For instance: 25301 rt_sigaction(SIGCHLD, {0x4db772, [], SA_RESTORER, 0x94b7c8}, {SIG_DFL}, 8) = 0 25301 rt_sigaction(SIGCHLD, {0x80f7f1c, ~[RTMIN RT_1], SA_RESTORER, 0x94b7c8}, NULL, 8) = 0 (the event-loop thread is was thread 25301)
Sonce we've got system-call tracing and back-trace, we can use frysk to find out what is up.