037:805888 Stack: QP0WTEST / TPZTSTK0 TPZTSTK0 2 : threadfunc 00000037:806088 Stack: QP0WTEST / TPZTSTK0 TPZTSTK0 1 : foo 00000037:806288 Stack: QP0WTEST / TPZTSTK0 TPZTSTK0 1 : bar 00000037:806496 Stack: QSYS / QP0ZCPA QP0ZUDBG 85 : Qp0zDumpStack 00000037:848280 Stack: QSYS / QP0ZSCPA QP0ZSCPA 274 : Qp0zSUDumpStack 00000037:848504 Stack: QSYS / QP0ZSCPA QP0ZSCPA 285 : Qp0zSUDumpTargetStack 00000037:848616 Stack: Completed --- 01/23/1998 12:38:12 --- 00000036:628272 Stack Dump For Target Thread: Handle 7 (0x00000007) 00000036:628464 Stack: Dumping target thread's stack 00000036:651608 Stack: Library / Program Module Stmt Procedure 00000036:651872 Stack: QSYS / QLESPI QLECRTTH 774 : LE_Create_Thread2__FP12crtth_parm_t 00000036:652088 Stack: QSYS / QP0WPTHR QP0WPTHR 1006 : pthread_create_part2 00000036:652304 Stack: QP0WTEST / TPZTSTK0 TPZTSTK0 2 : threadfunc 00000036:652512 Stack: QP0WTEST / TPZTSTK0 TPZTSTK0 1 : foo 00000036:652712 Stack: QP0WTEST / TPZTSTK0 TPZTSTK0 2 : bar 00000036:677456 Stack: QSYS / QP0SSRV1 QP0SLIB 1061 : sleep 00000036:700096 Stack: QSYS / QP0SSRV2 QP0SWAIT 248 : qp0swait__FP13qp0ssigwait_t 00000036:700216 Stack: Completed 00000036:700408 Exit with return code of 0 Press ENTER to end terminal session.
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