After revisiting why this exists in Kore I decided it
does not belong in this platform and instead of letting
it sit there staring at me I rather just kill it.
Kore no longer passes the accept lock to the "next in line"
worker but instead all workers will attempt to grab the lock
if they can.
Also remember if we had the lock previous iteration of the
event loop and don't constantly disable/enable the accepting sockets.
Makes Kore scale even better across multiple cpu's.
Has support for full async pgsql queries. Most of the logic
is hidden behind a KORE_PGSQL() macro allowing you to insert
these pgsql calls in your page handlers without blocking the
kore worker while the query is going off.
There is place for improvement here, and perhaps KORE_PGSQL won't
stay as I feel this might overcomplicate things instead of making
them simpler as I thought it would.
If a worker reached worker_max_connections and it was its turn to
grab the accept lock it would've gotten stuck and no new connections
would be handled even if other workers would be less busy.
Instead, we now skip the lock if we're too busy and pass it along
in the hopes other workers are less busy.
This allows us to move the accept lock manually to another Kore worker
in case we own it and are about to do some heavy lifting on the current
Kore worker.
This is useful to track down any issues you might have in your module.
A log entry with a page handler causing issues looks like:
Jul 7 14:44:30 devbook kore[18191]: [parent]: worker 1 (18193)-> status 11
Jul 7 14:44:30 devbook kore[18191]: [parent]: worker 1 (pid: 18193) (hdlr: 0x242d9c0) gone
Jul 7 14:44:30 devbook kore[18191]: [parent]: hdlr serve_intro has caused 2 error(s)
- Introduce own memory management system on top of malloc to keep track
of all our allocations and free's. Later we should introduce a pooling
mechanism for fixed size allocations (http_request comes to mind).
- Introduce ssl_cipher in configuration.
Memory usage is kind of high right now, but it seems its OpenSSL
doing it rather then Kore.
- Introduce own memory management system on top of malloc to keep track
of all our allocations and free's. Later we should introduce a pooling
mechanism for fixed size allocations (http_request comes to mind).
- Introduce ssl_cipher in configuration.
Memory usage is kind of high right now, but it seems its OpenSSL
doing it rather then Kore.
Instead of waiting until one worker is filled up on connections
the workers find the next lowest loaded worker and will hand
over the lock to them instead. This will cause a nicer spread of load.
Instead of running one accept per event loop, we attempt to accept
as many as worker_max_connections allows.
Refactor net sending/recv code a bit.
new connections and which ones will not be notified for it.
Fixes the thundering herd problem, and nicely spreads out load between
all the workers equally. A configuration option (workers_max_connections)
is available to tweak how many connections a worker will have before
giving up the accept lock.
Two ways are added to this commit for access locking:
- Locking via semaphores.
- Locking via GCC's builtin atomic methods.
The default is running with semaphores disabled (OpenBSD cannot do
sem_init() with pshared set to 1, which is required).
If you want to use semaphores add KORE_USE_SEMAPHORES to CFLAGS,
and -lpthread to LDFLAGS in the Makefile.
Other fixes:
- BSD: add a timeout to kevent().
- Merge kore_worker_wait together, linux knows waitpid() as well.
- Send the correct SIGQUIT signal to workers instead of SIGINT.
- Fix kore_time_ms().
- Log fatal worker messages in syslog.
- Refactor code even more.
- Do not free our own kore_worker structure.
