TIMEOUT

Timeout parameters in Squid can be based on overall connection timeouts, peer-specific timeouts, site/domain-specific timeouts, request-specific timeouts etc. Proper setting of timeout values is critical to optimal Squid performance. Relevant parameters for timeout settings are listed here.

forward_timeout	connect_timeout	peer_connect_timeout	read_timeout	request_timeout
persistent_request_timeout	client_lifetime	half_closed_clients	pconn_timeout	ident_timeout
shutdown_lifetime

TAG NAME	forward_timeout
Description	Specifies how long Squid should at most attempt in finding a forwarding path for the request before giving up.
Build Option	Default
Usage	forward_timeout time-units
Default	forward_timeout 4 minutes

Synopsis
This parameter specifies how long Squid should at most attempt in finding a forwarding path for the request before giving up.

Arguments

time-units

Connection timeout period

Example(s)
forward_timeout 4 minutes

TAG NAME	connect_timeout
Description	An option to force Squid to close connections after a specified time
Build Option	Default
Usage	connect_timeout time-units
Default	connect_timeout 2 minutes

Synopsis

Some systems (notably older Linux versions) can not be relied upon to time out connect requests. For this reason, this option specifies the timeout for how long Squid should wait for the connection to complete. This value defaults to 120 seconds (2 minutes).

Arguments

time-units

Connection timeout period

Example(s)
connect_timeout 180 seconds

TAG NAME	peer_connect_timeout
Description	This parameter specifies how long to wait for a pending TCP connection to a peer cache
Build Option	Default
Usage	peer_connect_timeout time-units
Default	peer_connect_timeout 30 seconds

Synopsis
default is 30 seconds. You may also set different timeout values for individual neighbors with the 'connect-timeout' option on a cache_peer line.

Note: Setting of peer_connect_timeout to more than 30 seconds will be a performance issue.

Arguments

time-units

Time to wait for pending TCP connection

Example(s)
peer_connect_timeout 45 seconds

TAG NAME	read_timeout
Description	Used to set the timeout period for server-side connections
Build Option	Default
Usage	read_timeout time-units
Default	read_timeout 15 minutes

Synopsis
On each successful read() request the timeout is reset to this amount. If no data is read within this period of time, the request is aborted and logged with ERR_READ_TIMEOUT.

Arguments

time-units

Reset time duration

Example(s)
read_timeout 10 minutes

TAG NAME	request_timeout
Description	Defines the timeout for HTTP requests from clients
Build Option	Default
Usage	request_timeout time-units
Default	request_timeout 5 minutes

Synopsis
Using this, instruct Squid to wait for an HTTP request after initial connection establishment. By default the value is 5 minutes.

Arguments

time-units

Wait time period after initial connection establishment

Example(s)
request_timeout 8 minutes

TAG NAME	persistent_request_timeout
Description	This defines the time period to wait for the next HTTP request on a persistent connection after the previous request completes
Build Option	Default
Usage	persistent_request_timeout time-units
Default	persistent_request_timeout 1 minute

Synopsis
This tag defines the time period between completion of a HTTP request and starting of the next request on persistent connection.

Arguments

time-units

Time duration between the requests

Example(s)
persistent_request_timeout 1 minute

TAG NAME	client_lifetime
Description	The time limit Squid sets for a client to remain connected to the cache process
Build Option	Default
Usage	client_lifetime time-units
Default	client_lifetime 1 day

Synopsis

This defines the maximum amount of time that a client (browser) is allowed to remain connected to the cache process. This is merely a safeguard against clients that disappear without properly shutting down. It is designed to prevent a large number of sockets from being tied up in a CLOSE_WAIT state. The default for this option is 1440 minutes, or 1 day.

Note
The default value is intended to be much larger than any client would ever need to be connected to your cache. You should probably change client_lifetime only as a last resort. If you seem to have many client connections tying up file descriptors, we recommend first tuning the read_timeout, request_timeout, pconn_timeout and quick_abort values. If the more file descriptors are in use then the memory in use will also increase, which is also a performance issue.

Arguments

time-units

Client lifetime with the cache

Example(s)
client_lifetime 1000 minutes

TAG NAME	half_closed_clients
Description	Defines Squid's behavior towards some types of clients that close the sending side of a connection while leaving the receiving side open
Build Option	Default
Usage	half_closed_clients on/off
Default	half_closed_clients on

Synopsis
Turning this option off will cause Squid to immediately close connections when a read(2) returns "no more data to read". It's usually safe to leave this at the default value of on.

Arguments

on/off

Enable or disable this action

Example(s)
half_closed_clients off

TAG NAME	pconn_timeout
Description	Defines the timeout value for persistent connections
Build Option	Default
Usage	pconn_timeout time-units
Default	pconn_timeout 120 seconds

Synopsis

When this timeout is set, Squid will close persistent connections if they are idle for this amount of time. Persistent connections will be disabled entirely if this option is set to a value less than 10 seconds. The default is 120 seconds.

Arguments

time-units

Time period to wait for closing idle connections

Example(s)
pconn_timeout 2 minutes

TAG NAME	ident_timeout
Description	Maximum time to wait for IDENT lookups to complete
Build Option	Default
Usage	ident_timeout time-units
Default	ident_timeout 10 seconds

Synopsis
The timeout, usually in seconds. If this is set too high, you may be susceptible to denial or service from having too many outstanding ident requests. The default for this is 10 seconds.

Arguments

time-units

Time duration to wait during ident lookups

Example(s)
ident_timeout 5 seconds

TAG NAME	shutdown_lifetime
Description	This is the time Squid allows for existing connections to continue after it has received a shutdown signal
Build Option	Default
Usage	shutdown_lifetime time-units
Default	shutdown_lifetime 30 seconds

Synopsis

When SIGTERM or SIGHUP is received, the cache is put into "shutdown pending" mode until all active sockets are closed. It will stop accepting new connections immediately, but connections already in progress will continue to be served for this amount of time. Defaults to 30 seconds, which is a good safe value. Any active clients after this many seconds will receive a "timeout" message.

Note
If this time is set to be too low then some file descriptors may remain open which will be a performance issue in memory usage.

Arguments

time-units

Time period of "shutdown pending" mode

Example(s)
shutdown_lifetime 20 seconds