Since the mod_perl's internal STDOUT buffer isn't mangled if you re-tie it later, and it'll be always flushed at the end of the request, there is no *need* to flush on CLOSE. However in order to be consistent with perl fh close behavior, it probably needs to be changed to flush its buffer.
What do you think?
Dunno. But the problem I had would have been even harder to track down if commenting out the flush hadn't fixed it.
The difference between mod_cgi and mod_perl is that mod_cgi does not activate the filter brigade until it has read all the headers.
But in the case of mod_perl, this "event" is valid only for handlers which print their own headers, rather than using mod_perl API to set them. In the generic case, there is no way to tell whether a handler is going to set more headers or it has done with it.
So can flushing be held off until either (1) blank line is printed, (2) the 8k buffer fills, or (3) send_http_header is called?
I suppose that we could prevent flushing in the case the handler is configured to parse headers. Does it make sense?
No. Could you explain your reasoning.
mod_cgi uses spilling buckets, each of size 8K, to buffer script output,
including during the header scan, while mod_perl seems to scan the headers
when the first 8K buffer is either filled or flushed.
I don't think this is related to the issue in question. Since the problem is what to do on flush.
Also we might have a problem if the headers to parse are bigger than the size of the buffer (8k). Do you think someone will ever need to send headers bigger than 8k?
Yes, I mentioned the buffer size in case your objection to my proposal to wait until end of headers was seen was based on the possiblity of more than 8k of headers. With the current mp2 code, if you decide to wait for the end of headers before doing cgi parsing and flushing then the code is assuming that either the headers are less than 8k or that any Status header is in the first 8k. Otherwise the code would have to be re-written to use continuous (spilling and merging) buffer buckets like mod_cgi. It can hold off on flushing indefinitely.
