The ngx_chain_update_chains() needs pool to free chain links used for buffers
with non-matching tags. Providing one helps to reduce memory consumption
for long-lived requests.
There were 2 buffers allocated on each buffer chain sent through chunked
filter (one buffer for chunk size, another one for trailing CRLF, about
120 bytes in total on 32-bit platforms). This resulted in large memory
consumption with long-lived requests sending many buffer chains. Usual
example of problematic scenario is streaming though proxy with
proxy_buffering set to off.
Introduced buffers reuse reduces memory consumption in the above problematic
scenario.
See here for initial report:
http://mailman.nginx.org/pipermail/nginx/2010-April/019814.html
- Agreed that examples can only contain literal text.
- Agreed to call modules "ngx_*_module".
- Renamed XML element "http-error" to a more general "http-status".
- Fixed text of error codes to match the actual code.
If file inode was not changed, cached file information was not updated
on retest. As a result stale information might be cached forever if file
attributes was changed and/or file was extended.
This fix also makes obsolete r4077 change of is_directio flag handling,
since this flag is updated together with other file information.
On file retest open_file_cache lost is_directio if file wasn't changed.
This caused unaligned operations under Linux to fail with EINVAL.
It wasn't noticeable with AIO though, as errors wasn't properly logged.
Read event should be blocked after reading body, else undefined behaviour
might occur on additional client activity. This fixes segmentation faults
observed with proxy_ignore_client_abort set.
Setting read->eof to 0 seems to be just a typo. It appeared in
nginx-0.0.1-2003-10-28-18:45:41 import (r164), while identical code in
ngx_recv.c introduced in the same import do actually set read->eof to 1.
Failure to set read->eof to 1 results in EOF not being generally detectable
from connection flags. On the other hand, kqueue won't report any read
events on such a connection since we use EV_CLEAR. This resulted in read
timeouts if such connection was cached and used for another request.
