timeout

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

max_filedescriptors

accept_filter

incoming_rate

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

Example(s)
forward_timeout 4 minutes

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

Example(s)
connect_timeout 180 seconds

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

Example(s)
peer_connect_timeout 45 seconds

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

Example(s)
read_timeout 10 minutes

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

Example(s)
request_timeout 8 minutes

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

Example(s)
persistent_request_timeout 1 minute

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

Example(s)
client_lifetime 1000 minutes

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

Example(s)
half_closed_clients off

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

Example(s)
pconn_timeout 2 minutes

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

Example(s)
ident_timeout 5 seconds

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

Example(s)
shutdown_lifetime 20 seconds

Description

This option is used to define the number of file descriptors for squid.

Build Option

--with-maxfd

Usage

max_filedescriptors Number-Of-Filedescriptor

Default

max_filedescriptors 0

Synopsis

The maximum number of file descriptors assigned for squid. The default "0" means Squid inherits the current ulimit setting.

Note
Restart of Squid is required on enabling this feature. Also not all comm loops supports values larger than --with-maxfd.

Example(s)
max_filedescriptors 32768

Description

Specifies the name of the accept filter to install on squid's listen socket.

Build Option

Default

Usage

accept_filter httpready | data

Default

none

Synopsis

The name of an accept filter to install on Squid's listen socket(s).

Options for BSD
This feature is specific to FreeBSD and requires support in the kernel.
1.httpready
This filter delays the delivery of new connections to squid until a full http requests has been received.
2.dataready
This filter delays the delevery of new connections until afull HTTP request has been received.

Options for Linux
data
This filter delays the delivery of new connections to squid until is some data to process by TCP_ACCEPT_DEFER.

Example(s)
FreeBSD
accept_filter httpready
Linux
accept_filter data

Description

Controls squid how aggressive the new connections are accepted when compared to processing existing connections.

Build Option

Default

Usage

incoming_rate value

Default

incoming_rate 30

Synopsis

This option controls how aggressive Squid should accept new connections compared to processing existing connections.

Example(s)
incoming_rate 60