Tom Lane wrote:
Alvaro Herrera <[EMAIL PROTECTED]> writes:
Martijn van Oosterhout wrote:
The whole semantics of PIPEBUF should prevent garbling, as long as each
write is a complete set of lines and no more than PIPEBUF bytes long.
Have we determined the actual cause of the garbling?

No, that's the main problem -- but it has been reported to happen on
entries shorter than PIPE_BUF chars.

It's not entirely clear to me whether there's been proven cases of
interpolation *into* a message shorter than PIPE_BUF (and remember
you've got to count all the lines when determining the length).
The message intruding into the other could certainly be shorter.

If there have been such cases, then our theories about what's going on
are all wet, or else there are some rather nasty bugs in some kernels'
pipe handling.  So it would be good to pin this down.

Right. But we don't split lines into PIPE_BUF sized chunks. And doing so would make loadable logs possibly rather less pleasant. Ideally we should be able to deal with this despite the PIPE_BUF restriction on atomic writes.



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