This is required to avoid include cycles, as some nxt_clone_* functions
depend on the credential structures, but nxt_process depends on clone
structures.
- Introduced nxt_runtime_process_port_create().
- Moved nxt_process_use() into nxt_process.c from nxt_runtime.c.
- Renamed nxt_runtime_process_remove_pid() as nxt_runtime_process_remove().
- Some public functions transformed to static.
This closes#327 issue on GitHub.
When Unit starts, the main process waits for module discovery message for a
while. If a QUIT signal arrives at this time, the router and controller
processes created by main and Unit stay running. Also, the main process
doesn't stop them after the second QUIT signal is received in this case.
Router requests application start by sending port message with application
parameters to master. In response router gets application port. Stream id
used to link request and response. If application process terminates
unexpectedly (e.g. before ready state), it is required to notify router about
application start failure. For this purpose stream id is stored in process
initialization parameters.
Stream id sequentially incremented and starts from 1 in case of router
resurrection. New router application start stream id may coincide with
stream id of currently running/terminating application processes. In such
cases router may receive REMOVE_PID message with same stream id as used in
application start request and mistakenly reports application start failure.
This commit tries to avoid such errors by resetting stream for processes in
ready state.
Unit master process restarts the router if the router accidentally dies.
New router process receives the configuration from controller and starts
configured applications. The information of running applications cannot
be transferred to router because currently there is no persistent application
identifier. To avoid orphan application processes started by died router,
master process stops all currently running applications once it receives
SIGCHLD for router process.
The bug had appeared in 5cc5002a788e when process type has been
converted to bitmask. This commit reverts the type back to a number.
This commit is related to #131 issue on GitHub.
- Pre-fork 'processes.spare' application processes;
- fork more processes to keep 'processes.spare' idle processes;
- fork on-demand up to 'processes.max' count;
- scale down idle application processes above 'processes.spare' after
'processes.idle_timeout';
- number of concurrently started application processes also limited by
'processes.spare' (or 1, if spare is 0).
- Main process should be connected to all other processes.
- Controller should be connected to Router.
- Router should be connected to Controller and all Workers.
- Workers should be connected to Router worker thread ports only.
This filtering helps to avoid unnecessary communication and various errors
during massive application workers stop / restart.
- Each sendmsg() transmits no more than port->max_size payload data.
- Longer buffers are fragmented and send using multiple sendmsg() calls.
- On receive side, buffers are connected in chain.
- Number of handler calls is the same as number of nxt_port_socket_write()
calls.
- nxt_buf_make_plain() function introduced to make single plain buffer from
the chain.
Use counter helps to simplify logic around port and application free.
Port 'post' function introduced to simplify post execution of particular
function to original port engine's thread.
Write message queue is protected by mutex which makes port write operation
thread safe.
