Re: signed logging format for pid in log_line_prefix?

Greg Stark <stark(at)mit(dot)edu> writes:
> Both the text and csv logging seem to use %d on for logging the server pid:
> appendStringInfo(buf, "%d", MyProcPid);

> Am I missing something or wouldn't this mean we print pids with large
> values as negative numbers? Isn't that strange? Wouldn't we rather use
> %u here?

pid_t is a signed type; see for example waitpid(2):

The value of pid can be:

< -1 meaning wait for any child process whose process group ID is
equal to the absolute value of pid.

-1 meaning wait for any child process.

0 meaning wait for any child process whose process group ID is
equal to that of the calling process.

> 0 meaning wait for the child whose process ID is equal to the
value of pid.

So I think using %d is fine. Someday we might wish that we were using
a wider type than int to hold PIDs, but I don't think it'll ever be
unsigned.

regards, tom lane