Question

I have a question: Is there some way to the SPID in linux 2.6 from a C++ application? When I do a ‘ps -amT’ I can see the threads in the process:

root@10.67.100.2:~# ps -amT   PID  SPID TTY          TIME CMD  1120     - pts/1    00:00:20 sncmdd     -  1120 -        00:00:00 -     -  1125 -        00:00:00 -     -  1126 -        00:00:00 -     -  1128 -        00:00:00 -     -  1129 -        00:00:09 -     -  1130 -        00:00:00 -     -  1131 -        00:00:09 -  1122     - pts/1    00:00:00 snstatusdemuxd     -  1122 -        00:00:00 -     -  1127 -        00:00:00 -     -  1132 -        00:00:00 -     -  1133 -        00:00:00 - 

And then in the filesystem I can see the threads:

root@10.67.100.2:~# ls /proc/1120/task/ 1120  1125  1126  1128  1129  1130  1131 

So is there some way I can get the SPID from my application so I can somehow identify what my SPID is in each running thread?

Thanks!

/Mike

Edit: I should add that the PID returned from getpid() is the same in each thread.

When I add this code to my threads:

// Log thread information to syslog syslog(LOG_NOTICE, 'ibnhwsuperv: gettid()= %ld,  pthread_self()=%ld', (long int)syscall(224), pthread_self()); 

I get this result:

Jan  1 01:24:13 10 ibnhwsupervd[1303]: ibnhwsuperv: gettid()= -1,  pthread_self()=839027488 

Neither of which look like the SPID given by ps or in the proc filesystem.

Also, note that gettid does not return the SPID.

Answer 1

How about gettid()?

Edit: If your libc doesn’t have the gettid() function, you should run it like this:

#include <sys/syscall.h> syscall(SYS_gettid); 

… or see example on this manual page.