- Change pools to use mmap() for allocating regions.
- Change kore_malloc() to use pools for commonly sized objects.
(split into multiple of 2 buckets, starting at 8 bytes up to 8192).
- Rename kore_mem_free() to kore_free().
The preallocated pools will hold up to 128K of elements per block size.
In case a larger object is to be allocated kore_malloc() will use
malloc() instead.
Setting the handle callback allows your application
to take care of network events for the connection.
Look at the connection state and flags to determine
if read/write is possible and go from there.
See kore_connection_handle() for more details.
With this framework apps can now send messages between worker processes.
A new API function exists:
int kore_msg_register(u_int8_t id, void (*cb)(const void *, u_int32_t);
This API call allows your app to register a new message callback for a given ID.
You can then send messages on this ID to other workers using:
void kore_msg_send(u_int8_t id, void *data, u_int32_t length);
This framework will interally be used for a few things such as allowing
websocket data to broadcasted between all workers, adding unified caching
and hopefully eventually moving the access log to this as well.
Some internals have changed with this commit:
* worker_clients has been called connections.
* the parent now initializes the net, and event subsystems.
* kore_worker_websocket_broadcast() is dead.
This configuration option limits the maximum number
of connections a worker process can accept() in a single
event loop.
It can be used to more evenly spread out incoming connections
across workers when new connections arrive in a burst.
In cases where accept() failed Kore would not relinquish the
lock towards other worker processes.
This becomes evident when dealing with a high number of concurrent
connections to the point the fd table gets full. In this scenario
the worker with the full fd table will spin on attempt to accept
newer connections.
As a bonus, Kore now has allows exactly up to worker_max_connections
of connections per worker before no longer attempting to grab the
accept lock.
Introduces two new configuration knobs:
* socket_backlog (backlog for listen(2))
* http_request_limit
The second one is the most interesting one.
Before, kore would iterate over all received HTTP requests
in its queue before returning out of http_process().
Under heavy load this queue can cause Kore to spend a considerable
amount of time iterating over said queue. With the http_request_limit,
kore will process at MOST http_request_limit requests before returning
back to the event loop.
This means responses to processed requests are sent out much quicker
and allows kore to handle any other incoming requests more gracefully.
- The net code no longer has a recv_queue, instead reuse same recv buffer.
- Introduce net_recv_reset() to reset the recv buffer when needed.
- Have the workers spread the load better between them by slightly
delaying their next accept lock and giving them an accept treshold
so they don't go ahead and keep accepting connections if they end
up winning the race constantly between the workers.
- The kore_worker_acceptlock_release() is no longer available.
- Prepopulate the HTTP server response header that is added to each
response in both normal HTTP and SPDY modes.
- The path and host members of http_request are now allocated on the heap.
These changes overall result better performance on a multicore machine,
especially the worker load changes shine through.
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.
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.
Joris Vink
Stig Telfer