Mercurial > hg > nginx-quic
view docs/man/nginx.8 @ 8896:aa28c802409f
Resolver: make TCP write timer event cancelable.
Similar to 70e65bf8dfd7, the change is made to ensure that the ability to
cancel resolver tasks is fully controlled by the caller. As mentioned in the
referenced commit, it is safe to make this timer cancelable because resolve
tasks can have their own timeouts that are not cancelable.
The scenario where this may become a problem is a periodic background resolve
task (not tied to a specific request or a client connection), which receives a
response with short TTL, large enough to warrant fallback to a TCP query.
With each event loop wakeup, we either have a previously set write timer
instance or schedule a new one. The non-cancelable write timer can delay or
block graceful shutdown of a worker even if the ngx_resolver_ctx_t->cancelable
flag is set by the API user, and there are no other tasks or connections.
We use the resolver API in this way to maintain the list of upstream server
addresses specified with the 'resolve' parameter, and there could be third-party
modules implementing similar logic.
author | Aleksei Bavshin <a.bavshin@f5.com> |
---|---|
date | Wed, 01 Jun 2022 20:17:23 -0700 |
parents | f57a478aa16d |
children |
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.\" .\" Copyright (C) 2010, 2019 Sergey A. Osokin .\" Copyright (C) Nginx, Inc. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" .Dd November 5, 2020 .Dt NGINX 8 .Os .Sh NAME .Nm nginx .Nd "HTTP and reverse proxy server, mail proxy server" .Sh SYNOPSIS .Nm .Op Fl ?hqTtVv .Op Fl c Ar file .Op Fl e Ar file .Op Fl g Ar directives .Op Fl p Ar prefix .Op Fl s Ar signal .Sh DESCRIPTION .Nm (pronounced .Dq engine x ) is an HTTP and reverse proxy server, a mail proxy server, and a generic TCP/UDP proxy server. It is known for its high performance, stability, rich feature set, simple configuration, and low resource consumption. .Pp The options are as follows: .Bl -tag -width ".Fl d Ar directives" .It Fl ?\& , h Print help. .It Fl c Ar file Use an alternative configuration .Ar file . .It Fl e Ar file Use an alternative error log .Ar file . Special value .Cm stderr indicates that the standard error output should be used. .It Fl g Ar directives Set global configuration directives. See .Sx EXAMPLES for details. .It Fl p Ar prefix Set the prefix path. The default value is .Pa %%PREFIX%% . .It Fl q Suppress non-error messages during configuration testing. .It Fl s Ar signal Send a signal to the master process. The argument .Ar signal can be one of: .Cm stop , quit , reopen , reload . The following table shows the corresponding system signals: .Pp .Bl -tag -width ".Cm reopen" -compact .It Cm stop .Dv SIGTERM .It Cm quit .Dv SIGQUIT .It Cm reopen .Dv SIGUSR1 .It Cm reload .Dv SIGHUP .El .It Fl T Same as .Fl t , but additionally dump configuration files to standard output. .It Fl t Do not run, just test the configuration file. .Nm checks the configuration file syntax and then tries to open files referenced in the configuration file. .It Fl V Print the .Nm version, compiler version, and .Pa configure script parameters. .It Fl v Print the .Nm version. .El .Sh SIGNALS The master process of .Nm can handle the following signals: .Pp .Bl -tag -width ".Dv SIGINT , SIGTERM" -compact .It Dv SIGINT , SIGTERM Shut down quickly. .It Dv SIGHUP Reload configuration, start the new worker process with a new configuration, and gracefully shut down old worker processes. .It Dv SIGQUIT Shut down gracefully. .It Dv SIGUSR1 Reopen log files. .It Dv SIGUSR2 Upgrade the .Nm executable on the fly. .It Dv SIGWINCH Shut down worker processes gracefully. .El .Pp While there is no need to explicitly control worker processes normally, they support some signals too: .Pp .Bl -tag -width ".Dv SIGINT , SIGTERM" -compact .It Dv SIGTERM Shut down quickly. .It Dv SIGQUIT Shut down gracefully. .It Dv SIGUSR1 Reopen log files. .El .Sh DEBUGGING LOG To enable a debugging log, reconfigure .Nm to build with debugging: .Pp .Dl "./configure --with-debug ..." .Pp and then set the .Cm debug level of the .Va error_log : .Pp .Dl "error_log /path/to/log debug;" .Pp It is also possible to enable the debugging for a particular IP address: .Bd -literal -offset indent events { debug_connection 127.0.0.1; } .Ed .Sh ENVIRONMENT The .Ev NGINX environment variable is used internally by .Nm and should not be set directly by the user. .Sh FILES .Bl -tag -width indent .It Pa %%PID_PATH%% Contains the process ID of .Nm . The contents of this file are not sensitive, so it can be world-readable. .It Pa %%CONF_PATH%% The main configuration file. .It Pa %%ERROR_LOG_PATH%% Error log file. .El .Sh EXIT STATUS Exit status is 0 on success, or 1 if the command fails. .Sh EXAMPLES Test configuration file .Pa ~/mynginx.conf with global directives for PID and quantity of worker processes: .Bd -literal -offset indent nginx -t -c ~/mynginx.conf \e -g "pid /var/run/mynginx.pid; worker_processes 2;" .Ed .Sh SEE ALSO .\"Xr nginx.conf 5 .\"Pp Documentation at .Pa http://nginx.org/en/docs/ . .Pp For questions and technical support, please refer to .Pa http://nginx.org/en/support.html . .Sh HISTORY Development of .Nm started in 2002, with the first public release on October 4, 2004. .Sh AUTHORS .An -nosplit .An Igor Sysoev Aq Mt igor@sysoev.ru . .Pp This manual page was originally written by .An Sergey A. Osokin Aq Mt osa@FreeBSD.org.ru as a result of compiling many .Nm documents from all over the world.