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by daper 1263 days ago
Varnish (HTTP caching only) also uses one thread per client. I believe worker threads are used to handle reuqests while a dedicated thread handles all the idle connections between requests using epoll(). Also per-threads stack size is lowered so thousands of threads don't occupy massive amount of memory.

Single threaded HTTP servers have their own issues. If the bottleneck is the storage then lack of async open()/stat() and some other calls is problematic. We feel that serving hundreds of millions of files (long tail content) from slow storage using nginx. For that reason you can configure nginx to spawn multiple processes.
2 comments
habibur 1263 days ago
Thought nginx epolls file i/o too along side socket i/o. Or did you find that the first call to open() or stat() stalls, while read/write after that continues normally?
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Matthias247 1262 days ago
File IO isn’t epoll-able. The operations are always blocking.

Those could however be offloaded onto a threadpool, to avoid the blocking to affect any other requests that are processed by the same Nginx worker. Nginx however only partially does that - whole file read and write operations are offloaded a whole bunch of other IO (stat, open, close) are executed on the main thread. I guess due to implementation challenges - one can’t just make one operation async but also needs to make each operation that utilizes those methods async.

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habibur 1262 days ago
Searched nginx source. Seems like it's using aio_read() aio_write()

./src/os/unix/ngx_file_aio_read.c

API's doc https://man7.org/linux/man-pages/man3/aio_read.3.html

Even though the source is there don't mean it's compiled or used though. Might or might not be. No idea about the details.

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rkeene2 1263 days ago
I wrote an extremely fast static HTTP server for this purpose [0].

[0] https://filed.rkeene.org/

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metadat 1263 days ago
Off-topic: What happened to rkeene1?

btw I really appreciate the design of you site, it's simple, clean, and beautiful. Timeless.

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bch 1262 days ago
It looks like @rkeene2 styled it, but that’s a site served up by fossil[0].

[0] https://www2.fossil-scm.org/home/doc/trunk/www/index.wiki

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