The application process needs to request the shared memory segment from the
router instead of the latter pushing the segment before sending a request to
the application. This is required to simplify the communication between the
router and the application and to prepare the router for using the application
shared port and then the queue.
The application process needs to request the port from the router instead of the
latter pushing the port before sending a request to the application. This is
required to simplify the communication between the router and the application
and to prepare the router to use the application shared port and then the queue.
If there are no listen sockets, the router configuration usage counter
remains 0 and never decreases. The only moment to release a configuration is
right after a configuration update.
A connection object is allocated in advance for each listen event object to be
used for the established connection. This connection needs to be freed when the
listen event is destroyed.
There is no restrictions on configration size and using segmented shared memory
only doubles memory usage because to parse configration on router side,
it needs to be 'plain' e. g. located in single continous memory buffer.
The lifespan of a listening socket is longer than both router
configuration's and temporary router configuration's lifespan,
so the sockets should be stored in persistent queues. Safety
is ensured by the fact that the router processes only one new
configuration at any time.
The process abstraction has changed to:
setup(task, process)
start(task, process_data)
prefork(task, process, mp)
The prefork() occurs in the main process right before fork.
The file src/nxt_main_process.c is completely free of process
specific logic.
The creation of a process now supports a PROCESS_CREATED state. The
The setup() function of each process can set its state to either
created or ready. If created, a MSG_PROCESS_CREATED is sent to main
process, where external setup can be done (required for rootfs under
container).
The core processes (discovery, controller and router) doesn't need
external setup, then they all proceeds to their start() function
straight away.
In the case of applications, the load of the module happens at the
process setup() time and The module's init() function has changed
to be the start() of the process.
The module API has changed to:
setup(task, process, conf)
start(task, data)
As a direct benefit of the PROCESS_CREATED message, the clone(2) of
processes using pid namespaces now doesn't need to create a pipe
to make the child block until parent setup uid/gid mappings nor it
needs to receive the child pid.
This is useful to escape "/" in path fragments. For example, in order
to reference the application named "foo/bar":
{
"pass": "applications/foo%2Fbar"
}
This is required due to lack of a graceful shutdown: there is a small gap
between the runtime's memory pool release and router process's exit. Thus, a
worker thread may start processing a request between these two operations,
which may result in an http fields hash access and subsequent crash.
To simplify issue reproduction, it makes sense to add a 2 sec sleep before
exit() in nxt_runtime_exit().
An earlier attempt (ad6265786871) to resolve this condition on the
router's side added a new issue: the app could get a request before
acquiring a port.
To avoid closing the body fd prematurely, the fd value is moved from
the request struct to the app link. The body fd should not be closed
immediately after the request is sent to the application due to possible
request rescheduling.
Router built with debug may stop with assertion during stalled requests
re-schedule. This was caused by missing reference counting increment
before nxt_router_port_select() call.
Re-scheduled req_app_link structures should have use_count exactly equal
to the number of references from the application and port list. However,
there's one extra usage decrement that occurs after the req_app_link is
created because the use_count is initialised as 1.
This patch removes all excess instances of the usage decrement that caused
preliminary req_app_link release and router process crash.
To reproduce the issue need to cause request rescheduling between 2 app
processes.
This issue was introduced in 61e9f23a566d.
- OOSM (out of shared memory). Sent by application process to router
when application reaches the limit of allocated shared memory and
needs more.
- SHM_ACK. Sent by router to application when the application's shared
memory is released and the OOSM flag is enabled for the segment.
This implements blocking mode (the library waits for SHM_ACK in case of
out of shared memory condition and retries allocating the required memory
amount) and non-blocking mode (the library notifies the application that
it's out of shared memory and returns control to the application module
that sets up the output queue and puts SHM_ACK in the main message loop).
The reason for the change is that the req_app_link reference count
was incorrect if the application crashed at start; in this case,
the nxt_request_app_link_update_peer() function was never called.
This closes#332 issue on GitHub.
The "nxt_http_websocket" request state, defined in "nxt_http_websocket.c",
is used in "nxt_router.c" and must be linked with external symbol declared
in "nxt_router.c".
Due to the missing "extern" keyword, building Unit with some linkers
(notably gold and LLD) caused WebSocket connections to get stuck or even
crash the router process.
Previously, the nxt_router_prepare_msg() function expected server host among
other headers unmodified. It's not true anymore since normalization of the
Host header has been introduced in 77aad2c142a0.
The nxt_unit_split_host() function was removed. It didn't work correctly with
IPv6 literals. Anyway, after 77aad2c142a0 the port splitting is done in router
while Host header processing.
It doesn't do anything useful, among creating a JSON message and logging it
to debug log. Besides that it causes segmentation fault if the RPC handler
is triggered with an empty buffer due to exiting of the main process.
Timers that don't require maximum precision (most of them, actually) can be
triggered earlier or later within the bias interval.
To reduce wakeups by timers, the expire function now triggers not only all
timers that fall within the elapsed time, but also those whose bias falls
within this interval.
