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net/server_epoll.lua @ 11665:148075532021
net.server_epoll: Prevent stack overflow of opportunistic writes
net.http.files serving a big enough file on a fast enough connection
with opportunistic_writes enabled could trigger a stack overflow through
repeatedly serving more data that immediately gets sent, draining the
buffer and triggering more data to be sent. This also blocked the server
on a single task until completion or an error.
This change prevents nested opportunistic writes, which should prevent
the stack overflow, at the cost of reduced download speed, but this is
unlikely to be noticeable outside of Gbit networks. Speed at the cost of
blocking other processing is not worth it, especially with the risk of
stack overflow.
author | Kim Alvefur <zash@zash.se> |
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date | Sun, 11 Jul 2021 09:39:21 +0200 |
parent | 11660:68f0196ece2a |
child | 11671:4e4e26e3df8d |
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11664:d83f8f44caea | 11665:148075532021 |
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497 t_insert(buffer, data); | 497 t_insert(buffer, data); |
498 else | 498 else |
499 self.writebuffer = { data }; | 499 self.writebuffer = { data }; |
500 end | 500 end |
501 if not self._write_lock then | 501 if not self._write_lock then |
502 if cfg.opportunistic_writes then | 502 if cfg.opportunistic_writes and not self._opportunistic_write then |
503 self._opportunistic_write = true; | |
503 self:onwritable(); | 504 self:onwritable(); |
505 self._opportunistic_write = nil; | |
504 return #data; | 506 return #data; |
505 end | 507 end |
506 self:setwritetimeout(); | 508 self:setwritetimeout(); |
507 self:set(nil, true); | 509 self:set(nil, true); |
508 end | 510 end |