view docs/man/nginx.8 @ 8045: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 985b0bda403c
line wrap: on
line source

.\"
.\" Copyright (C) 2010, 2019 Sergey A. Osokin
.\" Copyright (C) Nginx, Inc.
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.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.