vignesh C <vignes...@gmail.com> writes: > The idea here is to implement & expose pg_print_callstack function, > internally what this function does is, the connected backend will send > SIGUSR1 signal by setting PMSIGNAL_BACKTRACE_EMIT to the postmaster > process. Postmaster process will send a SIGUSR1 signal to the process > by setting PROCSIG_BACKTRACE_PRINT if the process has access to > ProcSignal. As syslogger process & Stats process don't have access to > ProcSignal, multiplexing with SIGUSR1 is not possible for these > processes, hence SIGUSR2 signal will be sent for these processes. Once > the process receives this signal it will log the backtrace of the > process.
Surely this is *utterly* unsafe. You can't do that sort of stuff in a signal handler. It might be all right to set a flag that would cause the next CHECK_FOR_INTERRUPTS to print a backtrace, but I'm not sure how useful that really is. The proposed postmaster.c addition seems quite useless, as there is exactly one stack trace it could ever log. I would like to see some discussion of the security implications of such a feature, as well. ("There aren't any" is the wrong answer.) regards, tom lane