This issue was introduced in libunit commit (e0f0cd7d244a). All port
sockets in application should be in blocking mode whereas Unit itself
operates non-blocking sockets.
Having non-blocking sockets in application may cause send error during
intensive response packets generation.
See https://mailman.nginx.org/pipermail/unit/2018-October/000080.html.
Currently we consider any changes with revision other than 1 as
packages-specific, thus there is no need to include such entries
to the generic Unit change log.
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.
Router reconfiguration may lead to starting new application processes, opening
listen ports etc. These actions are asynchronous and require message
exchange with master process. Router stores reference for controller
(response) port in structure associated with reconfiguration process (tmcf).
The port used to provide reconfiguration response (either success or failed)
to controller.
This commit increases response port use counter to make sure port structure
not freed while router waits for result of asynchronous operations.
Previously, passing 0 resulted in reading the whole body and all negative
values raised an exception.
Now the behaviour is in consistentance with io.RawIOBase.read() interface,
and passing 0 returns empty (byte) string, while -1 results in reading the
whole body.
Attribute 'application' is optional in listener object. This commit adds
missing code to reset 'lscf' to avoid garbage and crash when the attribute
is absent.
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.
For accurate app descriptor release, it is required to count the number of
use counts. Use count increased when:
- app linked to configuration app queue;
- socket conf stores pointer to app;
- request for start app process posted to router service thread;
Application port has pointer to app, but it does not increase use count
to avoid use count loop.
Timer needs a pointer to nxt_timer_t which is stored in engine timers tree.
nxt_timer_t now resides in nxt_app_joint_t and does not lock the application.
Start process port RPC handlers is also linked to nxt_app_joint_t.
App joint (nxt_app_joint_t) is a 'weak pointer':
- single threaded;
- use countable;
- store pointer to nxt_app_t (which can be NULL);
nxt_app_t has pointer to nxt_app_joint_t and update its pointer to app.
